Pascal (Lazarus/Delphi)

Paging User Photos with Cursor

See more Facebook Examples

Demonstrates how to iterate over the pages of user photos using a cursor. 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.OAuth2,
  Chilkat.Rest,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  oauth2: TOAuth2;
  rest: TRest;
  responseJson: string;
  json: TJsonObject;
  afterCursor: string;

begin
  success := False;

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

  //  This example assumes a previously obtained an access token
  oauth2 := TOAuth2.Create;
  oauth2.AccessToken := 'FACEBOOK-ACCESS-TOKEN';

  rest := TRest.Create;

  //  Connect to Facebook.
  success := rest.Connect('graph.facebook.com',443,True,True);
  if (success <> True) then
    begin
      WriteLn(rest.LastErrorText);
      Exit;
    end;

  //  Provide the authentication credentials (i.e. the access key)
  rest.SetAuthOAuth2(oauth2);

  //  Indicate that we only want the photos the user has personally uploaded.
  rest.AddQueryParam('type','uploaded');

  //  We could limit the number of photos per page using the "limit" field.
  rest.AddQueryParam('limit','20');

  //  Get the 1st page of photos. (Not the actual image data, but the information about each photo.)
  //  See https://developers.facebook.com/docs/graph-api/reference/user/photos/ for more information.
  responseJson := rest.FullRequestNoBody('GET','/v2.7/me/photos');
  if (rest.LastMethodSuccess <> True) then
    begin
      WriteLn(rest.LastErrorText);
      Exit;
    end;

  json := TJsonObject.Create;
  json.EmitCompact := False;
  json.Load(responseJson);
  WriteLn(json.Emit());

  //  See Parsing the Facebook User Photos for code showing how to parse the JSON photos content.
  //  

  //  Get the "after" cursor.
  afterCursor := json.StringOf('paging.cursors.after');
  while json.LastMethodSuccess = True do
    begin

      WriteLn('after cursor: ' + afterCursor);

      //  Prepare for getting the next page of photos.
      //  We can continue using the same REST object.
      //  If already connected, we'll continue using the existing connection.
      //  Otherwise, a new connection will automatically be made if needed.
      rest.ClearAllQueryParams();
      rest.AddQueryParam('type','uploaded');
      rest.AddQueryParam('limit','20');
      rest.AddQueryParam('after',afterCursor);

      responseJson := rest.FullRequestNoBody('GET','/v2.7/me/photos');
      if (rest.LastMethodSuccess <> True) then
        begin
          WriteLn(rest.LastErrorText);
          Exit;
        end;

      json.Load(responseJson);
      //  See Parsing the Facebook User Photos for code showing how to parse the JSON photos content.

      WriteLn(json.Emit());

      //  Get the cursor for the next page.
      afterCursor := json.StringOf('paging.cursors.after');
    end;

  WriteLn('No more pages of photos.');


  oauth2.Free;
  rest.Free;
  json.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.