Zig

Add, Remove, Update MIME Header Fields

See more MIME Examples

Demonstrates how to add, remove, or update the content of MIME header fields. Zig

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

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

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    const mime = try chilkat.Mime.init();
    defer mime.deinit();

    // The contents of this MIME file are shown below,
    // and is also available at https://www.chilkatsoft.com/sampleMime.txt
    mime.loadMimeFile("qa_data/mime/sampleMime.txt") catch {
        std.debug.print("{s}\n", .{try mime.getLastErrorText(alloc)});
        return;
    };

    // The MIME used in this example has the following nested structure
    //
    // multipart/alternative
    //     text/plain
    //     multipart/related
    //         text/html
    //         image/jpeg
    //

    // Adding a top-level MIME header is easy.
    mime.addHeaderField("hello-world", "Hello World!") catch {};
    // If a header field of the same name already exists, the AddHeaderField
    // method adds a duplicate.
    mime.addHeaderField("Subject", "This is the 2nd Subject header.") catch {};
    std.debug.print("{s}\n", .{try mime.getEntireHead(alloc)});
    std.debug.print("-\n", .{});

    // The top-level header now looks like this:
    //
    //     Subject: Test email.
    //     Content-Type: multipart/alternative; boundary="------------DB171738719FB06D67DEBAA0"
    //     MIME-Version: 1.0
    //     hello-world: Hello World!
    //     Subject: This is the 2nd Subject header.
    //

    // The RemoveHeaderField method can remove the 1st occurrance, or all occurrences.
    const b_all_occurrences = true;
    // Remove all occurrences of the Subject header;
    mime.removeHeaderField("Subject", b_all_occurrences);
    std.debug.print("{s}\n", .{try mime.getEntireHead(alloc)});
    std.debug.print("-\n", .{});

    // After removing all Subject header fields, the top-level header now looks like this:
    //
    // Content-Type: multipart/alternative; boundary="------------DB171738719FB06D67DEBAA0"
    // MIME-Version: 1.0
    // hello-world: Hello World!
    //

    // The content of a header field can be updated by calling SetHeaderField.
    // If the header field does not already exist, it is added.  Otherwise it is updated.
    // Note: The order of header fields SHOULD never matter.
    mime.setHeaderField("hello-world", "Goodbye World.") catch {};
    std.debug.print("{s}\n", .{try mime.getEntireHead(alloc)});
    std.debug.print("-\n", .{});

    // Now we have:
    //
    //     Content-Type: multipart/alternative; boundary="------------DB171738719FB06D67DEBAA0"
    //     MIME-Version: 1.0
    //     hello-world: Goodbye World.
    //

    // To add/update/delete header fields in sub-parts, navigate to
    // the sub-part and do the same..

    const mp_related = try chilkat.Mime.init();
    defer mp_related.deinit();
    mime.partAt(1, mp_related) catch {};

    const p_jpg = try chilkat.Mime.init();
    defer p_jpg.deinit();
    mp_related.partAt(1, p_jpg) catch {};

    // Add a header to the image/jpeg sub-header.
    p_jpg.setHeaderField("CustomHeader", "This is the custom header value.") catch {};

    // View the entire MIME..
    std.debug.print("{s}\n", .{try mime.getMime(alloc)});

    // --------------------------------------------------------------
    // --------------------------------------------------------------
    // The MIME sample file loaded at the beginning of this example
    // contains the following MIME:

    // Subject: Test email.
    // Content-Type: multipart/alternative;
    //     boundary="------------DB171738719FB06D67DEBAA0"
    // MIME-Version: 1.0
    //
    // --------------DB171738719FB06D67DEBAA0
    // Content-Type: text/plain; charset="utf-8"; format=flowed
    // Content-Transfer-Encoding: 7bit
    //
    // This is a test.
    //
    // --------------DB171738719FB06D67DEBAA0
    // Content-Type: multipart/related;
    //     boundary="------------A940F1230E6F0105F03DB2CB"
    //
    // --------------A940F1230E6F0105F03DB2CB
    // Content-Type: text/html; charset="utf-8"
    // Content-Transfer-Encoding: 8bit
    //
    // <html><head>
    // <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    //   </head>
    //   <body bgcolor="#FFFFFF" text="#000000">
    //     <p>This is a test.&nbsp; <img src="cid:part1.E16AE3B4.1505C436@chilkatsoft.com" height="20" width="20"></p>
    //   </body>
    // </html>
    //
    // --------------A940F1230E6F0105F03DB2CB
    // Content-Type: image/jpeg; name="starfish20.jpg"
    // Content-Transfer-Encoding: base64
    // Content-ID: <part1.E16AE3B4.1505C436@chilkatsoft.com>
    // Content-Disposition: inline; filename="starfish20.jpg"
    //
    // /9j/4AAQSkZJRgABAQEASABIAAD//gAmRmlsZSB3cml0dGVuIGJ5IEFkb2JlIFBob3Rvc2hvcD8g
    // NC4w/9sAQwAQCwwODAoQDg0OEhEQExgoGhgWFhgxIyUdKDozPTw5Mzg3QEhcTkBEV0U3OFBtUVdf
    // YmdoZz5NcXlwZHhcZWdj/9sAQwEREhIYFRgvGhovY0I4QmNjY2NjY2NjY2NjY2NjY2NjY2NjY2Nj
    // Y2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2Nj/8IAEQgAFAAUAwERAAIRAQMRAf/EABcAAAMBAAAA
    // AAAAAAAAAAAAAAIDBAX/xAAYAQADAQEAAAAAAAAAAAAAAAABAgMEAP/aAAwDAQACEAMQAAAB2kZY
    // NNEijWKddfTmLgALWH//xAAbEAACAgMBAAAAAAAAAAAAAAABAgMRAAQSE//aAAgBAQABBQL0XqN+
    // pM2aqJGMiqFFCyg7z//EABwRAAICAgMAAAAAAAAAAAAAAAERAAIQIQMSUf/aAAgBAwEBPwHqU5aq
    // Axx+y1tMQl4elj//xAAcEQEAAQUBAQAAAAAAAAAAAAABEQACEBIhA1H/2gAIAQIBAT8B3Bhqy7Zc
    // enyiwmGgDhiOzj//xAAdEAABAwUBAAAAAAAAAAAAAAABAAIREBIhIkFR/9oACAEBAAY/ArZyn+Cg
    // xtxWuJaoCnqDuin/xAAcEAABBAMBAAAAAAAAAAAAAAABABEhYRAxQVH/2gAIAQEAAT8hkEwPUUR9
    // DYfE4nxtRpIkBTsayuALIiuY/9oADAMBAAIAAwAAABDWPTsf/8QAGhEAAwADAQAAAAAAAAAAAAAA
    // AAEREDFBIf/aAAgBAwEBPxC0DVPcWm+Ce4OesrkE6bjH/8QAGBEBAQEBAQAAAAAAAAAAAAAAAREA
    // QRD/2gAIAQIBAT8QahMiOc8YgSrnTY3ELclHXn//xAAcEAEBAAIDAQEAAAAAAAAAAAABEQAhMUFx
    // EFH/2gAIAQEAAT8Qn3igmSZSj+c4N4zapMy9IjFV98wncN2iuLFsCEbDGxQkI6RO/n//2Q==
    //
    // --------------A940F1230E6F0105F03DB2CB--
    //
    // --------------DB171738719FB06D67DEBAA0--
    //
}