(Tcl) Building a multipart/form-data Request for HTTP Upload

Uploading files to a web server typically requires building a multipart/form-data request where the files are contained in the sub-parts of the MIME request.

Note: HTTP uploads require code on the server-side to receive the upload. For example, see Complete C# ASP.NET HTTP Upload Example

This example produces the following HTTP multipart/form-data request:

POST /something HTTP/1.1
Content-Type: multipart/form-data; boundary=------------070002080409050901090203
Host: domain
Content-Length: 546

--------------070002080409050901090203
Content-Disposition: form-data; name="fileA"; filename="fileA.txt"
Content-Type: text/plain

This is the contents of file A
--------------070002080409050901090203
Content-Disposition: form-data; name="fileB"; filename="fileB.txt"
Content-Type: text/plain

This is the contents of file B
--------------070002080409050901090203
Content-Disposition: form-data; name="fileC"; filename="fileC.txt"
Content-Type: text/plain

This is the contents of file C
--------------070002080409050901090203--

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load ./chilkat.dll

# This example demonstrates building a multipart/form-data request.

set req [new_CkHttpRequest]

# The ContentType, HttpVerb, and Path properties should
# always be explicitly set.
CkHttpRequest_put_HttpVerb $req "POST"
CkHttpRequest_put_Path $req "/something"
CkHttpRequest_put_ContentType $req "multipart/form-data"

# The contents and name of each file to be uploaded is provided
# by calling any of the following methods:
# AddBytesForUpload
# AddBytesForUpload2
# AddFileForUpload
# AddFileForUpload2
# AddStringForUpload
# AddStringForUpload2

# For this example, we'll provide the contents of the files to be uploaded
# directly as in-memory strings.
CkHttpRequest_AddStringForUpload $req "fileA" "fileA.txt" "This is the contents of file A" "utf-8"
CkHttpRequest_AddStringForUpload $req "fileB" "fileB.txt" "This is the contents of file B" "utf-8"
CkHttpRequest_AddStringForUpload $req "fileC" "fileC.txt" "This is the contents of file C" "utf-8"

# View the request that would be sent if SynchronousRequest was called:
set requestMime [CkHttpRequest_generateRequestText $req]
puts "$requestMime"

# A few important comments about the HTTP request that is generated:
# 
# 1) Chilkat automatically generates a random boundary string.   In 99.999% of cases, this should 
#    be sufficient.
# 2) The Content-Length header is automatically generated based on the actual length of the MIME message
#    that follows the intial (topmost) MIME header.
# 3) The HOST header will automatically get filled in with the actual domain when SynchronousRequest
#    is called

delete_CkHttpRequest $req