Greetings earthlings!

I'm trying to add a field (and show it), in the chat area of any document. Unfortunately, although the program is not showing any error, it simply will not do what I want (the new stuff is not loaded)...

odoo.define('mymodule.model.AbstractMessage', function (require) {

"use strict";

    var AbstractMessage = require('mail.model.AbstractMessage');

    var myAbstractMessage = AbstractMessage.extend({

        init: function (parent, data) {

            this._read_by = data.read_by;

            this._super.apply(this, arguments);

        },

        getReadBy: function () {

            return this._read_by;

        },

    });

    return myAbstractMessage;

});