(Excel) 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.

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Chilkat Excel Class Modules

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

Dim rest As Chilkat.Rest
Set rest = Chilkat.NewRest

' Connect to the destination web server.

bTls = True

port = 443

bAutoReconnect = True

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.
Dim success As Boolean
success = rest.AddHeader("Content-Type","multipart/form-data")

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

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

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

rest.PartSelector = "4"
success = rest.AddHeader("Content-Disposition","form-data; name=""file2""; filename=""a.html""")
success = rest.AddHeader("Content-Type","text/html")
Dim sbHtml As Chilkat.StringBuilder
Set sbHtml = Chilkat.NewStringBuilder
success = sbHtml.LoadFile("qa_data/html/a.html","utf-8")
success = rest.SetMultipartBodySb(sbHtml)

rest.PartSelector = "5"
success = rest.AddHeader("Content-Disposition","form-data; name=""file3""; filename=""starfish.jpg""")
success = 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.
Dim fileStream As Chilkat.Stream
Set fileStream = Chilkat.NewStream
fileStream.SourceFile = "qa_data/jpg/starfish.jpg"
success = rest.SetMultipartBodyStream(fileStream)


responseBody = rest.FullRequestMultipart("POST","/some_path")
If (rest.LastMethodSuccess <> True) Then
    Debug.Print rest.LastErrorText
    Exit Sub
End If

' ...
' ...

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