(Tcl) 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 Tcl Extension Downloads

Chilkat Tcl Extension Downloads

load ./chilkat.dll

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

set rest [new_CkRest]

# Connect to the destination web server.
set bTls 1
set port 443
set bAutoReconnect 1
set 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_put_PartSelector $rest "1"
CkRest_AddHeader $rest "Content-Disposition" "form-data; name=\"text1\""
CkRest_SetMultipartBodyString $rest "text 123 abc"

CkRest_put_PartSelector $rest "2"
CkRest_AddHeader $rest "Content-Disposition" "form-data; name=\"text2\""
CkRest_SetMultipartBodyString $rest "xyz"

CkRest_put_PartSelector $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_put_PartSelector $rest "4"
CkRest_AddHeader $rest "Content-Disposition" "form-data; name=\"file2\"; filename=\"a.html\""
CkRest_AddHeader $rest "Content-Type" "text/html"
set sbHtml [new_CkStringBuilder]

CkStringBuilder_LoadFile $sbHtml "qa_data/html/a.html" "utf-8"
CkRest_SetMultipartBodySb $rest $sbHtml

CkRest_put_PartSelector $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.
set fileStream [new_CkStream]

CkStream_put_SourceFile $fileStream "qa_data/jpg/starfish.jpg"
CkRest_SetMultipartBodyStream $rest $fileStream

set responseBody [CkRest_fullRequestMultipart $rest "POST" "/some_path"]
if {[CkRest_get_LastMethodSuccess $rest] != 1} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    delete_CkStringBuilder $sbHtml
    delete_CkStream $fileStream
    exit
}

# ...
# ...

# Clear the REST object for any subsequent requests..
CkRest_ClearAllHeaders $rest
CkRest_ClearAllParts $rest
CkRest_put_PartSelector $rest ""

delete_CkRest $rest
delete_CkStringBuilder $sbHtml
delete_CkStream $fileStream