Dart

Azure Storage: CORS Preflight Blob Request

See more Azure Cloud Storage Examples

Azure Storage Blob Service REST API: Sample code to send a CORS pre-flight blob request. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // Azure Blob Service Example: CORS Preflight Blob Request
  // See also: https://msdn.microsoft.com/en-us/library/azure/dn535599.aspx

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

  final rest = CkRest();

  // Connect to the Azure Storage Blob Service
  final bTls = true;
  final port = 443;
  final bAutoReconnect = true;
  // In this example, the storage account name is "chilkat".
  try {
    rest.connect('chilkat.blob.core.windows.net', port, bTls, bAutoReconnect);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Provide Azure Cloud credentials for the REST call.
  final azAuth = CkAuthAzureStorage();
  azAuth.accessKey = 'AZURE_ACCESS_KEY';
  // The account name used here should match the 1st part of the domain passed in the call to Connect (above).
  azAuth.account = 'chilkat';
  azAuth.scheme = 'SharedKey';
  azAuth.service = 'Blob';
  // This causes the "x-ms-version: 2021-08-06" header to be automatically added.
  azAuth.xMsVersion = '2021-08-06';
  rest.setAuthAzureStorage(azAuth);

  // Note: The application does not need to explicitly set the following
  // headers: x-ms-date, Authorization.  These headers
  // are automatically set by Chilkat.

  // The preflight blob request requires the following two HTTP headers.
  // The Origin is the domain from which the actual request will be issued.
  rest.addHeader('Origin', 'www.contoso.com');
  // The Access-Control-Request-Method is the HTTP method (such as GET, POST, PUT, etc.) of the actual request.
  rest.addHeader('Access-Control-Request-Method', 'PUT');

  // The expected response is a 202 response status code with no response body.
  // The name of the container or blob resource in this example is "test". (Replace "test" with your container name.)
  final String responseStr;
  try {
    responseStr = rest.fullRequestNoBody('OPTIONS', '/test');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // When successful, the Azure Storage service will respond with a 200 response code,
  // with no response body.

  // If CORS is not enabled or no matching rule is found for the request, 
  // then a 403 status code is returned, with the following status text:
  // "CORS not enabled or no matching rule found for this request."
  if (rest.responseStatusCode != 200) {
    // Examine the request/response to see what happened.
    print('response status code = ${rest.responseStatusCode}');
    print('response status text = ${rest.responseStatusText}');
    print('response header: ${rest.responseHeader}');
    print('response body (if any): $responseStr');
    print('---');
    print('LastRequestStartLine: ${rest.lastRequestStartLine}');
    print('LastRequestHeader: ${rest.lastRequestHeader}');
    return;
  }

  print('Success: Preflight Blob Request is accepted.');
}