流星在会话中存储和检索自定义对象 [英] Meteor Storing and Retrieving Custom Objects in Session

问题描述

我创建了一个自定义购物车对象并将其放在 lib 文件夹中。

I have a custom shopping cart object that I created and put it in the lib folder.

ShoppingCart = function ShoppingCart() {
  this.Items = new Array();
  this.grandTotal = 0.00;
}

ShoppingCart.prototype.addItem = function(Item){
  this.Items.push(Item);
  this.Items.sort();
  this.calculateTotal();
}

我初始化购物车并将其存储为会话页面创建阶段.set（'shoppingCart'）。

I initialized the shopping cart and store it as Session.set('shoppingCart') during the page created phase.

Template.loginStatus.created = function() {
  Session.set('loginShown',false);
  if(!Session.get('shoppingCart')){ //set default if session shopping cart not exist
    var cart = new ShoppingCart();
    Session.setDefault('shoppingCart',cart);
  }

然后当用户点击将项目添加到购物车时，它将触发此逻辑：

Then when user click add item to cart, it will trigger this logic:

var cart = Session.get('shoppingCart');
cart.addItem(item);
Session.set('shoppingCart',cart);

不知何故，它不起作用。当我看一下chrome控制台时，它说 undefined不是函数，指向 cart.addItem（item）线。如果我将其更改为此，它将起作用，但当然，因为每次创建新购物车时，我都无法累积购物车中的商品。

Somehow, it does not work. When I take a look ad the chrome console it says undefined is not a function, pointing at cart.addItem(item) line. If I change it to this, it will work , but of course since everytime new shopping cart is created, I cannot accumulate items in the cart.

var cart = new ShoppingCart();
cart.addItem(item);
Session.set('shoppingCart',cart);

我应该如何正确地存储和检索会话中的对象？它看起来像Session.get（）中返回的对象不知何故不被视为ShoppingCart。我错过了任何类型演员吗？

How should I store and retrieve the object from session properly? It looks like the returned object from the Session.get() somehow not considered as ShoppingCart. Did I miss any type cast?

推荐答案

作为 @ Peppe LG 提到，你只能在Session中存储EJSON。要存储自定义对象，您需要能够在EJSONs之间手动转换它。示例：

As @Peppe L-G mentioned, you can only store EJSONs in Session. To store your custom object, you need to be able to manually transform it to and from EJSONs. Example:

_.extend(ShoppingCart, {
  fromJSON: function(json) {
    var obj = new ShoppingCart();
    obj.grandTotal = json.grandTotal;
    obj.Items = json.Items;
    return obj;
  },
});

_.extend(ShoppingCart.prototype, {
  toJSON: function() {
    return {
      grandTotal: this.grandTotal,
      Items: this.Items,
    };
  },
});

然后你可以把它保存到Session：

Then you can save it to Session:

Session.set('shoppingCart', cart.toJSON());

并恢复：

ShoppingCart.fromJSON(Session.get('shoppingCart'));

这篇关于流星在会话中存储和检索自定义对象的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！