Dart

Egyptian eReceipt OAuth2 Client Credentials

See more Egypt eReceipt Examples

Get an OAuth2 access token for the Egyptian eReceipt REST API using client credentials (no interactivity with a web browser required). 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();

  // Note: Any provider of a REST API, such as the Egyptian government in this case, can make life 
  // much easier for developers by providing one or more of the following in the API documentation:
  // 
  // 1) A sample CURL statement for each API call.
  // 2) A Postman collection, or Swagger/OpenAPI specification file.
  // 3) A sample of a raw HTTP request and response for each API call.
  // 
  // The sample CURL statements or raw HTTP request/responses do not need to comprehensively show all 
  // possible options.  Providing a sample allows one to quickly make a successful API call.
  // It also allows for code generation directly from the CURL, Postman collection, or raw request/response,
  // and it tends to answer all questions about the format/structure of a request that, suprisingly,
  // remain ambiguous or not obvious in other forms of documentation.

  final req = CkHttpRequest();
  req.addParam('grant_type', 'client_credentials');
  // Use your actual client ID and client secret...
  req.addParam('client_id', 'd0394a9f-0607-40de-a978-2d3eb8375b04');
  req.addParam('client_secret', '6d62315e-d65a-4e41-9112-4195ea834edf');

  req.addHeader('posserial', '1234567899');
  req.addHeader('pososversion', 'os');
  req.addHeader('posmodelframework', '1');
  req.addHeader('presharedkey', '03ac674216f3e1...');

  // When writing this example, the documentation at https://sdk.invoicing.eta.gov.eg/ereceiptapi/01-authenticate-pos/
  // shows us the HTTP verb and path (POST /connect/token), however,
  // we don't see the actual domain where the request is to be sent.
  // What are the endpoints???
  // It took some searching, but we found some endpoints here:  https://sdk.invoicing.eta.gov.eg/faq/
  // It's not immediately apparent which endpoint is to be used with a given API call.
  // Why not just include the endpoint in the documentation for each REST API call?
  // Endpoints are literally the #1 thing that needs to be known.
  // They can't just be buried in a FAQ.  They should be up-front and obvious.
  // 
  // So.. we're guessing the endpoint is likely "https://invoicing.eta.gov.eg/connect/token"
  req.httpVerb = 'POST';
  req.contentType = 'application/x-www-form-urlencoded';

  final resp = CkHttpResponse();
  try {
    http.httpReq('https://invoicing.eta.gov.eg/connect/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;
  }

  // If successful, the OAuth2 access token JSON looks like this:

  // {
  //   "token_type": "Bearer",
  //   "access_token": "eyJraW......R2sbqrY",
  //   "expires_in": "3600",
  //   "scope": "..."
  // }

  final tokenType = jResp.stringOf('token_type');
  final accessToken = jResp.stringOf('access_token');
  final expiresIn = jResp.stringOf('expires_in');
  final scope = jResp.stringOf('scope');
}