(Lianja) 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 Lianja Extension Download

Chilkat Lianja Extension

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

loRest = createobject("CkRest")

// Connect to the destination web server.
llBTls = .T.
lnPort = 443
llBAutoReconnect = .T.
llSuccess = loRest.Connect("www.somewebserver.com",lnPort,llBTls,llBAutoReconnect)

// 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.
loRest.AddHeader("Content-Type","multipart/form-data")

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

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

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

loRest.PartSelector = "4"
loRest.AddHeader("Content-Disposition",'form-data; name="file2"; filename="a.html"')
loRest.AddHeader("Content-Type","text/html")
loSbHtml = createobject("CkStringBuilder")
loSbHtml.LoadFile("qa_data/html/a.html","utf-8")
loRest.SetMultipartBodySb(loSbHtml)

loRest.PartSelector = "5"
loRest.AddHeader("Content-Disposition",'form-data; name="file3"; filename="starfish.jpg"')
loRest.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.
loFileStream = createobject("CkStream")
loFileStream.SourceFile = "qa_data/jpg/starfish.jpg"
loRest.SetMultipartBodyStream(loFileStream)

lcResponseBody = loRest.FullRequestMultipart("POST","/some_path")
if (loRest.LastMethodSuccess <> .T.) then
    ? loRest.LastErrorText
    release loRest
    release loSbHtml
    release loFileStream
    return
endif

// ...
// ...

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


release loRest
release loSbHtml
release loFileStream