Pascal (Lazarus/Delphi)

Google Drive - Resumable Upload

See more Google Drive Examples

Demonstrates how to do a resumable upload to Google Drive. 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.Url,
  Chilkat.HttpResponse,
  Chilkat.HttpRequest,
  Chilkat.JsonObject,
  Chilkat.StringBuilder,
  Chilkat.Http;

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

procedure RunDemo;
var
  success: Boolean;
  http: THttp;
  json: TJsonObject;
  resp: THttpResponse;
  statusCode: Integer;
  sbSessionUri: TStringBuilder;
  sessionUri: string;
  req: THttpRequest;
  url: TUrl;

begin
  success := False;

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

  success := True;

  //  This example uses a previously obtained access token having permission for the 
  //  Google Drive scope. 
  //  See Get Google Drive OAuth2 Access Token

  http := THttp.Create;

  http.AuthToken := 'GOOGLE_DRIVE_ACCESS_TOKEN';

  //  First we want to initiate the resumable upload.
  //  We send a POST to get a session URI, which will be used to upload the file, and resume if needed.

  //  Our POST will look like this:

  //  POST https://www.googleapis.com/upload/drive/v3/files?uploadType=resumable HTTP/1.1
  //  Authorization: Bearer [YOUR_AUTH_TOKEN]          <-- Chilkat automatically adds this header because the AuthToken property was set.
  //  Content-Length: 38                               <-- Chilkat will automatically add this header.
  //  Content-Type: application/json; charset=UTF-8    <-- This is the type of this POST, and is specified in the call to HttpJson.
  //  X-Upload-Content-Type: application/zip           <-- The type of file we'll be uploading
  //  X-Upload-Content-Length: 1366807                 <-- The size of the file we'll be uploading
  //  
  //  {
  //    "name": "myObject"
  //  }

  http.SetRequestHeader('X-Upload-Content-Type','application/zip');
  http.SetRequestHeader('X-Upload-Content-Length','1366807');

  json := TJsonObject.Create;
  json.UpdateString('name','myZip');

  resp := THttpResponse.Create;
  success := http.HttpJson('POST','https://www.googleapis.com/upload/drive/v3/files?uploadType=resumable',json,'application/json',resp);
  if (success = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  statusCode := resp.StatusCode;
  if (statusCode <> 200) then
    begin
      WriteLn(resp.BodyStr);
      WriteLn('response status = ' + statusCode);
      Exit;
    end;

  //  The session URI is in the "Location" response header:
  sbSessionUri := TStringBuilder.Create;
  sbSessionUri.Append(resp.GetHeaderField('Location'));
  sessionUri := sbSessionUri.GetAsString();
  WriteLn('Session URI: ' + sessionUri);

  //  Here's a sample session URI:  https://www.googleapis.com/upload/drive/v3/files?uploadType=resumable&upload_id=AEnB2UrszR8lDqlo3mtXJw_0rYI_Hi1oVh1NPFcLfoyBq9NcSjk85kFopoZaVEgT38OSmLl0XsObPf4iCSJwHlrOvvIJQ_ckIQ

  //  -----------------------------------------------------------------------------
  //  The next step is to upload the file using the session URI:

  //  We'll send a PUT that looks like this:

  //  PUT https://www.googleapis.com/upload/drive/v3/files?uploadType=resumable&upload_id=xa298sd_sdlkj2 HTTP/1.1
  //  Content-Length: 1366807
  //  Content-Type: application/zip
  //  
  //  [BYTES 0-1366806]

  //  First remove the X-Upload-Content-Type and X-Upload-Content-Length request headers we specified earlier, so they don't get sent with subsequent requests.
  http.ClearHeaders();

  //  Because the file is likely large, we'll use HttpSReq which allows to to pass an HTTP request object where the body can be streamed directly from a file.
  req := THttpRequest.Create;

  req.ContentType := 'application/zip';
  req.HttpVerb := 'PUT';

  url := TUrl.Create;
  url.ParseUrl(sessionUri);

  req.Path := url.PathWithQueryParams;
  WriteLn('Path with Query Param: ' + url.PathWithQueryParams);

  //  Specify that the request body is to be streamed directly from a file.
  success := req.StreamBodyFromFile('qa_data/zips/big.zip');
  if (success = False) then
    begin
      WriteLn(req.LastErrorText);
      Exit;
    end;

  success := http.HttpSReq(url.Host,url.Port,url.Ssl,req,resp);
  if (success = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

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

  //  Sample output:

  //  {
  //   "kind": "drive#file",
  //   "id": "1rx20i53eurtkVQ-RT7Ry8Ct85PgPYMET",
  //   "name": "myZip",
  //   "mimeType": "application/zip"
  //  }
  //  
  //  response status = 200


  http.Free;
  json.Free;
  resp.Free;
  sbSessionUri.Free;
  req.Free;
  url.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.