Dart Requires Chilkat v11.0.0+

Lower-Level REST API Methods (Google Cloud Storage)

See more REST Examples

The FullRequest* methods, such as FullRequestBinary, FullRequestMultipart, FullRequestNoBody, FullRequestStream, FullRequestString, etc. are high-level REST API methods that both send the request and receive the response. It is often the case that an application needs make a REST call, but with a finer level of control. The Chilkat REST API provides this feature. An application can break a REST call into the following parts:

1. Send the HTTP request. (via the SendReq* methods)
2. Receive the HTTP response header. (ReadResponseHeader)
3. Receive the HTTP response body. (via the ReadRespBody* methods)

This example demonstrates a REST call using SendReqStringBody, ReadResonseHeader, and ReadRespBodyString.

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example demonstrates a REST call using SendReqStringBody, ReadResonseHeader, and ReadRespBodyString.
  // It will create a bucket in Google Cloud Storage.

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

  final gAuth = CkAuthGoogle();
  // Obtain an access token as shown in one of the following examples:
  // See Get Access Token using a Service Account JSON Key
  // See Get Access Token using a P12 File

  final rest = CkRest();

  // Connect using TLS.
  final bAutoReconnect = true;
  rest.connect('www.googleapis.com', 443, true, bAutoReconnect);

  // Provide the authentication credentials (i.e. the access key)
  rest.setAuthGoogle(gAuth);

  // Build the JSON request body for creating a bucket.
  // The only required property is the "name", but we'll add more
  // to make a better example..
  final jsonReqBody = CkJsonObject();
  jsonReqBody.addStringAt(-1, 'name', 'chilkat-bucket-c');
  jsonReqBody.addStringAt(-1, 'kind', 'storage#bucket');
  jsonReqBody.addStringAt(-1, 'location', 'US');

  final objVersioning = CkJsonObject();
  jsonReqBody.appendObject2('versioning', objVersioning);
  objVersioning.addBoolAt(-1, 'enabled', true);

  // Show the HTTP request body we'll be sending.
  print(jsonReqBody.emit());

  // Add the required query parameter.
  // See https://cloud.google.com/storage/docs/json_api/v1/buckets/insert
  rest.addQueryParam('project', 'chilkattest-1050');

  // Add the Content-Type HTTP request header.
  rest.addHeader('Content-Type', 'application/json; charset=UTF-8');

  // Send the REST HTTP request.
  try {
    rest.sendReqStringBody('POST', '/storage/v1/b', jsonReqBody.emit());
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Read the response header.
  final responseStatusCode = rest.readResponseHeader();
  if (responseStatusCode < 0) {
    // We were unable to receive the response header.
    print(rest.lastErrorText);
    return;
  }

  if (responseStatusCode != 200) {
    // The response was not successful.  We'll still need to receive 
    // the response body, which may contain an error message from the server.
    // If the response has no body, then the method for reading the
    // response body can still be called.  It will simply return with an empty
    // response body.

    // We can examine the response header and status text:
    print('Response status text: ${rest.responseStatusText}');
    print('Response header: ${rest.responseHeader}');
  }

  // Read the response body.  In this case we're expecting it to be JSON..
  final String responseBodyStr;
  try {
    responseBodyStr = rest.readRespBodyString();
  } on ChilkatException catch (e) {
    // We were unable to receive the response body.
    // Note: If the response did not include a body (such as for cases where
    // the Content-Length header is 0, or if the response status code implicitly
    // indicates no body, then ReadRespBodyString returns cktrue, and the
    // responseBodyString will be an empty string.
    print(e.lastErrorText);
    return;
  }

  // Show the JSON response.
  print('Json Response: $responseBodyStr');
}