(Node.js) 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.

Install Chilkat for Node.js and Electron using npm at

Chilkat npm packages for Node.js
Chilkat npm packages for Electron
on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

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

    var rest = new chilkat.Rest();

    // Connect to the destination web server.
    var bTls = true;
    var port = 443;
    var bAutoReconnect = true;
    var success = rest.Connect("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.
    rest.AddHeader("Content-Type","multipart/form-data");

    // Specify each part of the request.
    rest.PartSelector = "1";
    rest.AddHeader("Content-Disposition","form-data; name=\"text1\"");
    rest.SetMultipartBodyString("text 123 abc");

    rest.PartSelector = "2";
    rest.AddHeader("Content-Disposition","form-data; name=\"text2\"");
    rest.SetMultipartBodyString("xyz");

    rest.PartSelector = "3";
    rest.AddHeader("Content-Disposition","form-data; name=\"file1\"; filename=\"a.txt\"");
    rest.AddHeader("Content-Type","text/plain");
    rest.SetMultipartBodyString("Content of a.txt.");

    rest.PartSelector = "4";
    rest.AddHeader("Content-Disposition","form-data; name=\"file2\"; filename=\"a.html\"");
    rest.AddHeader("Content-Type","text/html");
    var sbHtml = new chilkat.StringBuilder();
    sbHtml.LoadFile("qa_data/html/a.html","utf-8");
    rest.SetMultipartBodySb(sbHtml);

    rest.PartSelector = "5";
    rest.AddHeader("Content-Disposition","form-data; name=\"file3\"; filename=\"starfish.jpg\"");
    rest.AddHeader("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.
    var fileStream = new chilkat.Stream();
    fileStream.SourceFile = "qa_data/jpg/starfish.jpg";
    rest.SetMultipartBodyStream(fileStream);

    var responseBody = rest.FullRequestMultipart("POST","/some_path");
    if (rest.LastMethodSuccess !== true) {
        console.log(rest.LastErrorText);
        return;
    }

    // ...
    // ...

    // Clear the REST object for any subsequent requests..
    rest.ClearAllHeaders();
    rest.ClearAllParts();
    rest.PartSelector = "";

}

chilkatExample();