Lua

Enumerate MIME Header Field Names

Demonstrates the Chilkat Mime.GetHeaderFieldName method, which returns the name of the header-field occurrence at a zero-based index. The only argument is the index; use NumHeaderFields for the count. Original order and casing are preserved.

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

Background: When you need to walk all the headers — to display them, copy them, or handle duplicates that GetHeaderField would hide — index-based access is the way. NumHeaderFields bounds the loop, and this returns each field's name in its original order and casing, which matters when the exact header sequence is significant.

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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

-- Iterate the header fields by index.  NumHeaderFields gives the count; GetHeaderFieldName and
-- GetHeaderFieldValue return the name and value at each zero-based index.  Original order and
-- casing are preserved.
local n = mime.num_header_fields
print("Header fields: " .. n)
for i = 0, n - 1 do
    local fieldName = mime:get_header_field_name(i)
    if not mime.last_method_success then
        print(mime.last_error_text)
        return
    end

    print(fieldName)
end