Dear all,

I am using Odoo 12 Point of Sale, and have found on several modules, references to "at least" 3 methods.

For instance:

var _super_orderline = models.Orderline.prototype;
    models.Orderline = models.Orderline.extend
    ({   initialize: function(attr, options)
        {   _super_orderline.initialize.call(this,attr,options);
            this.product_variants = this.product_variants || [];
        },
        init_from_JSON: function(json)
        {   _super_orderline.init_from_JSON.apply(this,arguments);
            this.product_variants = json.product_variants || [];
        },
        export_as_JSON: function ()
        {   var json = _super_orderline.export_as_JSON.apply(this, arguments);
            json.product_variants = this.product_variants || [];
            return json;
        },
    });

My question are:
- What is the "initialize", "init_from_JSON" and "export_as_JSON" functions and when we should be using them?
- Are those functions applied to both Order and orderline?

Thank you very mucu in advance