Dart

USPS OAuth2 Client Credentials

See more OAuth2 Examples

Get an OAuth2 access token for the United States Postal Service (USPS) REST API. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example assumes the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  final http = CkHttp();

  // Implements the following CURL command:

  // curl -X POST https://apis.usps.com/oauth2/v3/token \
  //   -H "Content-Type: application/x-www-form-urlencoded" \
  //   -d "grant_type=client_credentials" \
  //   -d "client_id=123456789" \
  //   -d "client_secret=A1B2C3D4E5" \
  //   -d "scope=ResourceA+ResourceB+ResourceC"

  // Use the following online tool to generate HTTP code from a CURL command
  // Convert a cURL Command to HTTP Source Code

  final req = CkHttpRequest();
  req.addParam('grant_type', 'client_credentials');
  req.addParam('client_id', '123456789');
  req.addParam('client_secret', 'A1B2C3D4E5');
  req.addParam('scope', 'ResourceA+ResourceB+ResourceC');

  req.httpVerb = 'POST';
  req.contentType = 'application/x-www-form-urlencoded';

  final resp = CkHttpResponse();
  try {
    http.httpReq('https://apis.usps.com/oauth2/v3/token', req, resp);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final sbResponseBody = CkStringBuilder();
  resp.getBodySb(sbResponseBody);

  final jResp = CkJsonObject();
  jResp.loadSb(sbResponseBody);
  jResp.emitCompact = false;

  print('Response Body:');
  print(jResp.emit());

  final respStatusCode = resp.statusCode;
  print('Response Status Code = $respStatusCode');
  if (respStatusCode >= 400) {
    print('Response Header:');
    print(resp.header);
    print('Failed.');
    return;
  }

  // Sample JSON response:
  // (Sample code for parsing the JSON response is shown below)

  // {
  //   "access_token": "eyJraWQiOiIxMDEwMTAiLCJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.eyJzdWIiOiIiLCJhdWQiOiJhZGRyZXNzZXMgaW50ZXJuYXRpb25hbC1wcmljZXMgc3Vic2NyaXB0aW9ucyBwYXltZW50cyBwaWNrdXAgdHJhY2tpbmcgbGFiZWxzIHNjYW4tZm9ybXMgY29tcGFuaWVzIHNlcnZpY2UtZGVsaXZlcnktc3RhbmRhcmRzIGxvY2F0aW9ucyBpbnRlcm5hdGlvbmFsLWxhYmVscyBwcmljZXMiLCJhenAiOiJoeXI3YjN2Q1J0cFl0QUhNMWE4Y2RVcmt5eUZtTmtiZyIsIm9yZ2FuaXphdGlvbl9pZCI6IjAiLCJpc3MiOiJ1cm46XC9cL2FwaS51c3BzLmNvbSIsImV4cCI6MTY4MDkxNzc4NiwiaWF0IjoxNjgwODg4OTg2LCJqdGkiOiI3YjU5MzJlMS05NjIxLTQzZDAtYTMyNy0xMzIxYWVjNzJjZGYifQ.QzrUxlT2rG4jvYbMDGnk23j8ZYfHJcdXPKR9CbSmcKeVpURaHhEMpPB6K4x5ut3xxeEGSzeE5VRz8vixI4iqyHsD8rSdkLTPHy0iovUHOZQBAJVQ6hii9jpLhxUXmiTtH3jKzSj_f2fuNmZbIGhf-CR2FBeWF-aBPzEDEMV95nkCUMfW_Z2BmkbraSfvQZxkCO-cLrMAwlYcrzUtaJ7vnazeQB4sep5BBHBEvsa4kfq6_tz6BAKgv3R7cI2NkSv-wgy_IGoTjVCMTS8mJHGs_t8cWCO8-z4lxW1tUwIBKOCUDpmEEnGgiG6Sl0C_gGl4bZ5cDSl4IgPpcOVi9jZ7LA",
  //   "token_type": "Bearer",
  //   "issued_at": 1680888985929,
  //   "expires_in": 28799,
  //   "status": "approved",
  //   "scope": "addresses international-prices subscriptions payments pickup tracking labels scan-forms companies service-delivery-standards locations international-labels prices",
  //   "issuer": "api.usps.com",
  //   "client_id": "hyr7b3vCRtpYtAHM1a8cdUrkyyFmNkbg",
  //   "application_name": "Silver Shipper Developer",
  //   "api_products": "[Shipping-Silver]",
  //   "public_key": "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"
  // }

  // Sample code for parsing the JSON response...
  // Use the following online tool to generate parsing code from sample JSON:
  // Generate Parsing Code from JSON

  final accessToken = jResp.stringOf('access_token');
  final tokenType = jResp.stringOf('token_type');
  final issuedAt = jResp.intOf('issued_at');
  final expiresIn = jResp.intOf('expires_in');
  final status = jResp.stringOf('status');
  final scope = jResp.stringOf('scope');
  final issuer = jResp.stringOf('issuer');
  final clientId = jResp.stringOf('client_id');
  final applicationName = jResp.stringOf('application_name');
  final apiProducts = jResp.stringOf('api_products');
  final publicKey = jResp.stringOf('public_key');
}