Rust

Set a MIME Body, Preserving Content Headers

Demonstrates the Chilkat Mime.SetBody method, which sets the current part's body while preserving the existing content headers (Content-Type, charset, Content-Transfer-Encoding). The only argument is the body text; it is a void method.

Background: Unlike the SetBodyFrom... methods, which set both the content and the headers that describe it, SetBody replaces only the body text and leaves the existing Content-Type and encoding in place. That is what you want when the media type is already correct and you simply need to swap in new content — updating a templated part, for instance — without re-declaring its type.

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// Demonstrates the Mime.SetBody method, which sets the current part's body while preserving the
// existing content headers (Content-Type, charset, Content-Transfer-Encoding).  The only argument
// is the body text.  It is a void method.

let mime = chilkat::Mime::new();

// Establish the content headers first.
if mime.set_body_from_plain_text("initial").is_err() {
    println!("{}", mime.last_error_text());
    return;
}

// Replace just the body text, keeping the existing Content-Type and encoding.
mime.set_body("This is the replacement body text.");

let Ok(mime_text) = mime.get_mime() else {
    println!("{}", mime.last_error_text());
    return;
};

println!("{}", mime_text);