Dart

HTTPS multipart/form-data POST

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Demonstrates how to send a multipart/form-data POST over HTTPS (using TLS). Dart

import 'package:chilkat/chilkat.dart';

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

  // This example demonstrates how to send a multipart/form-data POST that
  // looks like this:

  // 	POST /cgi/XXX.pl HTTP/1.0
  // 	Accept: text/html
  // 	Connection: Keep-Alive
  // 	User-Agent: XXX/8.0.15
  // 	Content-type: multipart/form-data, boundary=XXXxyxy
  // 	Content-Length: 682
  // 
  // 	--XXXxyxy
  // 	content-disposition: form-data; name="UploadAgent"
  // 
  // 	InterfaceVersion1.5
  // 	--XXXxyxy
  // 	content-disposition: form-data; name="user"
  // 
  // 	userValue
  // 	--XXXxyxy
  // 	content-disposition: form-data; name="password"
  // 
  // 	passwordValue
  // 	--XXXxyxy
  // 	content-disposition: form-data; name="file"
  // 
  // 	fileValue
  // 	--XXXxyxy
  // 	content-disposition: form-data; name="data_version"
  // 
  // 	dataVersion
  // 	--XXXxyxy
  // 	content-disposition: form-data; name="content2"; filename="XXX"
  // 
  // 	THE FILE CONTENT GOES HERE...
  // 	--XXXxyxy--
  // 

  // First, let's build the HTTP request object
  final req = CkHttpRequest();

  req.httpVerb = 'POST';
  req.path = '/cgi/XXX.pl';

  // The boundary string is automatically generated and added by Chilkat.
  // The value for the boundary string doesn't matter. (As long as it's a unique string that doesn't occur elsewhere in the request.)
  req.contentType = 'multipart/form-data';

  // Adding the Connection: Keep-Alive is optional.  It only makes sense if the intent is to send
  // additional requests to the same domain (your-namespace-sb.accesscontrol.windows.net) within a reasonable time period.
  req.addHeader('Connection', 'Keep-Alive');

  // --------------------------------------------------
  // IMPORTANT: Never set the Content-Length header.  
  // Chilkat will automatically compute the correct Content-Length and will add it.
  // --------------------------------------------------

  // If a specific User-Agent header field is needed, it can be added by calling AddHeader.
  req.addHeader('User-Agent', 'XXX/8.0.15');

  // The "Accept" header, if present, tells the server what Content-Type responses will be accepted.
  // In this case, we're telling the server that we'll only accept "text/html" responses, and therefore
  // the server SHOULD only send a text/html response.  Technically, the Accept header is not required.
  req.addHeader('Accept', 'text/html');

  // Add the params to the request.  Given that the Content-Type is set to "multipart/form-data", when
  // Chilkat composes the request, it will put each param in it's own MIME sub-part (i.e. in it's own
  // part delimited by the boundary string).
  req.addParam('UploadAgent', 'InterfaceVersion1.5');
  req.addParam('user', 'userValue');
  req.addParam('password', 'passwordValue');
  req.addParam('file', 'fileValue');
  req.addParam('data_version', 'dataVersion');

  // The last param is the contents of a file.
  // If it's a file on disk, we can add it like this:
  final pathToFileOnDisk = 'c:/someDir/someFile.dat';
  try {
    req.addFileForUpload('content2', pathToFileOnDisk);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Alternatively, if the contents of the file are in memory, perhaps in a string
  // variable, the file can be added like this instead.
  final fileContents = 'This is the content of the file being uploaded.';
  req.addStringForUpload('content2', 'XXX', fileContents, 'utf-8');

  // -----------------------------------------------------------
  // IMPORTANT: To duplicate the HTTP request shown above, you'll want to choose 
  // either AddStringForUpload or AddFileForUpload, but not both.  It's possible to upload
  // any number of files by calling AddStringForUpload and/or AddFileForUpload any number
  // of times, once per file to be uploaded.  This of course assumes that the receiving
  // end is programmed to receive multiple files..
  // ------------------------------------------------------------

  final http = CkHttp();

  // The request is ready... now send it using HTTPS (which is port 443 by default).

  final resp = CkHttpResponse();
  try {
    http.httpSReq('www.myserver.com', 443, true, req, resp);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('HTTP response status: ${resp.statusCode}');

  // In this case, the response would be HTML because our Accept header
  // told the server to only return HTML.  The HTML is available on the BodyStr
  // property of the response object:
  final htmlStr = resp.bodyStr;
  print('Received:');
  print(htmlStr);
}