Dart

HTTP POST and Stream Response to File

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Demonstrates how to send an HTTP POST and stream the response body directly to a file. Dart

import 'package:chilkat/chilkat.dart';

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

  final rest = CkRest();

  final url = CkUrl();
  // This URL will emit a response that echos the query params (name and age)
  url.parseUrl('https://www.chilkatsoft.com/readPost.asp');

  // Connect to the web server
  final bAutoReconnect = true;
  try {
    rest.connect(url.host, url.port, url.ssl, bAutoReconnect);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  rest.addQueryParam('name', 'John');
  rest.addQueryParam('age', '33');

  //  Send the HTTP POST.
  try {
    rest.sendReqFormUrlEncoded('POST', url.path);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

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

  print('Response status code = $responseStatusCode');

  // We expect a 200 response status if the file data is coming.
  // Otherwise, we'll get a string response body with an error message(or no response body).
  if (responseStatusCode == 200) {

    final bodyStream = CkStream();

    // The stream's sink will be a file.
    bodyStream.sinkFile = 'qa_output/out.txt';

    // Read the response body to the stream.  Given that we've
    // set the stream's sink to a file, it will stream directly
    // to the file.
    try {
      rest.readRespBodyStream(bodyStream, true);
    } on ChilkatException catch (e) {
      print(e.lastErrorText);
      return;
    }

    print('Successfully streamed the response to a file.');
  } else {
    try {
      final errResponse = rest.readRespBodyString();
      print(errResponse);
    } on ChilkatException catch (e) {
      print(e.lastErrorText);
    }
  }
}