无法使用JavaScript发送POST JSON请求

我试图用jQuery 1.9发送一个POST JSON请求。

我总是在控制台中得到以下错误。

类型错误:this.products未定义。this.products.push(oneProduct);

这是我的代码

<script src="http://code.jquery.com/jquery-latest.js"></script>
<script type="text/javascript" charset="utf-8" src="resources/js/model/Product.js"></script> 
<script>
    function getdetails(){

        var p = new Product(15,11.5,"Pizza Test","P");
        var z = new Product(68,1.5,"Zutate Test","Z");

        p.addOneProduct(z);

        var request = $.ajax({
            type: "POST",
            url: "yb_test_post.php",
            dataType: "json",
            data: p
        });

        request.done(function(msg) {
            $("#msg").html( " Post parameter are: <br/>"+msg );
        });

        request.fail(function(jqXHR, textStatus) {
            alert( "Request failed: " + textStatus );
        });
    }
</script>

和产品.js

   function Product(id, price, name, type){
    this.id = id;
    this.price = +price;
    this.totalPrice = +price;
    this.name = name;
    this.type = type;
    this.products = [];

    this.addOneProduct = function(oneProduct){
        this.products.push(oneProduct);
        this.totalPrice= this.totalPrice+oneProduct.price;
    };
  }

我做错了什么?