(Delphi ActiveX) Download GMail Message Attachment by ID

Demonstrates how to download a GMail email attachment by the attachment ID.

For more information, see https://developers.google.com/gmail/api/v1/reference/users/messages/attachments/get

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
http: TChilkatHttp;
success: Integer;
attachmentId: WideString;
messageId: WideString;
url: WideString;
outputFilePath: WideString;
sbJson: TChilkatStringBuilder;
json: TChilkatJsonObject;
bd: TChilkatBinData;

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

http := TChilkatHttp.Create(Self);

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 := TChilkatStringBuilder.Create(Self);
success := http.DownloadSb(url,'utf-8',sbJson.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(http.LastErrorText);
    Exit;
  end;

if (http.LastStatus <> 200) then
  begin
    // Something failed.
    // the JSON contains an error message.
    Memo1.Lines.Add(sbJson.GetAsString());
    Exit;
  end;

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

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

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

Memo1.Lines.Add('Success.');
end;