getAccessToken method

Future<String?> getAccessToken()

Retrieves an access token from Azure AD using the client credentials flow.

This function:

1. Sends a POST request to Azure Active Directory (AAD) token endpoint using the provided tenantId, clientId, clientSecret, and resource.
2. If the request is successful (HTTP 200), it returns the access_token.
3. If the request fails, it logs the error message and returns null.

Returns:

• A String containing the access token if successful.
• null if the request fails.

Implementation

Future<String?> getAccessToken() async {
  final url = Uri.parse(
    'https://login.microsoftonline.com/$tenantId/oauth2/token',
  );

  final response = await http.post(
    url,
    body: {
      'grant_type': 'client_credentials',
      'client_id': clientId,
      'client_secret': clientSecret,
      'resource': resource,
    },
  );

  if (response.statusCode == 200) {
    return json.decode(response.body)['access_token'];
  } else {
    print("❌ Failed to get token: ${response.body}");
    return null;
  }
}