JSON Class

Properties Methods Events Config Settings Errors

The JSON class can be used to parse and write JSON documents.

Syntax

JSON

Remarks

The JSON class offers a fast and simple way to parse and write information in JSON documents.

Parsing JSON

The JSON class parses JSON documents and verifies that they are well-formed. The results are provided through a set of events.

In addition, the document structure may be queried through an XPath mechanism that supports a subset of the XPath and JSONPath specification.

The parser is optimized for read applications, with a very fast engine that builds internal DOM structures with close to zero heap allocations. Additionally, BuildDOM can be set to False, which reduces the overhead of creating the DOM and offers a fast forward-only parsing implementation that fires events to provide the parsed data.

When parsing a document, events will fire to provide information about the parsed data. After Parse returns the document, it may be navigated by setting XPath if BuildDOM is True (default). If BuildDOM is False, parsed data are accessible only through the events.

The following events will fire during parsing:

StartElement
Characters
EndElement
IgnorableWhitespace

If BuildDOM is True (default), XPath may be set after this method returns. XPath may be set to navigate to specific elements within the JSON document. This will be the path to a specified value within the document. Because arrays in JSON only contain values, and no associated object name, an empty name will be used for these values. To reach an array element at position 1, the path must be set to "[1]". In addition, a root element named "json" will be added to each JSON document in the parser.

BuildDOM must be set to True before parsing the document for the XPath functionality to be available.

The XPath property accepts both XPath and JSONPath formats. Please review the following notes on both formats.

XPath

The path is a series of one or more element accessors separated by '/'. The path can be absolute (starting with '/') or relative to the current XPath location.

The following are possible values for an element accessor:


'name'	A particular element name.
[i]	The i-th subelement of the current element.
..	the parent of the current element.

When XPath is set to a valid path, the following properties are updated:

XElement
XElementType
XParent
XText
XSubTree
XChildren*

BuildDOM must be set to True before parsing the document for the XPath functionality to be available.

Simple JSON Document

{
  "firstlevel": {
    "one": "value",
    "two": ["first", "second"],
    "three": "value three"
  }
}

Example 1. Setting XPath:


Document root	JsonControl.XPath = "/"
Specific Element	JsonControl.XPath = "/json/firstlevel/one/"
i-th Child	JsonControl.XPath = "/json/firstlevel/two/[i]/"

Note: When using XPath notation, the root element is always referred to as "json". As in the previous examples, this means all paths will begin with "/json".

JSONPath

This property implements a subset of the JSONPath notation. This may be set to point to a specific element in the JSON document.

The JSONPath is a series of one or more accessors in either dot-notation

$.store.book[0].title

or in bracket-notation, as follows:

$['store']['book'][0]['title']

After setting XPath, the following properties are populated:

XChildren
XElement
XElementType
XSubTree
XText

Example 2. Setting JSONPath:

Given the following JSON document:

{
    "store": {
        "book": [
            {
                "category": "reference",
                "author": "Nigel Rees",
                "title": "Sayings of the Century",
                "price": 8.95
            },
            {
                "category": "fiction",
                "author": "Evelyn Waugh",
                "title": "Sword of Honour",
                "price": 12.99
            },
            {
                "category": "fiction",
                "author": "Herman Melville",
                "title": "Moby Dick",
                "isbn": "0-553-21311-3",
                "price": 8.99
            },
            {
                "category": "fiction",
                "author": "J. R. R. Tolkien",
                "title": "The Lord of the Rings",
                "isbn": "0-395-19395-8",
                "price": 22.99
            }
        ],
        "bicycle": {
            "color": "red",
            "price": 19.95
        }
    },
}

The following code shows several examples.

Get the first book's author:

json.XPath = "$.store.book[0].author"; Console.WriteLine(json.XText); //Output //"Nigel Rees" Select the first book and inspect the children:

json.XPath = "$.store.book[0]"; Console.WriteLine("Child Count: " + json.XChildren.Count); Console.WriteLine(json.XChildren[1].Name + ": " + json.XChildren[1].XText); //Output //Child Count: 4 //author: "Nigel Rees" Get the price of the second book:

json.XPath = "$['store']['book'][1]['price']"; Console.WriteLine(json.XText); //Output //12.99 Get the second to last book's author:

json.XPath = "$['store']['book'][last() - 1]['author']"; Console.WriteLine(json.XText); Console.WriteLine(json.XPath); //Note that "last() - 1" is resolved to "3". //Output //"Herman Melville" //$['store']['book'][3]['author'] Display the full subtree at the current path:

json.XPath = "$.store.book[0]"; Console.WriteLine(json.XSubTree); //Output // { // "category": "reference", // "author": "Nigel Rees", // "title": "Sayings of the Century", // "price": 8.95 // }

Input Properties

The class will determine the source of the input based on which properties are set.

The order in which the input properties are checked is as follows:

InputFile
InputData

When a valid source is found, the search stops.

If parsing multiple documents, call Reset between documents to reset the parser.

Writing JSON

The JSON class also can be used to create a JSON document.

The document is written to the selected output property. In addition, as the document is written, the JSON event will fire. The Text event parameter contains the part of the document currently being written.

Output Properties

The class will determine the destination of the output based on which properties are set.

The order in which the output properties are checked is as follows:

OutputFile
OutputData: The output data are written to this property if no other destination is specified.

Example. Writing a JSON Document:

Writing a simple JSON document describing a pet: Json json = new Json(); json.OutputFile = "C:\\temp\\fido.json"; json.StartObject(); json.PutProperty("name", "fido", 2); json.PutName("previousOwners"); json.StartArray(); json.PutValue("Steve Widgetson", 2); json.PutValue("Wanda Widgetson", 2); json.PutValue("Randy Cooper", 2); json.PutValue("Linda Glover", 2); json.EndArray(); json.PutProperty("weightUnit", "lbs", 2); json.PutProperty("weight", "62", 3); json.EndObject(); json.Flush();

This example results in the following JSON:

{
  "name": "fido",
  "previousOwners": [
    "Steve Widgetson",
    "Wanda Widgetson",
    "Randy Cooper",
    "Linda Glover"
  ],
  "weightUnit": "lbs",
  "weight": 62
}

When writing multiple documents, call Reset between documents to reset the writer.

Modifying JSON

The JSON class also allows for modifying existing JSON documents. After loading a JSON document with Parse the document may be edited. The class supports inserting new values, renaming or overwriting existing values, and removing values. After editing is complete, call Save to output the updated JSON document.

The following methods are applicable when modifying a JSON document:

InsertProperty
InsertValue
Remove
Save
SetName
SetValue

When Save is called, the modified JSON is written to the specified output location.

Output Properties

The class will determine the destination of the output based on which properties are set.

The order in which the output properties are checked is as follows:

OutputFile
OutputData: The output data are written to this property if no other destination is specified.

Example 1. Inserting New Values:

To insert new values in a JSON document, first load the existing document with Parse. Next set XPath to the sibling or parent of the data to be inserted. Call InsertProperty or InsertValue and pass the ValueType and Position parameters to indicate the type of data being inserted and the position.

The ValueType parameter of these methods specifies the type of the value. Possible values are as follows:

0 (Object)
1 (Array)
2 (String)
3 (Number)
4 (Bool)
5 (Null)
6 (Raw)

The Position parameter of these methods specifies the position of Value. Possible values are as follows:

0 (Before the current element)
1 (After the current element)
2 (The first child of the current element)
3 (The last child of the current element)

For example:

Given the following JSON:

{
    "store": {
        "books": [
            {
                "category": "reference",
                "author": "Nigel Rees",
                "title": "Sayings of the Century",
            },
            {
                "category": "fiction",
                "author": "Evelyn Waugh",
                "title": "Sword of Honour",
            }
        ]    
    }
}

Insert a new property "price" for each book:

json.XPath = "/json/store/books/[1]"; json.InsertProperty("price", "8.95", 3, 3); //3 - Number, 3 - Last Child json.XPath = "/json/store/books/[2]"; json.InsertProperty("price", "12.99", 3, 3); //3 - Number, 3 - Last Child json.Save();

Produces the JSON:

{
  "store": {
    "books": [
    {
      "category": "reference",
      "author": "Nigel Rees",
      "title": "Sayings of the Century",
      "price": 8.95
    },
    {
      "category": "fiction",
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 12.99
    }
    ]
  }
}

To add a new book to the array:

json.XPath = "/json/store/books"; json.InsertValue("", 0, 3); //0 - Object, 3 - Last Child json.XPath = "/json/store/books/[3]"; json.InsertProperty("category", "fiction", 2, 3); //2 - String, 3 - Last Child json.InsertProperty("author", "Herman Melville", 2, 3); //2 - String, 3 - Last Child json.InsertProperty("title", "Moby Dick", 2, 3); //2 - String, 3 - Last Child json.InsertProperty("price", "8.99", 3, 3); //3 - Number, 3 - Last Child json.Save();

Produces the JSON:

{
  "store": {
    "books": [
    {
      "category": "reference",
      "author": "Nigel Rees",
      "title": "Sayings of the Century",
      "price": 8.95
    },
    {
      "category": "fiction",
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 12.99
    },
    {
      "category": "fiction",
      "author": "Herman Melville",
      "title": "Moby Dick",
      "price": 8.99
    }
    ]
  }
}

To add a new array property to each book:

json.XPath = "/json/store/books/[1]"; json.InsertProperty("tags", "", 1, 2); //1 - Array, 2 - First Child json.XPath = "/json/store/books/[1]/tags"; json.InsertValue("quotes", 2, 3); //2 - String, 3 - Last Child json.InsertValue("british", 2, 3); //2 - String, 3 - Last Child json.XPath = "/json/store/books/[2]"; json.InsertProperty("tags", "", 1, 2); //1 - Array, 2 - First Child json.XPath = "/json/store/books/[2]/tags"; json.InsertValue("trilogy", 2, 3); //2 - String, 3 - Last Child json.InsertValue("war", 2, 3); //2 - String, 3 - Last Child json.XPath = "/json/store/books/[3]"; json.InsertProperty("tags", "", 1, 2); //1 - Array, 2 - First Child json.XPath = "/json/store/books/[3]/tags"; json.InsertValue("classic", 2, 3); //2 - String, 3 - Last Child json.InsertValue("whales", 2, 3); //2 - String, 3 - Last Child json.Save();

Produces the JSON:

{
  "store": {
    "books": [
    {
      "tags": ["quotes", "british"],
      "category": "reference",
      "author": "Nigel Rees",
      "title": "Sayings of the Century",
      "price": 8.95
    },
    {
      "tags": ["trilogy", "war"],
      "category": "fiction",
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 12.99
    },
    {
      "tags": ["classic", "whales"],
      "category": "fiction",
      "author": "Herman Melville",
      "title": "Moby Dick",
      "price": 8.99
    }
    ]
  }
}

Example 2. Removing Values:

To remove existing values, set XPath and call the Remove method. Continuing with example 1, to remove the first book: json.XPath = "/json/store/books/[1]"; json.Remove(); json.Save();

Produces the JSON:

{
  "store": {
    "books": [
    {
      "tags": ["trilogy", "war"],
      "category": "fiction",
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 12.99
    },
    {
      "tags": ["classic", "whales"],
      "category": "fiction",
      "author": "Herman Melville",
      "title": "Moby Dick",
      "price": 8.99
    }
    ]
  }
}

To remove the "category" properties from each book: json.XPath = "/json/store/books/[1]/category"; json.Remove(); json.XPath = "/json/store/books/[2]/category"; json.Remove(); json.Save();

Produces the JSON:

{
  "store": {
    "books": [
    {
      "tags": ["trilogy", "war"],
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 12.99
    },
    {
      "tags": ["classic", "whales"],
      "author": "Herman Melville",
      "title": "Moby Dick",
      "price": 8.99
    }
    ]
  }
}

Example 3. Updating Existing Names and Values:

The SetName and SetValue methods may be used to modify existing names and values. Continuing with the preceding JSON in example 2, to rename "tags" to "meta" and update values within the array and prices:

//Rename "tags" to "meta" for 1st book json.XPath = "/json/store/books/[1]/tags"; json.SetName("meta"); //Update Price json.XPath = "/json/store/books/[1]/price"; json.SetValue("13.99", 3); //3 - Number //Rename "tags" to "meta" for 2nd book json.XPath = "/json/store/books/[2]/tags"; json.SetName("meta"); //Update tag "whales" to "revenge" json.XPath = "/json/store/books/[2]/meta/[2]"; json.SetValue("revenge", 2); //2 - String //Update Price json.XPath = "/json/store/books/[2]/price"; json.SetValue("9.99", 3); //3 - Number json.Save();

Produces the JSON:

{
  "store": {
    "books": [
    {
      "meta": ["trilogy", "war"],
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 13.99
    },
    {
      "meta": ["classic", "revenge"],
      "author": "Herman Melville",
      "title": "Moby Dick",
      "price": 9.99
    }
    ]
  }
}

Property List

The following is the full list of the properties of the class with short descriptions. Click on the links for further details.


BuildDOM	When True, an internal object model of the JSON document is created.
InputData	This property includes the JSON data to parse.
InputFile	The file to process.
OutputData	This property includes the output JSON after processing.
OutputFile	This is the path to a local file where the output will be written.
Overwrite	This property indicates whether or not the class should overwrite files.
Validate	This property controls whether documents are validated during parsing.
XChildCount	The number of records in the XChild arrays.
XChildElementType	The ElementType property indicates the data type of the element.
XChildName	The Name property provides the name of the element.
XChildXText	This property contains the text of the element.
XElement	This property includes the name of the current element.
XElementType	This property indicates the data type of the current element.
XErrorPath	This property includes an XPath to check the server response for errors.
XParent	The parent of the current element.
XPath	This property provides a way to point to a specific element in the response.
XSubTree	This property includes a snapshot of the current element in the document.
XText	This property includes the text of the current element.

Method List

The following is the full list of the methods of the class with short descriptions. Click on the links for further details.


Config	Sets or retrieves a configuration setting.
EndArray	This method writes the closing bracket of a JSON array.
EndObject	This method writes the closing brace of a JSON object.
Flush	This method flushes the parser's or writer's buffers.
HasXPath	Determines whether a specific element exists in the document.
InsertProperty	This method inserts the specified name and value at the selected position.
InsertValue	This method inserts the specified value at the selected position.
Parse	This method parses the specified JSON data.
PutName	This method writes the name of a property.
PutProperty	This method writes a property and value.
PutRaw	This method writes a raw JSON fragment.
PutValue	This method writes a value of a property.
Remove	This method removes the element or value set in XPath.
Reset	This method resets the class.
Save	This method saves the modified JSON document.
SetInputStream	Sets the stream from which the class will read data to parse.
SetName	This method sets a new name for the element specified by XPath.
SetOutputStream	This method sets the stream to which the class will write the JSON.
SetValue	This method sets a new value for the element specified by XPath.
StartArray	This method writes the opening bracket of a JSON array.
StartObject	This event writes the opening brace of a JSON object.
TryXPath	Navigates to the specified XPath if it exists.

Event List

The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.


Characters	This event is fired for plaintext segments of the input stream.
EndDocument	This event fires when the end of a JSON document is encountered.
EndElement	This event is fired when an end-element tag is encountered.
Error	Fired when information is available about errors during data delivery.
IgnorableWhitespace	This event is fired when a section of ignorable whitespace is encountered.
JSON	This event fires with the JSON data being written.
StartDocument	This event fires when the start of a new JSON document is encountered.
StartElement	This event is fired when a new element is encountered in the document.

Config Settings

The following is a list of config settings for the class with short descriptions. Click on the links for further details.


CacheContent	If true, the original JSON is stored internally in a buffer.
CloseInputStreamAfterProcess	Determines whether or not the input stream is closed after processing.
CloseOutputStreamAfterProcess	Determines whether or not the output stream is closed after processing.
ElementXPath	The XPath value for the current element in the document.
EscapeForwardSlashes	Whether to escape forward slashes when writing a JSON object.
InputFormat	Specifies the input format used in JSON streaming.
PrettyPrint	Determines whether output is on one line or "pretty printed".
RecordEndDelimiter	The character sequence after the end of a JSON document.
RecordStartDelimiter	The character sequence before the start of a JSON document.
StringProcessingOptions	Defines options to use when processing string values.
XPathNotation	Specifies the expected format when setting XPath.

BuildDOM Property (JSON Class)

When True, an internal object model of the JSON document is created.

Syntax

ANSI (Cross Platform)
int GetBuildDOM();
int SetBuildDOM(int bBuildDOM);

Unicode (Windows)
BOOL GetBuildDOM();
INT SetBuildDOM(BOOL bBuildDOM);

int ipworksmq_json_getbuilddom(void* lpObj);
int ipworksmq_json_setbuilddom(void* lpObj, int bBuildDOM);

bool GetBuildDOM();
int SetBuildDOM(bool bBuildDOM);

Default Value

TRUE

Remarks

Set this property to True when you need to browse the current document through XPath.

Data Type

Boolean

InputData Property (JSON Class)

This property includes the JSON data to parse.

Syntax

ANSI (Cross Platform)
char* GetInputData();
int SetInputData(const char* lpszInputData);

Unicode (Windows)
LPWSTR GetInputData();
INT SetInputData(LPCWSTR lpszInputData);

char* ipworksmq_json_getinputdata(void* lpObj);
int ipworksmq_json_setinputdata(void* lpObj, const char* lpszInputData);

QString GetInputData();
int SetInputData(QString qsInputData);

Default Value

Remarks

This property specifies the JSON to be processed. Set this property before calling Parse.

This may be set to a complete JSON document, or partial data. When setting partial data, call Parse after each chunk of data is set. For instance:

//Parse the following in chunks: { "data": 1} json.InputData = "{ \"data\"" json.Parse(); json.InputData = ": 1}" json.Parse();

Input Properties

The class will determine the source of the input based on which properties are set.

The order in which the input properties are checked is as follows:

InputFile
InputData

When a valid source is found, the search stops.

Data Type

String

InputFile Property (JSON Class)

The file to process.

Syntax

ANSI (Cross Platform)
char* GetInputFile();
int SetInputFile(const char* lpszInputFile);

Unicode (Windows)
LPWSTR GetInputFile();
INT SetInputFile(LPCWSTR lpszInputFile);

char* ipworksmq_json_getinputfile(void* lpObj);
int ipworksmq_json_setinputfile(void* lpObj, const char* lpszInputFile);

QString GetInputFile();
int SetInputFile(QString qsInputFile);

Default Value

Remarks

This property specifies the file to be processed. Set this property to the full or relative path to the file which will be processed.

After setting this property call Parse to parse the document.

Input Properties

The class will determine the source of the input based on which properties are set.

The order in which the input properties are checked is as follows:

InputFile
InputData

When a valid source is found, the search stops.

Data Type

String

OutputData Property (JSON Class)

This property includes the output JSON after processing.

Syntax

ANSI (Cross Platform)
char* GetOutputData();
int SetOutputData(const char* lpszOutputData);

Unicode (Windows)
LPWSTR GetOutputData();
INT SetOutputData(LPCWSTR lpszOutputData);

char* ipworksmq_json_getoutputdata(void* lpObj);
int ipworksmq_json_setoutputdata(void* lpObj, const char* lpszOutputData);

QString GetOutputData();
int SetOutputData(QString qsOutputData);

Default Value

Remarks

This property contains the resultant JSON after processing.

Output Properties

The class will determine the destination of the output based on which properties are set.

The order in which the output properties are checked is as follows:

OutputFile
OutputData: The output data are written to this property if no other destination is specified.

Data Type

String

OutputFile Property (JSON Class)

This is the path to a local file where the output will be written.

Syntax

ANSI (Cross Platform)
char* GetOutputFile();
int SetOutputFile(const char* lpszOutputFile);

Unicode (Windows)
LPWSTR GetOutputFile();
INT SetOutputFile(LPCWSTR lpszOutputFile);

char* ipworksmq_json_getoutputfile(void* lpObj);
int ipworksmq_json_setoutputfile(void* lpObj, const char* lpszOutputFile);

QString GetOutputFile();
int SetOutputFile(QString qsOutputFile);

Default Value

Remarks

This property specifies the file to which the output will be written. This may be set to an absolute or relative path.

Output Properties

The class will determine the destination of the output based on which properties are set.

The order in which the output properties are checked is as follows:

OutputFile
OutputData: The output data are written to this property if no other destination is specified.

Data Type

String

Overwrite Property (JSON Class)

This property indicates whether or not the class should overwrite files.

Syntax

ANSI (Cross Platform)
int GetOverwrite();
int SetOverwrite(int bOverwrite);

Unicode (Windows)
BOOL GetOverwrite();
INT SetOverwrite(BOOL bOverwrite);

int ipworksmq_json_getoverwrite(void* lpObj);
int ipworksmq_json_setoverwrite(void* lpObj, int bOverwrite);

bool GetOverwrite();
int SetOverwrite(bool bOverwrite);

Default Value

FALSE

Remarks

This property indicates whether or not the class will overwrite OutputFile. If Overwrite is False, an error will be thrown whenever OutputFile exists before an operation. The default value is False.

Data Type

Boolean

Validate Property (JSON Class)

This property controls whether documents are validated during parsing.

Syntax

ANSI (Cross Platform)
int GetValidate();
int SetValidate(int bValidate);

Unicode (Windows)
BOOL GetValidate();
INT SetValidate(BOOL bValidate);

int ipworksmq_json_getvalidate(void* lpObj);
int ipworksmq_json_setvalidate(void* lpObj, int bValidate);

bool GetValidate();
int SetValidate(bool bValidate);

Default Value

TRUE

Remarks

When true (default) the document will be validated during parsing. To disable validation set Validate to false. Disabling validation may be useful in cases where data can still be parsed even if the document is not well-formed.

Data Type

Boolean

XChildCount Property (JSON Class)

The number of records in the XChild arrays.

Syntax

ANSI (Cross Platform)
int GetXChildCount();
int SetXChildCount(int iXChildCount);

Unicode (Windows)
INT GetXChildCount();
INT SetXChildCount(INT iXChildCount);

int ipworksmq_json_getxchildcount(void* lpObj);
int ipworksmq_json_setxchildcount(void* lpObj, int iXChildCount);

int GetXChildCount();
int SetXChildCount(int iXChildCount);

Default Value

Remarks

This property controls the size of the following arrays:

XChildElementType
XChildName
XChildXText

The array indices start at 0 and end at XChildCount - 1.

This property is not available at design time.

Data Type

Integer

XChildElementType Property (JSON Class)

The ElementType property indicates the data type of the element.

Syntax

ANSI (Cross Platform)
int GetXChildElementType(int iXChildIndex);

Unicode (Windows)
INT GetXChildElementType(INT iXChildIndex);

Possible Values

ET_OBJECT(0), 
ET_ARRAY(1), 
ET_STRING(2), 
ET_NUMBER(3), 
ET_BOOL(4), 
ET_NULL(5)

int ipworksmq_json_getxchildelementtype(void* lpObj, int xchildindex);

int GetXChildElementType(int iXChildIndex);

Default Value

Remarks

The XChildElementType property indicates the data type of the element.

Possible values are as follows:

0 (Object)
1 (Array)
2 (String)
3 (Number)
4 (Bool)
5 (Null)
6 (Raw)

The XChildIndex parameter specifies the index of the item in the array. The size of the array is controlled by the XChildCount property.

This property is read-only and not available at design time.

Data Type

Integer

XChildName Property (JSON Class)

The Name property provides the name of the element.

Syntax

ANSI (Cross Platform)
char* GetXChildName(int iXChildIndex);

Unicode (Windows)
LPWSTR GetXChildName(INT iXChildIndex);

char* ipworksmq_json_getxchildname(void* lpObj, int xchildindex);

QString GetXChildName(int iXChildIndex);

Default Value

Remarks

The XChildName property provides the name of the element. For elements within an array, the XChildName property will be empty.

The XChildIndex parameter specifies the index of the item in the array. The size of the array is controlled by the XChildCount property.

This property is read-only and not available at design time.

Data Type

String

XChildXText Property (JSON Class)

This property contains the text of the element.

Syntax

ANSI (Cross Platform)
char* GetXChildXText(int iXChildIndex);

Unicode (Windows)
LPWSTR GetXChildXText(INT iXChildIndex);

char* ipworksmq_json_getxchildxtext(void* lpObj, int xchildindex);

QString GetXChildXText(int iXChildIndex);

Default Value

Remarks

This property contains the text of the element.

The XChildIndex parameter specifies the index of the item in the array. The size of the array is controlled by the XChildCount property.

This property is read-only and not available at design time.

Data Type

String

XElement Property (JSON Class)

This property includes the name of the current element.

Syntax

ANSI (Cross Platform)
char* GetXElement();
int SetXElement(const char* lpszXElement);

Unicode (Windows)
LPWSTR GetXElement();
INT SetXElement(LPCWSTR lpszXElement);

char* ipworksmq_json_getxelement(void* lpObj);
int ipworksmq_json_setxelement(void* lpObj, const char* lpszXElement);

QString GetXElement();
int SetXElement(QString qsXElement);

Default Value

Remarks

This property contains the name of the current element. The current element is specified through the XPath property.

Data Type

String

XElementType Property (JSON Class)

This property indicates the data type of the current element.

Syntax

ANSI (Cross Platform)
int GetXElementType();

Unicode (Windows)
INT GetXElementType();

Possible Values

ET_OBJECT(0), 
ET_ARRAY(1), 
ET_STRING(2), 
ET_NUMBER(3), 
ET_BOOL(4), 
ET_NULL(5)

int ipworksmq_json_getxelementtype(void* lpObj);

int GetXElementType();

Default Value

Remarks

This property specifies the data type of the current element. After setting XPath, this property is populated. Possible values are as follows:

0 (Object)
1 (Array)
2 (String)
3 (Number)
4 (Bool)
5 (Null)
6 (Raw)

Note: This property is not applicable when parsing a document and BuildDOM is False.

This property is read-only.

Data Type

Integer

XErrorPath Property (JSON Class)

This property includes an XPath to check the server response for errors.

Syntax

ANSI (Cross Platform)
char* GetXErrorPath();
int SetXErrorPath(const char* lpszXErrorPath);

Unicode (Windows)
LPWSTR GetXErrorPath();
INT SetXErrorPath(LPCWSTR lpszXErrorPath);

char* ipworksmq_json_getxerrorpath(void* lpObj);
int ipworksmq_json_setxerrorpath(void* lpObj, const char* lpszXErrorPath);

QString GetXErrorPath();
int SetXErrorPath(QString qsXErrorPath);

Default Value

Remarks

This property contains an XPath to check the server response for errors. If the XPath exists, an exception will be thrown containing the value of the element at the path.

Data Type

String

XParent Property (JSON Class)

The parent of the current element.

Syntax

ANSI (Cross Platform)
char* GetXParent();

Unicode (Windows)
LPWSTR GetXParent();

char* ipworksmq_json_getxparent(void* lpObj);

QString GetXParent();

Default Value

Remarks

This property contains the parent of the current element. The current element is specified via the XPath property.

This property is read-only.

Data Type

String

XPath Property (JSON Class)

This property provides a way to point to a specific element in the response.

Syntax

ANSI (Cross Platform)
char* GetXPath();
int SetXPath(const char* lpszXPath);

Unicode (Windows)
LPWSTR GetXPath();
INT SetXPath(LPCWSTR lpszXPath);

char* ipworksmq_json_getxpath(void* lpObj);
int ipworksmq_json_setxpath(void* lpObj, const char* lpszXPath);

QString GetXPath();
int SetXPath(QString qsXPath);

Default Value

Remarks

XPath may be set to navigate to specific elements within the JSON document. This will be the path to a specified value within the document. Because arrays in JSON only contain values, and no associated object name, an empty name will be used for these values. To reach an array element at position 1, the path must be set to "[1]". In addition, a root element named "json" will be added to each JSON document in the parser.

BuildDOM must be set to True before parsing the document for the XPath functionality to be available.

The XPath property accepts both XPath and JSONPath formats. Please review the following notes on both formats.

XPath

The path is a series of one or more element accessors separated by '/'. The path can be absolute (starting with '/') or relative to the current XPath location.

The following are possible values for an element accessor:


'name'	A particular element name.
[i]	The i-th subelement of the current element.
..	the parent of the current element.

When XPath is set to a valid path, the following properties are updated:

XElement
XElementType
XParent
XText
XSubTree
XChildren*

BuildDOM must be set to True before parsing the document for the XPath functionality to be available.

Simple JSON Document

{
  "firstlevel": {
    "one": "value",
    "two": ["first", "second"],
    "three": "value three"
  }
}

Example 1. Setting XPath:


Document root	JsonControl.XPath = "/"
Specific Element	JsonControl.XPath = "/json/firstlevel/one/"
i-th Child	JsonControl.XPath = "/json/firstlevel/two/[i]/"

Note: When using XPath notation, the root element is always referred to as "json". As in the previous examples, this means all paths will begin with "/json".

JSONPath

This property implements a subset of the JSONPath notation. This may be set to point to a specific element in the JSON document.

The JSONPath is a series of one or more accessors in either dot-notation

$.store.book[0].title

or in bracket-notation, as follows:

$['store']['book'][0]['title']

After setting XPath, the following properties are populated:

XChildren
XElement
XElementType
XSubTree
XText

Example 2. Setting JSONPath:

Given the following JSON document:

{
    "store": {
        "book": [
            {
                "category": "reference",
                "author": "Nigel Rees",
                "title": "Sayings of the Century",
                "price": 8.95
            },
            {
                "category": "fiction",
                "author": "Evelyn Waugh",
                "title": "Sword of Honour",
                "price": 12.99
            },
            {
                "category": "fiction",
                "author": "Herman Melville",
                "title": "Moby Dick",
                "isbn": "0-553-21311-3",
                "price": 8.99
            },
            {
                "category": "fiction",
                "author": "J. R. R. Tolkien",
                "title": "The Lord of the Rings",
                "isbn": "0-395-19395-8",
                "price": 22.99
            }
        ],
        "bicycle": {
            "color": "red",
            "price": 19.95
        }
    },
}

The following code shows several examples.

Get the first book's author:

json.XPath = "$.store.book[0].author"; Console.WriteLine(json.XText); //Output //"Nigel Rees" Select the first book and inspect the children:

json.XPath = "$['store']['book'][1]['price']"; Console.WriteLine(json.XText); //Output //12.99 Get the second to last book's author:

json.XPath = "$.store.book[0]"; Console.WriteLine(json.XSubTree); //Output // { // "category": "reference", // "author": "Nigel Rees", // "title": "Sayings of the Century", // "price": 8.95 // }

Data Type

String

XSubTree Property (JSON Class)

This property includes a snapshot of the current element in the document.

Syntax

ANSI (Cross Platform)
char* GetXSubTree();

Unicode (Windows)
LPWSTR GetXSubTree();

char* ipworksmq_json_getxsubtree(void* lpObj);

QString GetXSubTree();

Default Value

Remarks

The current element is specified through this property. For this property to work, you must have the CacheContent set to True.

This property is read-only.

Data Type

String

XText Property (JSON Class)

This property includes the text of the current element.

Syntax

ANSI (Cross Platform)
char* GetXText();
int SetXText(const char* lpszXText);

Unicode (Windows)
LPWSTR GetXText();
INT SetXText(LPCWSTR lpszXText);

char* ipworksmq_json_getxtext(void* lpObj);
int ipworksmq_json_setxtext(void* lpObj, const char* lpszXText);

QString GetXText();
int SetXText(QString qsXText);

Default Value

Remarks

This property contains the text of the current element. The current element is specified through the XPath property.

Data Type

String

Config Method (JSON Class)

Sets or retrieves a configuration setting.

Syntax

ANSI (Cross Platform)
char* Config(const char* lpszConfigurationString);

Unicode (Windows)
LPWSTR Config(LPCWSTR lpszConfigurationString);

char* ipworksmq_json_config(void* lpObj, const char* lpszConfigurationString);

QString Config(const QString& qsConfigurationString);

Remarks

Config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Error Handling (C++)

This method returns a String value; after it returns, call the GetLastErrorCode() method to obtain its result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message.

EndArray Method (JSON Class)

This method writes the closing bracket of a JSON array.

Syntax

ANSI (Cross Platform)
int EndArray();

Unicode (Windows)
INT EndArray();

int ipworksmq_json_endarray(void* lpObj);

int EndArray();

Remarks

This method writes the closing bracket of a JSON array to the output. An array must already have been opened by calling StartArray.

Error Handling (C++)

This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)

EndObject Method (JSON Class)

This method writes the closing brace of a JSON object.

Syntax

ANSI (Cross Platform)
int EndObject();

Unicode (Windows)
INT EndObject();

int ipworksmq_json_endobject(void* lpObj);

int EndObject();

Remarks

This method writes the closing brace of a JSON object. An object must have been started previously by calling StartObject.

Error Handling (C++)

Flush Method (JSON Class)

This method flushes the parser's or writer's buffers.

Syntax

ANSI (Cross Platform)
int Flush();

Unicode (Windows)
INT Flush();

int ipworksmq_json_flush(void* lpObj);

int Flush();

Remarks

When Flush is called, the component flushes all of its buffers, firing events as necessary.

When parsing, the end state of the JSON is checked. If Validate is also True, the parser verifies that all open elements were closed, returning an error if not.

When writing, the resultant JSON is available in one of the output properties.

Output Properties

The class will determine the destination of the output based on which properties are set.

The order in which the output properties are checked is as follows:

OutputFile
OutputData: The output data are written to this property if no other destination is specified.

Error Handling (C++)

HasXPath Method (JSON Class)

Determines whether a specific element exists in the document.

Syntax

ANSI (Cross Platform)
int HasXPath(const char* lpszXPath);

Unicode (Windows)
INT HasXPath(LPCWSTR lpszXPath);

int ipworksmq_json_hasxpath(void* lpObj, const char* lpszXPath);

bool HasXPath(const QString& qsXPath);

Remarks

This method determines whether a particular XPath exists within the document. This may be used to check if a path exists before setting it via XPath.

This method returns True if the xpath exists, False if not.

See XPath for details on the XPath syntax.

Error Handling (C++)

This method returns a Boolean value; after it returns, call the GetLastErrorCode() method to obtain its result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message.

InsertProperty Method (JSON Class)

This method inserts the specified name and value at the selected position.

Syntax

ANSI (Cross Platform)
int InsertProperty(const char* lpszName, const char* lpszValue, int iValueType, int iPosition);

Unicode (Windows)
INT InsertProperty(LPCWSTR lpszName, LPCWSTR lpszValue, INT iValueType, INT iPosition);

int ipworksmq_json_insertproperty(void* lpObj, const char* lpszName, const char* lpszValue, int iValueType, int iPosition);

int InsertProperty(const QString& qsName, const QString& qsValue, int iValueType, int iPosition);

Remarks

This method inserts a property and its corresponding value relative to the element specified by XPath. Before calling this method, a valid JSON document must first be loaded by calling Parse.

The Name parameter specifies the name of the property.

The Value parameter specifies the value of the property.

The ValueType parameter specifies the type of the value. Possible values are as follows:

0 (Object)
1 (Array)
2 (String)
3 (Number)
4 (Bool)
5 (Null)
6 (Raw)

The Position parameter specifies the position of Value relative to the element specified by XPath. Possible values are as follows:

0 (Before the current element)
1 (After the current element)
2 (The first child of the current element)
3 (The last child of the current element)

See Save for details.

Error Handling (C++)

InsertValue Method (JSON Class)

This method inserts the specified value at the selected position.

Syntax

ANSI (Cross Platform)
int InsertValue(const char* lpszValue, int iValueType, int iPosition);

Unicode (Windows)
INT InsertValue(LPCWSTR lpszValue, INT iValueType, INT iPosition);

int ipworksmq_json_insertvalue(void* lpObj, const char* lpszValue, int iValueType, int iPosition);

int InsertValue(const QString& qsValue, int iValueType, int iPosition);

Remarks

This method inserts a value relative to the element specified by XPath. Before calling this method, a valid JSON document must first be loaded by calling Parse.

The Value parameter specifies the value of the property.

The ValueType parameter specifies the type of the value. Possible values are as follows:

0 (Object)
1 (Array)
2 (String)
3 (Number)
4 (Bool)
5 (Null)
6 (Raw)

The Position parameter specifies the position of Value relative to the element specified by XPath. Possible values are as follows:

0 (Before the current element)
1 (After the current element)
2 (The first child of the current element)
3 (The last child of the current element)

See Save for details.

Error Handling (C++)

Parse Method (JSON Class)

This method parses the specified JSON data.

Syntax

ANSI (Cross Platform)
int Parse();

Unicode (Windows)
INT Parse();

int ipworksmq_json_parse(void* lpObj);

int Parse();

Remarks

This method parses the specified JSON data.

The following events will fire during parsing:

StartElement
Characters
EndElement
IgnorableWhitespace

BuildDOM must be set to True before parsing the document for the XPath functionality to be available.

The XPath property accepts both XPath and JSONPath formats. Please review the following notes on both formats.

XPath

The path is a series of one or more element accessors separated by '/'. The path can be absolute (starting with '/') or relative to the current XPath location.

The following are possible values for an element accessor:


'name'	A particular element name.
[i]	The i-th subelement of the current element.
..	the parent of the current element.

When XPath is set to a valid path, the following properties are updated:

XElement
XElementType
XParent
XText
XSubTree
XChildren*

BuildDOM must be set to True before parsing the document for the XPath functionality to be available.

Simple JSON Document

{
  "firstlevel": {
    "one": "value",
    "two": ["first", "second"],
    "three": "value three"
  }
}

Example 1. Setting XPath:


Document root	JsonControl.XPath = "/"
Specific Element	JsonControl.XPath = "/json/firstlevel/one/"
i-th Child	JsonControl.XPath = "/json/firstlevel/two/[i]/"

Note: When using XPath notation, the root element is always referred to as "json". As in the previous examples, this means all paths will begin with "/json".

JSONPath

This property implements a subset of the JSONPath notation. This may be set to point to a specific element in the JSON document.

The JSONPath is a series of one or more accessors in either dot-notation

$.store.book[0].title

or in bracket-notation, as follows:

$['store']['book'][0]['title']

After setting XPath, the following properties are populated:

XChildren
XElement
XElementType
XSubTree
XText

Example 2. Setting JSONPath:

Given the following JSON document:

{
    "store": {
        "book": [
            {
                "category": "reference",
                "author": "Nigel Rees",
                "title": "Sayings of the Century",
                "price": 8.95
            },
            {
                "category": "fiction",
                "author": "Evelyn Waugh",
                "title": "Sword of Honour",
                "price": 12.99
            },
            {
                "category": "fiction",
                "author": "Herman Melville",
                "title": "Moby Dick",
                "isbn": "0-553-21311-3",
                "price": 8.99
            },
            {
                "category": "fiction",
                "author": "J. R. R. Tolkien",
                "title": "The Lord of the Rings",
                "isbn": "0-395-19395-8",
                "price": 22.99
            }
        ],
        "bicycle": {
            "color": "red",
            "price": 19.95
        }
    },
}

The following code shows several examples.

Get the first book's author:

json.XPath = "$.store.book[0].author"; Console.WriteLine(json.XText); //Output //"Nigel Rees" Select the first book and inspect the children:

json.XPath = "$['store']['book'][1]['price']"; Console.WriteLine(json.XText); //Output //12.99 Get the second to last book's author:

json.XPath = "$.store.book[0]"; Console.WriteLine(json.XSubTree); //Output // { // "category": "reference", // "author": "Nigel Rees", // "title": "Sayings of the Century", // "price": 8.95 // }

Input Properties

The class will determine the source of the input based on which properties are set.

The order in which the input properties are checked is as follows:

InputFile
InputData

When a valid source is found, the search stops.

If parsing multiple documents, call Reset between documents to reset the parser.

Error Handling (C++)

PutName Method (JSON Class)

This method writes the name of a property.

Syntax

ANSI (Cross Platform)
int PutName(const char* lpszName);

Unicode (Windows)
INT PutName(LPCWSTR lpszName);

int ipworksmq_json_putname(void* lpObj, const char* lpszName);

int PutName(const QString& qsName);

Remarks

This method writes the name of a property. The Name parameter specifies the value to write.

Error Handling (C++)

PutProperty Method (JSON Class)

This method writes a property and value.

Syntax

ANSI (Cross Platform)
int PutProperty(const char* lpszName, const char* lpszValue, int iValueType);

Unicode (Windows)
INT PutProperty(LPCWSTR lpszName, LPCWSTR lpszValue, INT iValueType);

int ipworksmq_json_putproperty(void* lpObj, const char* lpszName, const char* lpszValue, int iValueType);

int PutProperty(const QString& qsName, const QString& qsValue, int iValueType);

Remarks

This method writes a property and its corresponding value to the output.

The Name parameter specifies the name of the property.

The Value parameter specifies the value of the property.

The ValueType parameter specifies the type of the value. Possible values are as follows:

0 (Object)
1 (Array)
2 (String)
3 (Number)
4 (Bool)
5 (Null)
6 (Raw)

Error Handling (C++)

PutRaw Method (JSON Class)

This method writes a raw JSON fragment.

Syntax

ANSI (Cross Platform)
int PutRaw(const char* lpszText);

Unicode (Windows)
INT PutRaw(LPCWSTR lpszText);

int ipworksmq_json_putraw(void* lpObj, const char* lpszText);

int PutRaw(const QString& qsText);

Remarks

This method writes raw data to the output. This may be used to write any data of any format directly to the output.

Error Handling (C++)

PutValue Method (JSON Class)

This method writes a value of a property.

Syntax

ANSI (Cross Platform)
int PutValue(const char* lpszValue, int iValueType);

Unicode (Windows)
INT PutValue(LPCWSTR lpszValue, INT iValueType);

int ipworksmq_json_putvalue(void* lpObj, const char* lpszValue, int iValueType);

int PutValue(const QString& qsValue, int iValueType);

Remarks

This method writes the value of a property to the output. The Value parameter specifies the value. The ValueType parameter specifies the type of data. Possible values are as follows:

0 (Object)
1 (Array)
2 (String)
3 (Number)
4 (Bool)
5 (Null)
6 (Raw)

Error Handling (C++)

Remove Method (JSON Class)

This method removes the element or value set in XPath.

Syntax

ANSI (Cross Platform)
int Remove();

Unicode (Windows)
INT Remove();

int ipworksmq_json_remove(void* lpObj);

int Remove();

Remarks

This method removes the current object at the specified XPath. This is used when editing previously loaded JSON documents.

See Save for details.

Error Handling (C++)

Reset Method (JSON Class)

This method resets the class.

Syntax

ANSI (Cross Platform)
int Reset();

Unicode (Windows)
INT Reset();

int ipworksmq_json_reset(void* lpObj);

int Reset();

Remarks

This method resets the JSON parser.

Error Handling (C++)

Save Method (JSON Class)

This method saves the modified JSON document.

Syntax

ANSI (Cross Platform)
int Save();

Unicode (Windows)
INT Save();

int ipworksmq_json_save(void* lpObj);

int Save();

Remarks

This method saves the modified JSON data. This is used after editing a previously loaded JSON document.

After loading a JSON document with Parse the document may be edited. The class supports inserting new values, renaming or overwriting existing values, and removing values. After editing is complete, call Save to output the updated JSON document.

The following methods are applicable when modifying a JSON document:

InsertProperty
InsertValue
Remove
Save
SetName
SetValue

When Save is called, the modified JSON is written to the specified output location.

Output Properties

The class will determine the destination of the output based on which properties are set.

The order in which the output properties are checked is as follows:

OutputFile
OutputData: The output data are written to this property if no other destination is specified.

Example 1. Inserting New Values:

The ValueType parameter of these methods specifies the type of the value. Possible values are as follows:

0 (Object)
1 (Array)
2 (String)
3 (Number)
4 (Bool)
5 (Null)
6 (Raw)

The Position parameter of these methods specifies the position of Value. Possible values are as follows:

0 (Before the current element)
1 (After the current element)
2 (The first child of the current element)
3 (The last child of the current element)

For example:

Given the following JSON:

{
    "store": {
        "books": [
            {
                "category": "reference",
                "author": "Nigel Rees",
                "title": "Sayings of the Century",
            },
            {
                "category": "fiction",
                "author": "Evelyn Waugh",
                "title": "Sword of Honour",
            }
        ]    
    }
}

Insert a new property "price" for each book:

Produces the JSON:

{
  "store": {
    "books": [
    {
      "category": "reference",
      "author": "Nigel Rees",
      "title": "Sayings of the Century",
      "price": 8.95
    },
    {
      "category": "fiction",
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 12.99
    }
    ]
  }
}

To add a new book to the array:

Produces the JSON:

{
  "store": {
    "books": [
    {
      "category": "reference",
      "author": "Nigel Rees",
      "title": "Sayings of the Century",
      "price": 8.95
    },
    {
      "category": "fiction",
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 12.99
    },
    {
      "category": "fiction",
      "author": "Herman Melville",
      "title": "Moby Dick",
      "price": 8.99
    }
    ]
  }
}

To add a new array property to each book:

Produces the JSON:

{
  "store": {
    "books": [
    {
      "tags": ["quotes", "british"],
      "category": "reference",
      "author": "Nigel Rees",
      "title": "Sayings of the Century",
      "price": 8.95
    },
    {
      "tags": ["trilogy", "war"],
      "category": "fiction",
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 12.99
    },
    {
      "tags": ["classic", "whales"],
      "category": "fiction",
      "author": "Herman Melville",
      "title": "Moby Dick",
      "price": 8.99
    }
    ]
  }
}

Example 2. Removing Values:

To remove existing values, set XPath and call the Remove method. Continuing with example 1, to remove the first book: json.XPath = "/json/store/books/[1]"; json.Remove(); json.Save();

Produces the JSON:

{
  "store": {
    "books": [
    {
      "tags": ["trilogy", "war"],
      "category": "fiction",
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 12.99
    },
    {
      "tags": ["classic", "whales"],
      "category": "fiction",
      "author": "Herman Melville",
      "title": "Moby Dick",
      "price": 8.99
    }
    ]
  }
}

To remove the "category" properties from each book: json.XPath = "/json/store/books/[1]/category"; json.Remove(); json.XPath = "/json/store/books/[2]/category"; json.Remove(); json.Save();

Produces the JSON:

{
  "store": {
    "books": [
    {
      "tags": ["trilogy", "war"],
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 12.99
    },
    {
      "tags": ["classic", "whales"],
      "author": "Herman Melville",
      "title": "Moby Dick",
      "price": 8.99
    }
    ]
  }
}

Example 3. Updating Existing Names and Values:

Produces the JSON:

{
  "store": {
    "books": [
    {
      "meta": ["trilogy", "war"],
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 13.99
    },
    {
      "meta": ["classic", "revenge"],
      "author": "Herman Melville",
      "title": "Moby Dick",
      "price": 9.99
    }
    ]
  }
}

Error Handling (C++)

SetInputStream Method (JSON Class)

Sets the stream from which the class will read data to parse.

Syntax

ANSI (Cross Platform)
int SetInputStream(IPWorksMQStream* sInputStream);

Unicode (Windows)
INT SetInputStream(IPWorksMQStream* sInputStream);

int ipworksmq_json_setinputstream(void* lpObj, IPWorksMQStream* sInputStream);

int SetInputStream(IPWorksMQStream* sInputStream);

Remarks

This method specifies a stream from which data will be read when Parse is called.

Input Properties

The class will determine the source of the input based on which properties are set.

The order in which the input properties are checked is as follows:

InputFile
InputData

When a valid source is found, the search stops.

Error Handling (C++)

SetName Method (JSON Class)

This method sets a new name for the element specified by XPath.

Syntax

ANSI (Cross Platform)
int SetName(const char* lpszName);

Unicode (Windows)
INT SetName(LPCWSTR lpszName);

int ipworksmq_json_setname(void* lpObj, const char* lpszName);

int SetName(const QString& qsName);

Remarks

This method sets a new name for the element specified in XPath. This is used to modify an existing JSON document.

The Name parameter specifies the new name of the element.

See Save for details.

Error Handling (C++)

SetOutputStream Method (JSON Class)

This method sets the stream to which the class will write the JSON.

Syntax

ANSI (Cross Platform)
int SetOutputStream(IPWorksMQStream* sOutputStream);

Unicode (Windows)
INT SetOutputStream(IPWorksMQStream* sOutputStream);

int ipworksmq_json_setoutputstream(void* lpObj, IPWorksMQStream* sOutputStream);

int SetOutputStream(IPWorksMQStream* sOutputStream);

Remarks

This method sets the stream to which the output will be written when writing data.

Output Properties

The class will determine the destination of the output based on which properties are set.

The order in which the output properties are checked is as follows:

OutputFile
OutputData: The output data are written to this property if no other destination is specified.

Error Handling (C++)

SetValue Method (JSON Class)

This method sets a new value for the element specified by XPath.

Syntax

ANSI (Cross Platform)
int SetValue(const char* lpszValue, int iValueType);

Unicode (Windows)
INT SetValue(LPCWSTR lpszValue, INT iValueType);

int ipworksmq_json_setvalue(void* lpObj, const char* lpszValue, int iValueType);

int SetValue(const QString& qsValue, int iValueType);

Remarks

This method sets a new value for the element specified in XPath. This is used to modify an existing JSON document.

Value specifies the new value.

ValueType specifies the type of the value. Possible values are as follows:

0 (Object)
1 (Array)
2 (String)
3 (Number)
4 (Bool)
5 (Null)
6 (Raw)

See Save for details.

Error Handling (C++)

StartArray Method (JSON Class)

This method writes the opening bracket of a JSON array.

Syntax

ANSI (Cross Platform)
int StartArray();

Unicode (Windows)
INT StartArray();

int ipworksmq_json_startarray(void* lpObj);

int StartArray();

Remarks

This method writes the opening bracket of a JSON array to the output. To close the array, call EndArray.

Error Handling (C++)

StartObject Method (JSON Class)

This event writes the opening brace of a JSON object.

Syntax

ANSI (Cross Platform)
int StartObject();

Unicode (Windows)
INT StartObject();

int ipworksmq_json_startobject(void* lpObj);

int StartObject();

Remarks

This method writes the opening brace of a JSON object to the output. To close the object, call EndObject.

Error Handling (C++)

TryXPath Method (JSON Class)

Navigates to the specified XPath if it exists.

Syntax

ANSI (Cross Platform)
int TryXPath(const char* lpszxpath);

Unicode (Windows)
INT TryXPath(LPCWSTR lpszxpath);

int ipworksmq_json_tryxpath(void* lpObj, const char* lpszxpath);

bool TryXPath(const QString& qsxpath);

Remarks

This method will attempt to navigate to the specified XPath parameter if it exists within the document.

If the XPath exists the XPath property will be updated and this method returns True.

If the XPath does not exist the XPath property is not updated and this method returns False.

Error Handling (C++)

Characters Event (JSON Class)

This event is fired for plaintext segments of the input stream.

Syntax

ANSI (Cross Platform)
virtual int FireCharacters(JSONCharactersEventParams *e);

typedef struct {
  const char *Text;
  int reserved;
} JSONCharactersEventParams;


Unicode (Windows)
virtual INT FireCharacters(JSONCharactersEventParams *e);

typedef struct {
  LPCWSTR Text;
  INT reserved;
} JSONCharactersEventParams;

#define EID_JSON_CHARACTERS 1

virtual INT IPWORKSMQ_CALL FireCharacters(LPSTR &lpszText);

class JSONCharactersEventParams {
public:
  const QString &Text();

  int EventRetVal();
  void SetEventRetVal(int iRetVal);
};

// To handle, connect one or more slots to this signal.
void Characters(JSONCharactersEventParams *e);

// Or, subclass JSON and override this emitter function.
virtual int FireCharacters(JSONCharactersEventParams *e) {...}

Remarks

The Characters event provides the plaintext content of the JSON document (i.e., the text inside the elements). The text is provided through the Text parameter.

The text includes white space as well as end-of-line characters, except for ignorable whitespace, which is fired through the IgnorableWhitespace event.

EndDocument Event (JSON Class)

This event fires when the end of a JSON document is encountered.

Syntax

ANSI (Cross Platform)
virtual int FireEndDocument(JSONEndDocumentEventParams *e);

typedef struct {
  int reserved;
} JSONEndDocumentEventParams;


Unicode (Windows)
virtual INT FireEndDocument(JSONEndDocumentEventParams *e);

typedef struct {
  INT reserved;
} JSONEndDocumentEventParams;

#define EID_JSON_ENDDOCUMENT 2

virtual INT IPWORKSMQ_CALL FireEndDocument();

class JSONEndDocumentEventParams {
public:
  int EventRetVal();
  void SetEventRetVal(int iRetVal);
};

// To handle, connect one or more slots to this signal.
void EndDocument(JSONEndDocumentEventParams *e);

// Or, subclass JSON and override this emitter function.
virtual int FireEndDocument(JSONEndDocumentEventParams *e) {...}

Remarks

This event fires when parsing of a JSON document ends. This event may fire multiple times if InputFormat is set to a value that accepts multiple JSON documents.

EndElement Event (JSON Class)

This event is fired when an end-element tag is encountered.

Syntax

ANSI (Cross Platform)
virtual int FireEndElement(JSONEndElementEventParams *e);

typedef struct {
  const char *Element;
  int reserved;
} JSONEndElementEventParams;


Unicode (Windows)
virtual INT FireEndElement(JSONEndElementEventParams *e);

typedef struct {
  LPCWSTR Element;
  INT reserved;
} JSONEndElementEventParams;

#define EID_JSON_ENDELEMENT 3

virtual INT IPWORKSMQ_CALL FireEndElement(LPSTR &lpszElement);

class JSONEndElementEventParams {
public:
  const QString &Element();

  int EventRetVal();
  void SetEventRetVal(int iRetVal);
};

// To handle, connect one or more slots to this signal.
void EndElement(JSONEndElementEventParams *e);

// Or, subclass JSON and override this emitter function.
virtual int FireEndElement(JSONEndElementEventParams *e) {...}

Remarks

The EndElement event is fired when the end of an element is found in the document.

The element name is provided by the Element parameter.

Error Event (JSON Class)

Fired when information is available about errors during data delivery.

Syntax

ANSI (Cross Platform)
virtual int FireError(JSONErrorEventParams *e);

typedef struct {
  int ErrorCode;
  const char *Description;
  int reserved;
} JSONErrorEventParams;


Unicode (Windows)
virtual INT FireError(JSONErrorEventParams *e);

typedef struct {
  INT ErrorCode;
  LPCWSTR Description;
  INT reserved;
} JSONErrorEventParams;

#define EID_JSON_ERROR 4

virtual INT IPWORKSMQ_CALL FireError(INT &iErrorCode, LPSTR &lpszDescription);

class JSONErrorEventParams {
public:
  int ErrorCode();

  const QString &Description();

  int EventRetVal();
  void SetEventRetVal(int iRetVal);
};

// To handle, connect one or more slots to this signal.
void Error(JSONErrorEventParams *e);

// Or, subclass JSON and override this emitter function.
virtual int FireError(JSONErrorEventParams *e) {...}

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the class fails with an error.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

IgnorableWhitespace Event (JSON Class)

This event is fired when a section of ignorable whitespace is encountered.

Syntax

ANSI (Cross Platform)
virtual int FireIgnorableWhitespace(JSONIgnorableWhitespaceEventParams *e);

typedef struct {
  const char *Text;
  int reserved;
} JSONIgnorableWhitespaceEventParams;


Unicode (Windows)
virtual INT FireIgnorableWhitespace(JSONIgnorableWhitespaceEventParams *e);

typedef struct {
  LPCWSTR Text;
  INT reserved;
} JSONIgnorableWhitespaceEventParams;

#define EID_JSON_IGNORABLEWHITESPACE 5

virtual INT IPWORKSMQ_CALL FireIgnorableWhitespace(LPSTR &lpszText);

class JSONIgnorableWhitespaceEventParams {
public:
  const QString &Text();

  int EventRetVal();
  void SetEventRetVal(int iRetVal);
};

// To handle, connect one or more slots to this signal.
void IgnorableWhitespace(JSONIgnorableWhitespaceEventParams *e);

// Or, subclass JSON and override this emitter function.
virtual int FireIgnorableWhitespace(JSONIgnorableWhitespaceEventParams *e) {...}

Remarks

The ignorable whitespace section is provided by the Text parameter.

JSON Event (JSON Class)

This event fires with the JSON data being written.

Syntax

ANSI (Cross Platform)
virtual int FireJSON(JSONJSONEventParams *e);

typedef struct {
  const char *Text;
  int reserved;
} JSONJSONEventParams;


Unicode (Windows)
virtual INT FireJSON(JSONJSONEventParams *e);

typedef struct {
  LPCWSTR Text;
  INT reserved;
} JSONJSONEventParams;

#define EID_JSON_JSON 6

virtual INT IPWORKSMQ_CALL FireJSON(LPSTR &lpszText);

class JSONJSONEventParams {
public:
  const QString &Text();

  int EventRetVal();
  void SetEventRetVal(int iRetVal);
};

// To handle, connect one or more slots to this signal.
void JSONEvt(JSONJSONEventParams *e);

// Or, subclass JSON and override this emitter function.
virtual int FireJSON(JSONJSONEventParams *e) {...}

Remarks

This event fires when output data are written.

Text contains the JSON data currently being written.

StartDocument Event (JSON Class)

This event fires when the start of a new JSON document is encountered.

Syntax

ANSI (Cross Platform)
virtual int FireStartDocument(JSONStartDocumentEventParams *e);

typedef struct {
  int reserved;
} JSONStartDocumentEventParams;


Unicode (Windows)
virtual INT FireStartDocument(JSONStartDocumentEventParams *e);

typedef struct {
  INT reserved;
} JSONStartDocumentEventParams;

#define EID_JSON_STARTDOCUMENT 7

virtual INT IPWORKSMQ_CALL FireStartDocument();

class JSONStartDocumentEventParams {
public:
  int EventRetVal();
  void SetEventRetVal(int iRetVal);
};

// To handle, connect one or more slots to this signal.
void StartDocument(JSONStartDocumentEventParams *e);

// Or, subclass JSON and override this emitter function.
virtual int FireStartDocument(JSONStartDocumentEventParams *e) {...}

Remarks

This event fires when parsing of a JSON document begins. This event may fire multiple times if InputFormat is set to a value that accepts multiple JSON documents.

StartElement Event (JSON Class)

This event is fired when a new element is encountered in the document.

Syntax

ANSI (Cross Platform)
virtual int FireStartElement(JSONStartElementEventParams *e);

typedef struct {
  const char *Element;
  int reserved;
} JSONStartElementEventParams;


Unicode (Windows)
virtual INT FireStartElement(JSONStartElementEventParams *e);

typedef struct {
  LPCWSTR Element;
  INT reserved;
} JSONStartElementEventParams;

#define EID_JSON_STARTELEMENT 8

virtual INT IPWORKSMQ_CALL FireStartElement(LPSTR &lpszElement);

class JSONStartElementEventParams {
public:
  const QString &Element();

  int EventRetVal();
  void SetEventRetVal(int iRetVal);
};

// To handle, connect one or more slots to this signal.
void StartElement(JSONStartElementEventParams *e);

// Or, subclass JSON and override this emitter function.
virtual int FireStartElement(JSONStartElementEventParams *e) {...}

Remarks

The StartElement event is fired when a new element is found in the document.

The element name is provided through the Element parameter.

IPWorksMQStream Type

Syntax

IPWorksMQStream (declared in ipworksmq.h)

Remarks

The JSON class includes one or more API members that take a stream object as a parameter. To use such API members, create a concrete class that implements the IPWorksMQStream interface and pass the JSON class an instance of that concrete class.

When implementing the IPWorksMQStream interface's properties and methods, they must behave as described below. If the concrete class's implementation does not behave as expected, undefined behavior may occur.

Properties

CanRead	Whether the stream supports reading. bool CanRead() { return true; }
CanSeek	Whether the stream supports seeking. bool CanSeek() { return true; }
CanWrite	Whether the stream supports writing. bool CanWrite() { return true; }
Length	Gets the length of the stream, in bytes. int64 GetLength() = 0;
Methods

Close	Closes the stream, releasing all resources currently allocated for it. void Close() {} This method is called automatically when an IPWorksMQStream object is deleted.
Flush	Forces all data held by the stream's buffers to be written out to storage. int Flush() { return 0; } Must return `0` if flushing is successful; or `-1` if an error occurs or the stream is closed. If the stream does not support writing, this method must do nothing and return `0`.
Read	Reads a sequence of bytes from the stream and advances the current position within the stream by the number of bytes read. int Read(void* buffer, int count) = 0; `Buffer` specifies the buffer to populate with data from the stream. `Count` specifies the number of bytes that should be read from the stream. Must return the total number of bytes read into `Buffer`; this may be less than `Count` if that many bytes are not currently available, or `0` if the end of the stream has been reached. Must return `-1` if an error occurs, if reading is not supported, or if the stream is closed.
Seek	Sets the current position within the stream based on a particular point of origin. int64 Seek(int64 offset, int seekOrigin) = 0; `Offset` specifies the offset in the stream to seek to, relative to `SeekOrigin`. Valid values for `SeekOrigin` are: `0`: Seek from beginning. `1`: Seek from current position. `2`: Seek from end. Must return the new position within the stream; or `-1` if an error occurs, if seeking is not supported, or if the stream is closed (however, see note below). If `-1` is returned, the current position within the stream must remain unchanged. Note: If the stream is not closed, it must always be possible to call this method with an `Offset` of `0` and a `SeekOrigin` of `1` to obtain the current position within the stream, even if seeking is not otherwise supported.
Write	Writes a sequence of bytes to the stream and advances the current position within the stream by the number of bytes written. int Write(const void* buffer, int count) = 0; `Buffer` specifies the buffer with data to write to the stream. `Count` specifies the number of bytes that should be written to the stream. Must return the total number of bytes written to the stream; this may be less than `Count` if that many bytes could not be written. Must return `-1` if an error occurs, if writing is not supported, or if the stream is closed.

Config Settings (JSON Class)

The class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

JSON Config Settings

CacheContent: If true, the original JSON is stored internally in a buffer.

This configuration setting controls whether or not the class retains the entire original JSON data in a buffer. This is used to retain the original JSON as opposed to returning generated JSON after parsing. The default value is True.

CloseInputStreamAfterProcess: Determines whether or not the input stream is closed after processing.

This configuration setting determines whether or not the input stream set by SetInputStream is closed after processing is complete. The default value is True.

CloseOutputStreamAfterProcess: Determines whether or not the output stream is closed after processing.

This configuration setting determines whether or not the output stream set by SetOutputStream is closed after processing is complete. The default value is True.

ElementXPath: The XPath value for the current element in the document.

This configuration setting holds the current XPath value when the document is parsed. When queried from inside the StartElement event, the corresponding element's XPath value will be returned. For instance:

string elementXPath = json.Config("ElementXPath");

Note: The BuildDOM property must be set to False.

EscapeForwardSlashes: Whether to escape forward slashes when writing a JSON object.

This configuration setting specifies whether forward slashes (/) are escaped when creating a JSON object using the class. This does not affect parsing of JSON. It is applicable only when JSON values are written.

InputFormat: Specifies the input format used in JSON streaming.

This configuration setting specifies how JSON documents are formatted as they are input to the class. This setting is designed for use when data are provided via JSON streaming. This means multiple documents may be parsed by the class. This setting is applicable only when BuildDOM is set to False. Possible values are as follows:


Value	Description
0 (None - default)	Only a single JSON document is expected. Use this when a single JSON document is being parsed (most cases).
1 (Line Delimited)	Multiple documents are separated by carriage return (CR), line feed (LF), or CRLF character sequences.
2 (Record Separated)	A defined start and end delimiter separate documents. See RecordStartDelimiter and RecordEndDelimiter.
3 (Concatenated)	New documents begin immediately after the previous documents end; no characters or delimiters separate the documents.

PrettyPrint: Determines whether output is on one line or "pretty printed".

The value of this configuration setting determines whether output is generated as a single line of JSON or as multiple "pretty printed" lines. The following example code, provides a better understanding of this configuration setting: json.Config("PrettyPrint=true"); // false json.StartObject(); json.PutName("data"); json.StartObject(); json.PutProperty("id", "3", 3); json.PutProperty("first_name", "Emma", 2); json.PutProperty("last_name", "Wong", 2); json.PutProperty("avatar", "https://s3.amazonaws.com/uifaces/faces/twitter/olegpogodaev/128.jpg", 2); json.EndObject(); json.EndObject(); json.Flush(); Console.WriteLine(json.OutputData); With PrettyPrint set to False (the default), the output would look like this:

{"data":{"id":3,"first_name":"Emma","last_name":"Wong","avatar":"https:\/\/s3.amazonaws.com\/uifaces\/faces\/twitter\/olegpogodaev\/128.jpg"}}

With PrettyPrint set to True, the output instead would look like this:

{
  "data": {
    "id": 3,
    "first_name": "Emma",
    "last_name": "Wong",
    "avatar": "https:\/\/s3.amazonaws.com\/uifaces\/faces\/twitter\/olegpogodaev\/128.jpg"
  }
}

The default value is False.

RecordEndDelimiter: The character sequence after the end of a JSON document.

This configuration setting is used in conjunction with InputFormat to specify the character sequence that is expected after the end of a JSON document.

RecordStartDelimiter: The character sequence before the start of a JSON document.

This configuration setting is used in conjunction with InputFormat to specify the character sequence that is expected before the start of a JSON document.

StringProcessingOptions: Defines options to use when processing string values.

This configuration setting determines what additional processing is performed on string values during parsing. By default, no additional processing is performed and the string is returned as is from the document. Strings also may be unquoted, unescaped, or both. Possible values follow:


0 (none - default)	No additional processing is performed.
1 (unquote)	Strings are unquoted.
2 (unescape)	Any escaped sequences are unescaped.
3 (unquote and unescape)	Values are both unquoted and unescaped.

For instance, given the JSON element:

"example" : "value\ntest"

The following table shows the resulting value for the XText of the element:


StringProcessingOption	Output
0 (none)	"value\ntest"
1 (unquote)	value\ntest
2 (unescape)	"value test"
3 (unquote and unescape)	value test

XPathNotation: Specifies the expected format when setting XPath.

This configuration setting optionally specifies the expected input format when setting XPath. Possible values follow:

0 (Auto - default)
1 (XPath)
2 (JSONPath)

In most cases, the default of 0 (Auto) is sufficient. The class will determine whether the path value is in XPath or JSONPath format automatically. If desired, the type may be explicitly set to either XPath or JSONPath using the values above.

Trappable Errors (JSON Class)

Error Handling (C++)

Call the GetLastErrorCode() method to obtain the last called method's result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. Known error codes are listed below. If an error occurs, the GetLastError() method can be called to retrieve the associated error message.

JSON Errors


	10231 Unbalanced element tag.
	10232 Invalid JSON markup.
	10233 Invalid XPath.
	10234 DOM tree unavailable (set BuildDOM to True and reparse).

XML Errors


	101 Invalid attribute index.
	102 No attributes available.
	103 Invalid namespace index.
	104 No namespaces available.
	105 Invalid element index.
	106 No elements available.
	107 Attribute does not exist.
	201 Unbalanced element tag.
	202 Unknown element prefix (can't find namespace).
	203 Unknown attribute prefix (can't find namespace).
	204 Invalid XML markup.
	205 Invalid end state for parser.
	206 Document contains unbalanced elements.
	207 Invalid XPath.
	208 No such child.
	209 Top element does not match start of path.
	210 DOM tree unavailable (set BuildDOM to true and reparse).
	302 Can't open file.
	401 Invalid XML would be generated.
	402 An invalid XML name has been specified.