(C# UWP/WinRT) 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 Universal Windows Platform (UWP) / WinRT Downloads

Chilkat for the Universal Windows Platform (UWP)

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

Chilkat.Rest rest = new Chilkat.Rest();

// Connect to the destination web server.
bool bTls = true;
int port = 443;
bool bAutoReconnect = true;
bool success = await rest.ConnectAsync("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");
Chilkat.StringBuilder 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.
Chilkat.Stream fileStream = new Chilkat.Stream();
fileStream.SourceFile = "qa_data/jpg/starfish.jpg";
rest.SetMultipartBodyStream(fileStream);

string responseBody = await rest.FullRequestMultipartAsync("POST","/some_path");
if (rest.LastMethodSuccess != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

// ...
// ...

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