Zig

Get a Header Attribute of an Attached Message

Demonstrates the Chilkat Email.GetAttachedMessageAttr method, which returns a header-field attribute value for the Nth attached (embedded) email. The first argument is the zero-based attached-message index, the second is the header field name, and the third is the attribute name. This example attaches an email and reads the filename attribute of its Content-Disposition header.

Background: MIME header fields can carry named attributes (parameters) after the main value — for example Content-Disposition: attachment; filename="report.eml", where filename is an attribute. Rather than parsing the raw header yourself, this method extracts a single named attribute from a chosen header of a specific embedded message, which is convenient when a message forwards other emails as nested message/rfc822 parts.

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Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // Demonstrates the GetAttachedMessageAttr method, which returns a header-field attribute
    // value for the Nth attached (embedded) email.  The first argument is the zero-based
    // attached-message index, the second is the header field name, and the third is the attribute name.

    // Build an inner email to attach.
    const inner_email = try chilkat.Email.init();
    defer inner_email.deinit();
    inner_email.setSubject("Embedded message");
    inner_email.setFrom("alice@example.com");
    inner_email.addTo("Bob", "bob@example.com") catch {};

    // Attach it to an outer email as a message/rfc822 part.
    const email = try chilkat.Email.init();
    defer email.deinit();
    email.setSubject("Has an attached message");
    email.attachEmail(inner_email) catch {
        std.debug.print("{s}\n", .{try email.getLastErrorText(alloc)});
        return;
    };

    // Get the "filename" attribute of the "Content-Disposition" header of the first
    // attached message (index 0).
    const fname = try email.getAttachedMessageAttr(alloc, 0, "Content-Disposition", "filename");
    std.debug.print("Attached message filename attribute: {s}\n", .{fname});
}