Zig

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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Zig

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

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

    const mime = try chilkat.Mime.init();
    defer mime.deinit();
    mime.loadMimeFile("qa_data/message.eml") catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    // 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.
    mime.convertToMultipartAlt() catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    // Add an alternative representation of the same content.
    const html_part = try chilkat.Mime.init();
    defer html_part.deinit();
    html_part.setBodyFromHtml("<html><body>HTML alternative.</body></html>") catch {
        std.debug.print("{s}\n", .{try html_part.getLastErrorText(alloc)});
        return;
    };

    mime.appendPart(html_part) catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("Number of parts: {d}\n", .{mime.getNumParts()});
}