Lua

Convert a MIME Entity to multipart/alternative

Demonstrates the Chilkat Mime.ConvertToMultipartAlt method, which wraps the current entity in a new outer multipart/alternative, making the original the first child. It takes no arguments.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: Use this to add an alternate rendering to an existing message — for example, promoting a plain-text message so an HTML version can be added alongside it. The original content becomes the first (least-preferred) alternative, and you append the richer representation after it. As with the mixed conversion, message-level headers move to the new outer entity.

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Lua

local chilkat = require("chilkat")

local mime = chilkat.Mime.new()
local success = mime:load_mime_file("qa_data/message.eml")
if not success then
    print(mime.last_error_text)
    return
end

-- Wrap the current entity in a new outer multipart/alternative entity.  The original entity
-- becomes the first child, ready for an alternate representation to be added.
success = mime:convert_to_multipart_alt()
if not success then
    print(mime.last_error_text)
    return
end

-- Add an alternative representation of the same content.
local htmlPart = chilkat.Mime.new()
success = htmlPart:set_body_from_html("<html><body>HTML alternative.</body></html>")
if not success then
    print(htmlPart.last_error_text)
    return
end

success = mime:append_part(htmlPart)
if not success then
    print(mime.last_error_text)
    return
end

print("Number of parts: " .. mime.num_parts)