Delphi DLL

Download GMail Message Attachment by ID

See more GMail REST API Examples

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

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Http, StringBuilder, BinData, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
http: HCkHttp;
attachmentId: PWideChar;
messageId: PWideChar;
url: PWideChar;
outputFilePath: PWideChar;
sbJson: HCkStringBuilder;
json: HCkJsonObject;
bd: HCkBinData;

begin
success := False;

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

http := CkHttp_Create();

CkHttp_putAuthToken(http,'ACCESS_TOKEN');
CkHttp_putAccept(http,'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';

CkHttp_SetUrlVar(http,'messageId',messageId);
CkHttp_SetUrlVar(http,'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 := CkStringBuilder_Create();
success := CkHttp_DownloadSb(http,url,'utf-8',sbJson);
if (success = False) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

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

// Load into a Chilkat JSON object.
json := CkJsonObject_Create();
success := CkJsonObject_LoadSb(json,sbJson);

// Extract the base64url data into a BinData.
bd := CkBinData_Create();
success := CkJsonObject_BytesOf(json,'data','base64url',bd);

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

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

CkHttp_Dispose(http);
CkStringBuilder_Dispose(sbJson);
CkJsonObject_Dispose(json);
CkBinData_Dispose(bd);

end;