MIME Component

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The MIME component allows for the simple encoding and decoding of MIME structures, such as message attachments and file uploads.

Syntax

TipwMIME

Remarks

The component may be used for decoding or encoding of messages. Message holds the content of the encoded message or the filename that holds the encoded data. The decoded data are provided in Parts properties.

To decode a MIME message, you should first assign either the whole message (headers and body) to Message or put the message headers into the MessageHeaders property and the message body or the filename holding it into the Message property. Calling DecodeFromFile or DecodeFromString directs the component to start parsing the message: it will fill out the ContentType and ContentTypeAttr properties with message content-type information, and it will enter information about message parts into the Parts properties, which includes part sizes, part content types, part content type attributes, part content disposition, part content disposition attributes, part encoding, part name, part filename, part headers, or part content (part-decoded string or part-decoded file) for each decoded part.

Calling the DecodeFromString or DecodeFromFile to decode does not actually decode the message but only parses it. The real decoding is done when the part content in the Parts properties is first accessed.

To encode data into a MIME message, you should first assign values for each part to either a part-decoded string or a part- decoded file in the Parts properties property, and optionally assign values to the other part attributes in the Parts properties. Assigning a value to the part-decoded string or a part-decoded file through the Parts properties, fills out automatically the part headers into the Parts properties for the respective part. Calling EncodeToFile or EncodeToString directs the component to fill out the Message with the message body and the MessageHeaders with the headers.

The Progress event is fired as the message is parsed and the data are decoded/encoded.

Property List

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

Method List

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

Event List

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

Config Settings

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

Boundary Property (MIME Component)

This property includes the boundary separating the MIME parts. It has a maximum length of 80 bytes.

Syntax

property Boundary: String read get_Boundary write set_Boundary;

Default Value

''

Remarks

This property contains the boundary separating the MIME parts and has a maximum length of 80 bytes. The component automatically generates a random boundary value during encoding, if no value is given. During decoding, this property is filled with the boundary from the actual MIME message.

The component will truncate any string longer than 80 bytes if assigned to Boundary.

ContentType Property (MIME Component)

This property includes the value of the content-type header of the message that was encoded/decoded.

Syntax

property ContentType: String read get_ContentType write set_ContentType;

Default Value

''

Remarks

This property contains the value of the content-type header of the message that was encoded/decoded. The component filters it out from the MessageHeaders. It shows the user information about the type of the parts and their relation to each other.

The content-type attributes, such as filename, boundary, and charset, are held in this property.

ContentTypeAttr Property (MIME Component)

This property includes the attributes of the content-type header of the message that was encoded or decoded.

Syntax

property ContentTypeAttr: String read get_ContentTypeAttr write set_ContentTypeAttr;

Default Value

''

Remarks

This property contains content-type attributes such as "filename", "boundary", and "charset".

Message Property (MIME Component)

This property contains the encoded message text or a path to a file that contains the encoded message text.

Syntax

property Message: String read get_Message write set_Message;
property MessageB: TBytes read get_MessageB write set_MessageB;

Default Value

''

Remarks

This property contains the encoded message text or a path to a file that contains the encoded message text. The component fills out this property with the message body and MessageHeaders during encoding. The user may assign both the headers and the body to this property and leave MessageHeaders empty before decoding.

This property is not available at design time.

MessageHeaders Property (MIME Component)

This property includes the headers of the MIME message.

Syntax

property MessageHeaders: TipwHeaderList read get_MessageHeaders write set_MessageHeaders;

Remarks

This property contains the headers of the MIME message. The component fills out this property upon encoding. The user should use them as additional headers when emailing the Message.

During decoding, if this property is empty, the component will try to find the headers in the beginning of the Message and then will fill out this property accordingly.

Please refer to the Header type for a complete list of fields.

MessageHeadersString Property (MIME Component)

This property includes the string version of the MIME message headers.

Syntax

property MessageHeadersString: String read get_MessageHeadersString write set_MessageHeadersString;

Default Value

''

Remarks

The component fills out MessageHeadersString upon encoding. The user should use these strings as additional headers when emailing the Message.

This property contains a string version of the MIME message headers. During decoding, if this property is empty, the component will try to find the headers in the beginning of the Message and will fill out this property accordingly.

Parts Property (MIME Component)

This property contains information about all parts of a MIME message.

Syntax

property Parts: TipwMIMEPartList read get_Parts write set_Parts;

Remarks

This property contains information about all parts of a MIME message. A MIME message consists of different parts, separated by either a user-specified or an auto-generated boundary. Each part has its own set of headers that are contained in the Headers field.

The MIMEPARTS collection is filled out by the component when a call to either DecodeFromFile or DecodeFromString is made. However, when the EncodeToFile or EncodeToString methods are called, the component encodes the data given in either DecodedFile or DecodedString into a MIME message.

Please refer to the MIMEPart type for a complete list of fields.

Config Method (MIME Component)

Sets or retrieves a configuration setting.

Syntax

function Config(ConfigurationString: String): String;

Remarks

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

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, 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.

DecodeFromFile Method (MIME Component)

This method decodes from a file.

Syntax

procedure DecodeFromFile();

Remarks

This method decodes the data file given in Message and optionally MessageHeaders and fills out the Parts properties for each decoded part.

Example. Decoding from a File:

MIMEControl.Message = "C:\filename.txt" MIMEControl.DecodeFromFile

In this example, C:\filename.txt must contain the MIME headers and body. If not, the MessageHeaders property must be set to the appropriate MIME headers.

DecodeFromStream Method (MIME Component)

This method decodes from a stream.

Syntax

procedure DecodeFromStream(InputStream: TStream);

Remarks

This method decodes from a stream. It is the same as DecodeFromString, but now the MIME message is passed to this method as a stream.

This method decodes the data given by the InputStream and optionally MessageHeaders and fills out the Parts properties.

Example. Decoding a Mail Message:

MIMEControl.MessageHeaders.AddRange(MailControl.MessageHeaders) MIMEControl.DecodeFromStream(InputStream)

DecodeFromString Method (MIME Component)

This method decodes from a string.

Syntax

procedure DecodeFromString();

Remarks

This method decodes from a string. It is the same as DecodeFromFile, but now the Message denotes the real encoded message rather than a filename.

This method decodes the data given in Message and optionally MessageHeaders and fills out the Parts properties.

Example. Decoding a Mail Message:

MIMEControl.MessageHeadersString = MailControl.MessageHeaders MIMEControl.Message = MailControl.MessageText MIMEControl.DecodeFromString

DecodePart Method (MIME Component)

This method decodes the specified part.

Syntax

function DecodePart(index: Integer): TBytes;

Remarks

This method decodes the part specified by Index and returns the decoded part data.

DecodeFromString or DecodeFromFile must be called before calling this method. Calling this method will return the decoded bytes, and in addition, the DecodedString property will be populated with the string representation of the decoded data.

Example. Decoding a Specified Part:mime.MessageHeadersString = myMessageHeaders; mime.Message = myMessageBody; mime.DecodeFromString(); byte[] myPartContent = await mime.DecodePart(0);

DecodePartToFile Method (MIME Component)

This method decodes the specified part to a file on disk.

Syntax

function DecodePartToFile(index: Integer): String;

Remarks

This method decodes the part specified by Index to a temporary file. The full path to the temporary file is returned by this method. The user is responsible for deleting the temporary file.

DecodeFromString or DecodeFromFile must be called before calling this method.

EncodeToFile Method (MIME Component)

This method encodes to a file.

Syntax

procedure EncodeToFile();

Remarks

This method encodes the data given in Parts properties (either a decoded file or a decoded string) into a MIME message at Message and MessageHeaders using the values optionally given in Parts properties. To encode several objects into a MIME envelope, the user should first clear any old values left in the Parts properties.

The component will check for each item in Parts properties (first the decoded file and then the decoded string) for the data to encode.

The encoded message will be saved in the file pointed to by Message; the message headers will be held by MessageHeaders.

Example. Encoding Data:

MIMEControl.ResetData() MIMEControl.PartCount = 2 MIMEControl.PartDecodedString(0) = "This is plain text data" MIMEControl.PartEncoding(0) = peQuotedPrintable MIMEControl.PartContentType(0) = "text/plain" MIMEControl.PartDecodedFile(1) = "C:\filename.txt" MIMEControl.Message = "temp.tmp" MIMEControl.EncodeToFile()

EncodeToStream Method (MIME Component)

This method encodes to a stream.

Syntax

procedure EncodeToStream(OutputStream: TStream);

Remarks

This method encodes to a stream. It is the same as EncodeToString, but the encoded data are written to a stream instead of to the Message property.

This method encodes the data given in Parts collection into a MIME message. The Message gets written to the specified OutputStream and MessageHeaders using the values optionally given in the Parts collection. To encode several objects into a MIME envelope, the user should first clear any old values left in the Parts collection by calling ResetData.

The component will check each item in the Parts collection (first the decoded file and then the decoded string) for the data to encode.

The encoded message will be written to the specified OutputStream, and the message headers will be held by MessageHeaders.

Example. Encoding Data:

MIMEControl.ResetData() MIMEControl.Parts.Add(new MIMEPart()) MIMEControl.Parts.Add(new MIMEPart()) MIMEControl.Parts[0].DecodedString = "This is plain text data" MIMEControl.Parts[0].Encoding = peQuotedPrintable MIMEControl.Parts[0].ContentType = "text/plain" MIMEControl.Parts[1].DecodedFile = "C:\filename.txt" MIMEControl.EncodeToStream(OutputStream)

EncodeToString Method (MIME Component)

This method encodes to a string.

Syntax

procedure EncodeToString();

Remarks

This method encodes to a string. It is the same as EncodeToFile but the encoded data are held in the Message property rather than saved to a file.

This method encodes the data given in the Parts properties into a MIME message. The message gets stored in Message and MessageHeaders using the values optionally given in Parts properties. To encode several objects into a MIME envelope, the user should first clear any old values left in the Parts properties by calling ResetData.

The component will check each item in the Parts properties (first the decoded file and then the decoded string) for the data to encode.

The encoded message will be stored in the Message property; the message headers will be held by MessageHeaders.

Example. Encoding Data:

MIMEControl.ResetData() MIMEControl.PartCount = 2 MIMEControl.PartDecodedString(0) = "This is plain text data" MIMEControl.PartEncoding(0) = peQuotedPrintable MIMEControl.PartContentType(0) = "text/plain" MIMEControl.PartDecodedFile(1) = "C:\filename.txt" MIMEControl.EncodeToString()

Reset Method (MIME Component)

Reset the component.

Syntax

procedure Reset();

Remarks

This method will reset the component's properties to their default values.

ResetData Method (MIME Component)

This method resets the values of all headers and part properties.

Syntax

procedure ResetData();

Remarks

This method resets the values of all headers and part properties. It is an easy way to reset the component's properties before starting to populate the part properties with new values.

Error Event (MIME Component)

Fired when information is available about errors during data delivery.

Syntax

type TErrorEvent = procedure (
  Sender: TObject;
  ErrorCode: Integer;
  const Description: String
) of Object;

property OnError: TErrorEvent read FOnError write FOnError;

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the component raises an exception.

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.

Header Event (MIME Component)

This event is fired every time a header is parsed.

Syntax

type THeaderEvent = procedure (
  Sender: TObject;
  PartIndex: Integer;
  const Field: String;
  Value: String;
  ValueB: TBytes
) of Object;

property OnHeader: THeaderEvent read FOnHeader write FOnHeader;

Remarks

The PartIndex parameter contains the index of the part containing the current header. If the header is from the MIME body, this value will be -1. The Field parameter contains the name of the MIME header. The Value parameter contains the header contents. The Header event is fired when a header is parsed, which occurs for each header of the message when DecodeFromFile, DecodeFromString, or DecodeFromStream is called.

Progress Event (MIME Component)

This event shows the progress of decoding or encoding the input data.

Syntax

type TProgressEvent = procedure (
  Sender: TObject;
  PercentDone: Integer
) of Object;

property OnProgress: TProgressEvent read FOnProgress write FOnProgress;

Remarks

The Progress allows the user to visualize the progress of processing the input data.

The PercentDone parameter shows what percentage of the input has been read.

Header Type

This is an HTTP header as it is received from the server.

Remarks

When a header is received through a Header event, it is parsed into a Header type. This type contains a Field, and its corresponding Value.

Fields

Constructors

constructor Create();

constructor Create(valField: String; valValue: String);

MIMEPart Type

This is a part of the MIME message.

Remarks

Each MIME message is split into parts. A message must have at least one part to be a valid MIME message. The message itself is split into the MessageHeaders and the Message body. The body is then split into MIME parts by a specified or generated Boundary. Each part of a MIME message has its own Headers as well. These headers describe the MIMEPart and its contents.

The decoded data will be held in DecodedString or otherwise will be saved in a temporary file given by DecodedFile when the user asks for the value of the respective field.

If the encoded data are file data, the decoded file(s) will be given in the DecodedFile field. Otherwise, the decoded data will be in the DecodedString field.

When the EncodeToString method is called, the component will check for each item in the Parts properties (first the DecodedFile and then the DecodedString) for the data to encode.

Fields

Constructors

constructor Create();

constructor Create(valDecodedFile: String);

constructor Create(valDecodedString: TBytes);

Config Settings (MIME Component)

The component 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 component, access to these internal properties is provided through the Config method.

MIME Config Settings

Base Config Settings

Trappable Errors (MIME Component)

MIME Errors

	3   Can't create the file for write (illegal name or disk is write-protected).
	4   Can't open the file for read (doesn't exist?).
	5   Can't read from file.
	6   Can't write to file (disk full?).
	280   Invalid Part Index.
	281   Unknown MIME type.
	282   No MIME-boundary found.
	283   No file given.
	284   The component is busy.
	285   Can't create a temporary file to decode the data.
	286   Can't read Message file.
	287   No header separator found.
	289   No separator found.
	290   Input stream must have seeking enabled.