Lua

Count the Related Items in an Email

Demonstrates the read-only Chilkat Email.NumRelatedItems property, which is the number of related MIME items in the email. Related items are resources — such as images or style sheets — embedded with an HTML body in a multipart/related enclosure, and are commonly referenced by the HTML using a cid: URL or a Content-Location. Indexes are zero-based. This example sets an HTML body, adds a related item, and prints the count.

Background: When an HTML email shows an image that travels inside the message (rather than being downloaded from the web), the image is a "related item." The HTML references it with <img src="cid:logo.png">, and a matching part carries a Content-ID of logo.png. The whole bundle lives in a multipart/related enclosure. This is different from an attachment: related items are meant to be displayed as part of the body, not saved as separate files.

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local chilkat = require("chilkat")

-- Demonstrates the read-only Email.NumRelatedItems property.  Related items are
-- resources (such as images or style sheets) embedded alongside an HTML body in a
-- multipart/related enclosure, typically referenced from the HTML by a cid: URL.

local email = chilkat.Email.new()

-- Set an HTML body that references a related item by content-id.
email:set_html_body("<html><body><img src=\"cid:logo.png\"/></body></html>")

-- Add the related item.  AddRelatedString returns the content-id assigned to it.
-- The empty charset argument means no charset conversion is applied.
local cid = email:add_related_string("logo.png", "(pretend this is image data)", "")
print("Related content-id = " .. cid)

print("NumRelatedItems = " .. email.num_related_items)