Pascal (Lazarus/Delphi)

The MIME Content-Type Header Field

See more MIME Examples

Explains the ContentType property and the Content-Type header field including the various attributes that may be included. Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Mime;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  mime: TMime;

begin
  success := False;

  //  Every part in a MIME messsage should include a Content-Type header field.
  //  The Content-Type indicates the type of content contained in the MIME part.
  //  For example: text/plain, image/jpeg, application/pdf, application/json, multipart/mixed, etc.

  //  Multipart content types are those where the MIME part's body is composed of N inner MIME messages,
  //  separated by a boundary string.
  //  This is how MIME gets a nested, tree-like structure.  The most common multipart MIME types
  //  are (for email related MIME) multipart/mixed, multipart/alternative, and multipart/related,
  //  and for HTTP related MIME, it is multipart/form-data.

  mime := TMime.Create;

  //  The Content-Type header field can be set or modified in two ways.
  //  1) By setting the ContentType, Micalg, Name, Charset, Boundary, or Protocol properties.
  //     Setting the ContentType property sets the primary value (such as "text/plain") of the header field.
  //     Each of the other properties listed above will replace or add a particular attribute value.

  //  2) By setting the entire contents of the ContentType header with the SetHeaderField method.
  //     This updates each of the Content-Type related properties.

  //  For example:
  mime.ContentType := 'text/plain';
  mime.Charset := 'utf-8';

  //  The Content-Type header field contains this:
  //      Content-Type: text/plain; charset=utf-8
  WriteLn(mime.GetEntireHead());
  WriteLn('-');

  mime.SetHeaderField('Content-Type','image/jpeg; name="kitty.jpg"');
  //  The Content-Type header field now contains this:
  //      Content-Type: image/jpeg; name="kitty.jpg"
  WriteLn(mime.GetEntireHead());
  WriteLn('-');

  //  Notice how the properties have been updated:
  WriteLn('ContentType property: ' + mime.ContentType);
  WriteLn('Charset property: ' + mime.Charset);
  WriteLn('Name property: ' + mime.Name);
  WriteLn('-');

  //  To change a particular attribute value, set the property.
  mime.Name := 'doggy.jpg';
  WriteLn(mime.GetEntireHead());
  WriteLn('-');

  //  To remove an attribute value from the Content-Type header,
  //  set the property to an empty string.
  mime.Name := '';
  WriteLn(mime.GetEntireHead());
  WriteLn('-');


  mime.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.