(Delphi DLL) REST Stream Multipart Body from File

Demonstrates how to send a multipart/form-data HTTP request, where one of the parts contains data streamed directly from a file. This is good for cases where the file to be uploaded is very large.

Chilkat for Delphi Downloads

Chilkat non-ActiveX DLL for Delphi

Chilkat ActiveX DLL for Delphi

* The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, StringBuilder, Rest, Stream;

...

procedure TForm1.Button1Click(Sender: TObject);
var
rest: HCkRest;
bTls: Boolean;
port: Integer;
bAutoReconnect: Boolean;
success: Boolean;
sbHtml: HCkStringBuilder;
fileStream: HCkStream;
responseBody: PWideChar;

begin
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

rest := CkRest_Create();

// Connect to the destination web server.
bTls := True;
port := 443;
bAutoReconnect := True;
success := CkRest_Connect(rest,'www.somewebserver.com',port,bTls,bAutoReconnect);

// This example will send the following multipart/form-data request.
// The Content-Length is automatically computed and added by Chilkat.

// 	POST /some_path HTTP/1.1
// 	Content-Type: multipart/form-data; boundary=---------------------------735323031399963166993862150
// 	Content-Length: 834
// 
// 	-----------------------------735323031399963166993862150
// 	Content-Disposition: form-data; name="text1"
// 
// 	text 123 abc
// 	-----------------------------735323031399963166993862150
// 	Content-Disposition: form-data; name="text2"
// 
// 	xyz
// 	-----------------------------735323031399963166993862150
// 	Content-Disposition: form-data; name="file1"; filename="a.txt"
// 	Content-Type: text/plain
// 
// 	Content of a.txt.
// 
// 	-----------------------------735323031399963166993862150
// 	Content-Disposition: form-data; name="file2"; filename="a.html"
// 	Content-Type: text/html
// 
// 	<!DOCTYPE html><title>Content of a.html.</title>
// 
// 	-----------------------------735323031399963166993862150
// 	Content-Disposition: form-data; name="file3"; filename="starfish.jpg"
// 	Content-Type: image/jpeg
// 
// 	binary data goes here
// 	-----------------------------735323031399963166993862150--

// Set the Content-Type for the topmost MIME part.
CkRest_AddHeader(rest,'Content-Type','multipart/form-data');

// Specify each part of the request.
CkRest_putPartSelector(rest,'1');
CkRest_AddHeader(rest,'Content-Disposition','form-data; name="text1"');
CkRest_SetMultipartBodyString(rest,'text 123 abc');

CkRest_putPartSelector(rest,'2');
CkRest_AddHeader(rest,'Content-Disposition','form-data; name="text2"');
CkRest_SetMultipartBodyString(rest,'xyz');

CkRest_putPartSelector(rest,'3');
CkRest_AddHeader(rest,'Content-Disposition','form-data; name="file1"; filename="a.txt"');
CkRest_AddHeader(rest,'Content-Type','text/plain');
CkRest_SetMultipartBodyString(rest,'Content of a.txt.');

CkRest_putPartSelector(rest,'4');
CkRest_AddHeader(rest,'Content-Disposition','form-data; name="file2"; filename="a.html"');
CkRest_AddHeader(rest,'Content-Type','text/html');
sbHtml := CkStringBuilder_Create();
CkStringBuilder_LoadFile(sbHtml,'qa_data/html/a.html','utf-8');
CkRest_SetMultipartBodySb(rest,sbHtml);

CkRest_putPartSelector(rest,'5');
CkRest_AddHeader(rest,'Content-Disposition','form-data; name="file3"; filename="starfish.jpg"');
CkRest_AddHeader(rest,'Content-Type','image/jpeg');

// When the request is sent, stream this part directly from the file.
// This avoids having to load the entire file into memory.
fileStream := CkStream_Create();
CkStream_putSourceFile(fileStream,'qa_data/jpg/starfish.jpg');
CkRest_SetMultipartBodyStream(rest,fileStream);

responseBody := CkRest__fullRequestMultipart(rest,'POST','/some_path');
if (CkRest_getLastMethodSuccess(rest) <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

// ...
// ...

// Clear the REST object for any subsequent requests..
CkRest_ClearAllHeaders(rest);
CkRest_ClearAllParts(rest);
CkRest_putPartSelector(rest,'');

CkRest_Dispose(rest);
CkStringBuilder_Dispose(sbHtml);
CkStream_Dispose(fileStream);

end;