Pascal (Lazarus/Delphi)

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--

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.HttpRequest;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  req: THttpRequest;
  requestMime: string;

begin
  //  This example demonstrates building a multipart/form-data request.

  req := THttpRequest.Create;

  //  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:
  requestMime := req.GenerateRequestText();
  WriteLn(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.


  req.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.