JSON Class

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

Syntax

class ipworksmq.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, build_dom 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 build_dom is True (default). If build_dom is False, parsed data are accessible only through the events.

The following events will fire during parsing:

• on_start_element
• on_characters
• on_end_element
• on_ignorable_whitespace

If build_dom 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.

build_dom 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:

• xelement
• xelement_type
• xparent
• xtext
• xsub_tree
• xchildren

build_dom 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"
  }
}

JSONPath

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

$.store.book[0].title

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

After setting xpath, the following properties are populated:

• xchildren
• xelement
• xelement_type
• xsub_tree
• xtext

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
        }
    },
}

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:

• input_file
• input_data

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 on_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:

• output_file
• output_data: 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:

• insert_property
• insert_value
• remove
• save
• set_name
• set_value

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:

• output_file
• output_data: 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 insert_property or insert_value 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 set_name and set_value 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.

Method List

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

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.

Config Settings

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

build_dom Property

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

Syntax

def get_build_dom() -> bool: ...
def set_build_dom(value: bool) -> None: ...

build_dom = property(get_build_dom, set_build_dom)

Default Value

TRUE

Remarks

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

input_data Property

This property includes the JSON data to parse.

Syntax

def get_input_data() -> str: ...
def set_input_data(value: str) -> None: ...

input_data = property(get_input_data, set_input_data)

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:

• input_file
• input_data

input_file Property

This property specifies the file to process.

Syntax

def get_input_file() -> str: ...
def set_input_file(value: str) -> None: ...

input_file = property(get_input_file, set_input_file)

Default Value

""

Remarks

This property specifies the file to be processed. Set this property to the full or relative path to the file that 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:

• input_file
• input_data

output_data Property

This property includes the output JSON after processing.

Syntax

def get_output_data() -> str: ...
def set_output_data(value: str) -> None: ...

output_data = property(get_output_data, set_output_data)

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:

• output_file
• output_data: The output data are written to this property if no other destination is specified.

output_file Property

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

Syntax

def get_output_file() -> str: ...
def set_output_file(value: str) -> None: ...

output_file = property(get_output_file, set_output_file)

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:

• output_file
• output_data: The output data are written to this property if no other destination is specified.

overwrite Property

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

Syntax

def get_overwrite() -> bool: ...
def set_overwrite(value: bool) -> None: ...

overwrite = property(get_overwrite, set_overwrite)

Default Value

FALSE

Remarks

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

validate Property

This property controls whether documents are validated during parsing.

Syntax

def get_validate() -> bool: ...
def set_validate(value: bool) -> None: ...

validate = property(get_validate, set_validate)

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 in which data can still be parsed even if the document is not well formed.

xchild_count Property

The number of records in the XChild arrays.

Syntax

def get_xchild_count() -> int: ...
def set_xchild_count(value: int) -> None: ...

xchild_count = property(get_xchild_count, set_xchild_count)

Default Value

0

Remarks

This property controls the size of the following arrays:

• xchild_element_type
• xchild_name
• xchild_x_text

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

xchild_element_type Property

The ElementType property indicates the data type of the element.

Syntax

def get_xchild_element_type(xchild_index: int) -> int: ...

Default Value

0

Remarks

The xchild_element_type 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 xchild_index parameter specifies the index of the item in the array. The size of the array is controlled by the xchild_count property.

This property is read-only.

xchild_name Property

The Name property provides the name of the element.

Syntax

def get_xchild_name(xchild_index: int) -> str: ...

Default Value

""

Remarks

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

The xchild_index parameter specifies the index of the item in the array. The size of the array is controlled by the xchild_count property.

This property is read-only.

xchild_x_text Property

This property contains the text of the element.

Syntax

def get_xchild_x_text(xchild_index: int) -> str: ...

Default Value

""

Remarks

This property contains the text of the element.

The xchild_index parameter specifies the index of the item in the array. The size of the array is controlled by the xchild_count property.

This property is read-only.

xelement Property

This property includes the name of the current element.

Syntax

def get_xelement() -> str: ...
def set_xelement(value: str) -> None: ...

xelement = property(get_xelement, set_xelement)

Default Value

""

Remarks

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

xelement_type Property

This property indicates the data type of the current element.

Syntax

def get_xelement_type() -> int: ...

xelement_type = property(get_xelement_type, None)

Default Value

0

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 build_dom is False.

This property is read-only.

xerror_path Property

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

Syntax

def get_xerror_path() -> str: ...
def set_xerror_path(value: str) -> None: ...

xerror_path = property(get_xerror_path, set_xerror_path)

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.

xparent Property

The parent of the current element.

Syntax

def get_xparent() -> str: ...

xparent = property(get_xparent, None)

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.

xpath Property

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

Syntax

def get_xpath() -> str: ...
def set_xpath(value: str) -> None: ...

xpath = property(get_xpath, set_xpath)

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.

build_dom 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:

• xelement
• xelement_type
• xparent
• xtext
• xsub_tree
• xchildren

build_dom 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"
  }
}

JSONPath

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

$.store.book[0].title

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

After setting xpath, the following properties are populated:

• xchildren
• xelement
• xelement_type
• xsub_tree
• xtext

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
        }
    },
}

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 // }

xsub_tree Property

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

Syntax

def get_xsub_tree() -> str: ...

xsub_tree = property(get_xsub_tree, None)

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.

xtext Property

This property includes the text of the current element.

Syntax

def get_xtext() -> str: ...
def set_xtext(value: str) -> None: ...

xtext = property(get_xtext, set_xtext)

Default Value

""

Remarks

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

config Method

Sets or retrieves a configuration setting.

Syntax

def config(configuration_string: str) -> str: ...

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.

end_array Method

This method writes the closing bracket of a JSON array.

Syntax

def end_array() -> None: ...

Remarks

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

end_object Method

This method writes the closing brace of a JSON object.

Syntax

def end_object() -> None: ...

Remarks

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

flush Method

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

Syntax

def flush() -> None: ...

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:

• output_file
• output_data: The output data are written to this property if no other destination is specified.

has_xpath Method

This method determines whether a specific element exists in the document.

Syntax

def has_xpath(xpath: str) -> bool: ...

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 through xpath.

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

See xpath for details on the XPath syntax.

insert_property Method

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

Syntax

def insert_property(name: str, value: str, value_type: int, position: int) -> None: ...

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.

insert_value Method

This method inserts the specified value at the selected position.

Syntax

def insert_value(value: str, value_type: int, position: int) -> None: ...

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.

parse Method

This method parses the specified JSON data.

Syntax

def parse() -> None: ...

Remarks

This method parses the specified JSON 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 build_dom is True (default). If build_dom is False, parsed data are accessible only through the events.

The following events will fire during parsing:

• on_start_element
• on_characters
• on_end_element
• on_ignorable_whitespace

If build_dom 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.

build_dom 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:

• xelement
• xelement_type
• xparent
• xtext
• xsub_tree
• xchildren

build_dom 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"
  }
}

JSONPath

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

$.store.book[0].title

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

After setting xpath, the following properties are populated:

• xchildren
• xelement
• xelement_type
• xsub_tree
• xtext

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
        }
    },
}

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:

• input_file
• input_data

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

put_name Method

This method writes the name of a property.

Syntax

def put_name(name: str) -> None: ...

Remarks

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

put_property Method

This method writes a property and value.

Syntax

def put_property(name: str, value: str, value_type: int) -> None: ...

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)

put_raw Method

This method writes a raw JSON fragment.

Syntax

def put_raw(text: str) -> None: ...

Remarks

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

put_value Method

This method writes a value of a property.

Syntax

def put_value(value: str, value_type: int) -> None: ...

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)

remove Method

This method removes the element or value set in XPath.

Syntax

def remove() -> None: ...

Remarks

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

See save for details.

reset Method

This method resets the class.

Syntax

def reset() -> None: ...

Remarks

This method resets the JSON parser.

save Method

This method saves the modified JSON document.

Syntax

def save() -> None: ...

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:

• insert_property
• insert_value
• remove
• save
• set_name
• set_value

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:

• output_file
• output_data: 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 insert_property or insert_value 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 set_name and set_value 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
    }
    ]
  }
}

set_name Method

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

Syntax

def set_name(name: str) -> None: ...

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.

set_value Method

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

Syntax

def set_value(value: str, value_type: int) -> None: ...

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.

start_array Method

This method writes the opening bracket of a JSON array.

Syntax

def start_array() -> None: ...

Remarks

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

start_object Method

This event writes the opening brace of a JSON object.

Syntax

def start_object() -> None: ...

Remarks

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

try_xpath Method

This method navigates to the specified XPath if it exists.

Syntax

def try_xpath(xpath: str) -> bool: ...

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.

on_characters Event

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

Syntax

class JSONCharactersEventParams(object):
  @property
  def text() -> str: ...

# In class JSON:
@property
def on_characters() -> Callable[[JSONCharactersEventParams], None]: ...
@on_characters.setter
def on_characters(event_hook: Callable[[JSONCharactersEventParams], None]) -> None: ...

Remarks

The on_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 on_ignorable_whitespace event.

on_end_document Event

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

Syntax

class JSONEndDocumentEventParams(object):
# In class JSON:
@property
def on_end_document() -> Callable[[JSONEndDocumentEventParams], None]: ...
@on_end_document.setter
def on_end_document(event_hook: Callable[[JSONEndDocumentEventParams], None]) -> None: ...

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.

on_end_element Event

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

Syntax

class JSONEndElementEventParams(object):
  @property
  def element() -> str: ...

# In class JSON:
@property
def on_end_element() -> Callable[[JSONEndElementEventParams], None]: ...
@on_end_element.setter
def on_end_element(event_hook: Callable[[JSONEndElementEventParams], None]) -> None: ...

Remarks

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

The element name is provided by the Element parameter.

on_error Event

Fired when information is available about errors during data delivery.

Syntax

class JSONErrorEventParams(object):
  @property
  def error_code() -> int: ...

  @property
  def description() -> str: ...

# In class JSON:
@property
def on_error() -> Callable[[JSONErrorEventParams], None]: ...
@on_error.setter
def on_error(event_hook: Callable[[JSONErrorEventParams], None]) -> None: ...

Remarks

The on_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.

on_ignorable_whitespace Event

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

Syntax

class JSONIgnorableWhitespaceEventParams(object):
  @property
  def text() -> str: ...

# In class JSON:
@property
def on_ignorable_whitespace() -> Callable[[JSONIgnorableWhitespaceEventParams], None]: ...
@on_ignorable_whitespace.setter
def on_ignorable_whitespace(event_hook: Callable[[JSONIgnorableWhitespaceEventParams], None]) -> None: ...

Remarks

The ignorable whitespace section is provided by the Text parameter.

on_json Event

This event fires with the JSON data being written.

Syntax

class JSONJSONEventParams(object):
  @property
  def text() -> str: ...

# In class JSON:
@property
def on_json() -> Callable[[JSONJSONEventParams], None]: ...
@on_json.setter
def on_json(event_hook: Callable[[JSONJSONEventParams], None]) -> None: ...

Remarks

This event fires when output data are written.

Text contains the JSON data currently being written.

on_start_document Event

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

Syntax

class JSONStartDocumentEventParams(object):
# In class JSON:
@property
def on_start_document() -> Callable[[JSONStartDocumentEventParams], None]: ...
@on_start_document.setter
def on_start_document(event_hook: Callable[[JSONStartDocumentEventParams], None]) -> None: ...

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.

on_start_element Event

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

Syntax

class JSONStartElementEventParams(object):
  @property
  def element() -> str: ...

# In class JSON:
@property
def on_start_element() -> Callable[[JSONStartElementEventParams], None]: ...
@on_start_element.setter
def on_start_element(event_hook: Callable[[JSONStartElementEventParams], None]) -> None: ...

Remarks

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

The element name is provided through the Element parameter.

JSON Config Settings

JSON Config Settings

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

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

"example" : "value\ntest"

"value\ntest"

value\ntest

"value
test"

value
test

JSON Errors

JSON Errors

XML Errors