Lua

REST Stream Multipart Body from File

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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. Lua

local chilkat = require("chilkat")

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

local rest = chilkat.Rest.new()

-- Connect to the destination web server.
local bTls = true
local port = 443
local bAutoReconnect = true
local 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.
rest:add_header("Content-Type", "multipart/form-data")

-- Specify each part of the request.
rest.part_selector = "1"
rest:add_header("Content-Disposition", "form-data; name=\"text1\"")
rest:set_multipart_body_string("text 123 abc")

rest.part_selector = "2"
rest:add_header("Content-Disposition", "form-data; name=\"text2\"")
rest:set_multipart_body_string("xyz")

rest.part_selector = "3"
rest:add_header("Content-Disposition", "form-data; name=\"file1\"; filename=\"a.txt\"")
rest:add_header("Content-Type", "text/plain")
rest:set_multipart_body_string("Content of a.txt.")

rest.part_selector = "4"
rest:add_header("Content-Disposition", "form-data; name=\"file2\"; filename=\"a.html\"")
rest:add_header("Content-Type", "text/html")
local sbHtml = chilkat.StringBuilder.new()
sbHtml:load_file("qa_data/html/a.html", "utf-8")
rest:set_multipart_body_sb(sbHtml)

rest.part_selector = "5"
rest:add_header("Content-Disposition", "form-data; name=\"file3\"; filename=\"starfish.jpg\"")
rest:add_header("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.
local fileStream = chilkat.Stream.new()
fileStream.source_file = "qa_data/jpg/starfish.jpg"
rest:set_multipart_body_stream(fileStream)

local responseBody = rest:full_request_multipart("POST", "/some_path")
if not rest.last_method_success then
    print(rest.last_error_text)
    return
end

-- ...
-- ...

-- Clear the REST object for any subsequent requests..
rest:clear_all_headers()
rest:clear_all_parts()
rest.part_selector = ""