Pascal (Lazarus/Delphi)

Get GMail Message Metadata

See more GMail REST API Examples

Demonstrates how to get the metadata for each message in a list of message IDs. 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.HttpResponse,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  http: THttp;
  jsonMsgIds: TJsonObject;
  resp: THttpResponse;
  id: string;
  i: Integer;
  count_i: Integer;
  jsonResponse: TJsonObject;

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';

  //  Let's say we have the following JSON containing a list of message ID's

  //  {
  //    "messages": [
  //      {
  //        "id": "1712bc1dc22da2a2",
  //        "threadId": "1712bc1dc22da2a2"
  //      },
  //      {
  //        "id": "1712b94fa2168040",
  //        "threadId": "1712b94fa2168040"
  //      },
  //      {
  //        "id": "1711e4bd96ded05e",
  //        "threadId": "1711e4bd96ded05e"
  //      },
  //      {
  //        "id": "1711de0d119e751e",
  //        "threadId": "1711de0d119e751e"
  //      },
  //      {
  //        "id": "1711c81a43050f59",
  //        "threadId": "1711c81a43050f59"
  //      },
  //      {
  //        "id": "1711c2c1516abce5",
  //        "threadId": "1711c2c1516abce5"
  //      },
  //      {
  //        "id": "1711c161e655c915",
  //        "threadId": "1711c161e655c915"
  //      },
  //      {
  //        "id": "171199c6e454558c",
  //        "threadId": "171199c6e454558c"
  //      },
  //      {
  //        "id": "17119474c8aa248e",
  //        "threadId": "17119474c8aa248e"
  //      }
  //    ],
  //    "nextPageToken": "16710921492249671162",
  //    "resultSizeEstimate": 309
  //  }

  //  Normally your program would have the above JSON in a string variable (obtained from a previous call to get
  //  a list of message IDs from a GMail mailbox).  In this example, we'll load the JSON from a file.
  jsonMsgIds := TJsonObject.Create;
  success := jsonMsgIds.LoadFile('qa_data/json/gmail_message_ids.json');

  resp := THttpResponse.Create;

  i := 0;
  count_i := jsonMsgIds.SizeOfArray('messages');
  while i < count_i do
    begin
      jsonMsgIds.I := i;
      id := jsonMsgIds.StringOf('messages[i].id');

      //  Get the metadata for this message ID.
      http.SetUrlVar('id',id);

      success := http.HttpNoBody('GET','https://www.googleapis.com/gmail/v1/users/userId/messages/{$id}?format=metadata',resp);
      if (success = False) then
        begin
          WriteLn(http.LastErrorText);
          Exit;
        end;

      WriteLn('Response Status Code: ' + resp.StatusCode);

      jsonResponse := TJsonObject.Create;
      jsonResponse.Load(resp.BodyStr);
      jsonResponse.EmitCompact := False;
      WriteLn(jsonResponse.Emit());

      if (resp.StatusCode <> 200) then
        begin
          WriteLn('Failed.');
          Exit;
        end;

      i := i + 1;
    end;

  //  Use this online tool to generate parsing code from sample JSON: 
  //  Generate Parsing Code from JSON


  http.Free;
  jsonMsgIds.Free;
  resp.Free;
      jsonResponse.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.