Pascal (Lazarus/Delphi)

Download GMail Message Attachment by ID

See more GMail REST API Examples

Demonstrates how to download a GMail email attachment by the attachment ID. 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.Http,
  Chilkat.StringBuilder,
  Chilkat.BinData,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  http: THttp;
  attachmentId: string;
  messageId: string;
  url: string;
  outputFilePath: string;
  sbJson: TStringBuilder;
  json: TJsonObject;
  bd: TBinData;

begin
  success := False;

  //  This example requires the Chilkat API to have been previously unlocked.
  //  See Global Unlock Sample for sample code.

  http := THttp.Create;

  http.AuthToken := 'ACCESS_TOKEN';
  http.Accept := 'application/json';

  //  See the following example:  Get GMail Message (format=full)
  //  It shows how to download an email by message ID, and it shows how to parse the JSON
  //  response which includes attachment names, ids, and other information.

  //  This example will assume we already have the attachment id and filename.

  //  This is the attachment ID for a file named "helloWorld.pdf".
  attachmentId := 'ANGjdJ-oy3aCuZISJKLAhUdaEksCEklbAPyMaWzFgqOMGbPCRkgwgeu_Kttd99C17OBTHROkDZGekibTKWXGfscB5ww7fw4E65_V1dQ-jHhb2TD1Cdm58-BbNw2iDxzptco8iILPiSnLLfFn5Ps7nsRcxHaGTt3r0yqFKCuIYNnPK1vM04BXI_cfzo-HnI4I3tD6oHNHOGVQrL01MdShFQjPELPUjXM8z1qs7Kom-QyvV1iOldUN-66UuhynsmDX-CMM5TIdB-8KD_lmdhf-0DqG8JnCA20XpXyfqwS8XFkPA-t-QSjb7SdkHQFtQ4lz2PcBREFzZ2eI5j0l0Y_dQHRPYTeMwkVl1yl4MfFT4C4iso3VSF-eqaIjiFCbXKCFNyeEIW5WFsv189dhlSqU';

  messageId := '1712bc1dc22da2a2';

  http.SetUrlVar('messageId',messageId);
  http.SetUrlVar('attachmentId',attachmentId);

  url := 'https://www.googleapis.com/gmail/v1/users/userId/messages/{$messageId}/attachments/{$attachmentId}';

  //  When we download, the response is JSON that contains the attachment data base64url encoded, like this:
  //  {
  //   "size": 934,
  //   "data": "JVBERi0xLjM ... CiUlRU9GCg=="
  //  }

  outputFilePath := 'qa_output/helloWorld.pdf';

  //  Download into a StringBuilder.
  sbJson := TStringBuilder.Create;
  success := http.DownloadSb(url,'utf-8',sbJson);
  if (success = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  if (http.LastStatus <> 200) then
    begin
      //  Something failed.
      //  the JSON contains an error message.
      WriteLn(sbJson.GetAsString());
      Exit;
    end;

  //  Load into a Chilkat JSON object.
  json := TJsonObject.Create;
  success := json.LoadSb(sbJson);

  //  Extract the base64url data into a BinData.
  bd := TBinData.Create;
  success := json.BytesOf('data','base64url',bd);

  //  Save the data to a file.
  success := bd.WriteFile('qa_output/helloWorld.pdf');

  WriteLn('Success.');


  http.Free;
  sbJson.Free;
  json.Free;
  bd.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.