Pascal (Lazarus/Delphi)

Manage Cloud Storage Bucket Labels

See more Google Cloud Storage Examples

Demonstrates how to add, update, and delete labels for a Cloud Storage bucket. 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;
  sbToken: TStringBuilder;
  json: TJsonObject;
  http: THttp;
  url: string;
  resp: THttpResponse;
  responseCode: Integer;

begin
  success := False;

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

  //  This example uses a previously obtained access token having permission for the 
  //  scope "https://www.googleapis.com/auth/cloud-platform"

  //  In this example, Get Google Cloud Storage OAuth2 Access Token, 
  //  the service account access token was saved to a text file.  This example fetches the access token from the file..
  sbToken := TStringBuilder.Create;
  sbToken.LoadFile('qa_data/tokens/googleCloudStorageAccessToken.txt','utf-8');

  //  ---- Step 1
  //  Create the JSON body of the PATCH request that will be sent.
  //  This specifies labels to be added, updated, and/or deleted.
  //  (To delete a label, set its value equal to null.)

  //  {
  //    "labels": {
  //      "new_label_key": "new_label_value",
  //      "existing_label_key": "updated_label_value",
  //      "old_label_key": null
  //    }
  //  }

  //  ---------
  //  Important
  //  ---------
  //  You can apply multiple labels to each bucket, with a maximum of 64 labels per bucket.

  //      - Keys and values cannot be longer than 63 characters each.
  //      - Keys and values can only contain lowercase letters, numeric characters, underscores, and dashes. International characters are allowed.
  //      - Label keys must start with a lowercase letter and international characters are allowed.
  //      - Label keys cannot be empty.

  //  Build JSON to update labels.
  //  
  //  During the testing of this example, my bucket already has the following labels:
  //  {
  //   "labels": {
  //    "test1": "xyz",
  //    "test": "abc",
  //    "a": "abc"
  //   }
  //  }

  //  For this example, I'm going to add a label "b", delete the label "test1", and update
  //  the label "test".
  json := TJsonObject.Create;
  json.UpdateString('labels.b','bbb');
  json.UpdateString('labels.test','abc123');
  json.UpdateNull('labels.test1');

  //  ---- Step 2
  //  Send a PATCH equivalent to this curl command

  //  curl -X PATCH --data-binary @[JSON_FILE_NAME].json \
  //      -H "Authorization: Bearer [OAUTH2_TOKEN]" \
  //      -H "Content-Type: application/json" \
  //      "https://www.googleapis.com/storage/v1/b/[BUCKET_NAME]?fields=labels"

  http := THttp.Create;
  http.AuthToken := sbToken.GetAsString();

  http.SetUrlVar('bucket_name','chilkat-ocean');
  url := 'https://www.googleapis.com/storage/v1/b/{$bucket_name}?fields=labels';
  resp := THttpResponse.Create;
  success := http.HttpJson('PATCH',url,json,'application/json',resp);
  if (success = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  responseCode := resp.StatusCode;
  if (responseCode = 401) then
    begin
      WriteLn(resp.BodyStr);
      WriteLn('If invalid credentials, then it is likely the access token expired.');
      WriteLn('Your app should automatically fetch a new access token and re-try.');
      Exit;
    end;

  //  Note: A 400 response code is likely caused by illegal characters used for a label name and/or value.

  WriteLn('Response code: ' + responseCode);
  WriteLn('Response body');
  WriteLn(resp.BodyStr);

  //  A response code = 200 indicates success, and the response body contains the JSON
  //  for the new/updated set of labels
  //  Response code: 200
  //  Response body
  //  {
  //   "labels": {
  //    "test": "abc123",
  //    "a": "abc",
  //    "b": "bbb"
  //   }
  //  }


  sbToken.Free;
  json.Free;
  http.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.