Pascal (Lazarus/Delphi)

BatchModify - Add a Label to each Message in Search Results

See more GMail REST API Examples

Searchs GMail for messages meeting a criteria and adds a label to each message found. 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.HttpResponse,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  http: THttp;
  userId: string;
  query: string;
  url: string;
  sb: TStringBuilder;
  json: TJsonObject;
  json2: TJsonObject;
  i: Integer;
  numMessages: Integer;
  id: string;
  labelId: string;
  resp: THttpResponse;

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 := 'GMAIL-ACCESS-TOKEN';

  userId := 'me';
  http.SetUrlVar('userId',userId);

  query := 'subject:questions';
  http.SetUrlVar('query',query);

  url := 'https://www.googleapis.com/gmail/v1/users/{$userId}/messages?q={$query}';

  sb := TStringBuilder.Create;
  success := http.QuickGetSb(url,sb);
  if (success = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  json := TJsonObject.Create;
  json.LoadSb(sb);
  json.EmitCompact := False;
  WriteLn(json.Emit());

  if (http.LastStatus <> 200) then
    begin
      WriteLn('Failed.');
      Exit;
    end;

  //  If successful, the received JSON looks like this:
  //  {
  //    "messages": [
  //      {
  //        "id": "166f583051d36144",
  //        "threadId": "166f583051d36144"
  //      },
  //      {
  //        "id": "166f5815e1f36144",
  //        "threadId": "166f5815e1f36144"
  //      },
  //  	...
  //      {
  //        "id": "166f580639e36144",
  //        "threadId": "166f580639e36144"
  //      },
  //      {
  //        "id": "15dbc2e28ec789c6",
  //        "threadId": "15dbc2e28ec789c6"
  //      }
  //    ],
  //    "nextPageToken": "13434766102274844688",
  //    "resultSizeEstimate": 103
  //  }
  //  

  //  Next, we'll be sending an HTTP POST to add the label "questions" to each message in the
  //  search results.  The JSON to be sent for the batchModify is this:

  //  	{
  //  	  "ids": [
  //  	    string
  //  	  ],
  //  	  "addLabelIds": [
  //  	    string
  //  	  ],
  //  	  "removeLabelIds": [
  //  	    string
  //  	  ]
  //  	}

  //  We'll omit "removeLabelIds" because we're not removing any labels.
  //  We are parsing the JSON search results, and at the same time building the batchModify JSON.

  json2 := TJsonObject.Create;

  i := 0;
  numMessages := json.SizeOfArray('messages');
  while (i < numMessages) do
    begin
      json.I := i;
      id := json.StringOf('messages[i].id');
      json2.I := i;
      json2.UpdateString('ids[i]',id);
      i := i + 1;
    end;

  //  We need the id of the label (not the name).
  //  I know the name of the label is "questions", but I need to know the id.
  //  See this example: Get Label Id by Name
  //  The id of my label named "questions" is "Label_43"
  labelId := 'Label_43';
  json2.UpdateString('addLabelIds[0]',labelId);
  json2.UpdateNewArray('removeLabelIds');

  json2.EmitCompact := False;
  WriteLn(json2.Emit());

  //  Send the batchModify
  url := 'https://www.googleapis.com/gmail/v1/users/{$userId}/messages/batchModify';
  resp := THttpResponse.Create;
  success := http.HttpJson('POST',url,json2,'application/json',resp);
  if (success = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  WriteLn('status = ' + resp.StatusCode);

  //  A 204 response status indicate success.
  if (resp.StatusCode <> 204) then
    begin
      WriteLn(resp.BodyStr);
      WriteLn('Failed.');
      Exit;
    end;

  //  The 204 response has an empty response body..

  WriteLn('BatchModify success!');


  http.Free;
  sb.Free;
  json.Free;
  json2.Free;
  resp.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.