Pascal (Lazarus/Delphi)

Get a Header Attribute of a Related Item

Demonstrates the Chilkat Email.GetRelatedAttr method, which returns a header-field attribute value from a header field of the Nth related item. The first argument is the zero-based related-item index, the second names a header field, and the third names an attribute within it. This example loads an image from a file into a BinData object, adds it as a related item with AddRelatedBd (capturing the generated Content-ID and referencing it from the HTML), then reads the name attribute of the related item's Content-Type header.

Background: Related items (inline images, style sheets) are MIME parts whose headers may carry named parameters — for instance Content-Type: image/png; name="logo.png". Because an image is binary, it is loaded into a BinData object (here from a file) and added with AddRelatedBd, rather than being treated as text. GetRelatedAttr then extracts one named attribute from a chosen header of a specific related part, the related-item analogue of GetAttachmentAttr, so you don't have to parse the raw header yourself.

Chilkat Pascal (Lazarus/Delphi) Downloads

Download Chilkat for Pascal (Lazarus/Delphi)

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.BinData,
  Chilkat.StringBuilder,
  Chilkat.Email;

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

procedure RunDemo;
var
  success: Boolean;
  email: TEmail;
  bdImage: TBinData;
  cid: string;
  sbHtml: TStringBuilder;
  numReplaced: Integer;
  val: string;

begin
  success := False;

  //  Demonstrates the GetRelatedAttr method, which returns a header-field attribute value
  //  from a header field of the Nth related item.  The first argument is the zero-based related-item
  //  index, the second is the header field name, and the third is the attribute name.

  email := TEmail.Create;
  email.Subject := 'GetRelatedAttr example';

  //  Load the image data from a file into a BinData object.
  bdImage := TBinData.Create;
  success := bdImage.LoadFile('qa_data/images/logo.png');
  if (success = False) then
    begin
      WriteLn(bdImage.LastErrorText);
      Exit;
    end;

  //  Add the image as a related item from the BinData; capture its generated Content-ID.
  cid := email.AddRelatedBd('logo.png',bdImage);
  if (email.LastMethodSuccess = False) then
    begin
      WriteLn(email.LastErrorText);
      Exit;
    end;

  //  Reference the related item in the HTML body by its Content-ID.
  sbHtml := TStringBuilder.Create;
  sbHtml.Append('<html><body><img src="cid:PLACEHOLDER_CID"/></body></html>');
  numReplaced := sbHtml.Replace('PLACEHOLDER_CID',cid);
  email.SetHtmlBody(sbHtml.GetAsString());

  //  Get the "name" attribute of the related item's Content-Type header (index 0).
  val := email.GetRelatedAttr(0,'Content-Type','name');
  WriteLn('Related item Content-Type name attribute: ' + val);

  //  Note: The path "qa_data/images/logo.png" is a relative local filesystem path,
  //  relative to the current working directory of the running application.


  email.Free;
  bdImage.Free;
  sbHtml.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.