Dart

Building a multipart/form-data Request for HTTP Upload

See more HTTP Examples

Uploading files to a web server typically requires building a multipart/form-data request where the files are contained in the sub-parts of the MIME request.

Note: HTTP uploads require code on the server-side to receive the upload. For example, see Complete C# ASP.NET HTTP Upload Example

This example produces the following HTTP multipart/form-data request:

POST /something HTTP/1.1
Content-Type: multipart/form-data; boundary=------------070002080409050901090203
Host: domain
Content-Length: 546

--------------070002080409050901090203
Content-Disposition: form-data; name="fileA"; filename="fileA.txt"
Content-Type: text/plain

This is the contents of file A
--------------070002080409050901090203
Content-Disposition: form-data; name="fileB"; filename="fileB.txt"
Content-Type: text/plain

This is the contents of file B
--------------070002080409050901090203
Content-Disposition: form-data; name="fileC"; filename="fileC.txt"
Content-Type: text/plain

This is the contents of file C
--------------070002080409050901090203--

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example demonstrates building a multipart/form-data request.

  final req = CkHttpRequest();

  // The ContentType, HttpVerb, and Path properties should
  // always be explicitly set.
  req.httpVerb = 'POST';
  req.path = '/something';
  req.contentType = 'multipart/form-data';

  // The contents and name of each file to be uploaded is provided
  // by calling any of the following methods:
  // AddBytesForUpload
  // AddBytesForUpload2
  // AddFileForUpload
  // AddFileForUpload2
  // AddStringForUpload
  // AddStringForUpload2

  // For this example, we'll provide the contents of the files to be uploaded
  // directly as in-memory strings.
  req.addStringForUpload('fileA', 'fileA.txt', 'This is the contents of file A', 'utf-8');
  req.addStringForUpload('fileB', 'fileB.txt', 'This is the contents of file B', 'utf-8');
  req.addStringForUpload('fileC', 'fileC.txt', 'This is the contents of file C', 'utf-8');

  // View the request that would be sent if HttpSReq was called:
  final requestMime = req.generateRequestText();
  print(requestMime);

  // A few important comments about the HTTP request that is generated:
  // 
  // 1) Chilkat automatically generates a random boundary string.   In 99.999% of cases, this should 
  //    be sufficient.
  // 2) The Content-Length header is automatically generated based on the actual length of the MIME message
  //    that follows the intial (topmost) MIME header.
  // 3) The HOST header will automatically get filled in with the actual domain when HttpSReq
  //    is called.
}