在对象数组中编辑对象的属性

Question

I have a class itemCollection that stores information about purchases. This class has array _items as property where purchases are stores. When user adds new purchase in cart this class using addItem method that adds that item in _items property if its already has this item this method iterates quantity property if not adds new item in array.

Problem is that instead of adding new item in array when other item is chosen its keeps incrementing quantity property of a first item that was added.

cartCollection class (object):

var cartCollection = {
    _items: [],
    addItem: function(obj) {
      'use strict';
      var purchase = {
        item: {
          id: obj.id,
          name: obj.name,
          price: obj.price
        },
        thisItemTotal: obj.price,
        quantity: 1
      };
      var result = _.findWhere(this._items, purchase.item.id);
      console.log(result);
      if (typeof result != 'undefined') {
        //console.log(result);
        var index = _.findIndex(this._items, {
          id: result.item.id
        });
        //console.log(index);
        result.quantity++;
        this._items[index] = result;
        this._itemTotalPrice();
      } else if (typeof result === 'undefined') {
        console.log("Im was called!");
        this._items.push(purchase);
        console.log(this._items);
      }
    },
    ...

Answer 1

Since purchase doesn't have an ID, but has an "item" with an ID, The correct find statement should be:

var result = _.find(this._items, function(item) {
   return item.item.id == purchase.item.id;
});

It might be better to rename _items to _purchases in order to disambiguate

The complete code should be something like:

addItem: function(obj) {
  'use strict';
  var purchase = {
    item: _.pick(obj, 'id', 'name', 'price')
    thisItemTotal: obj.price,
    quantity: 1
  };

  var result = _.find(this._items, function(item) {
    return item.item.id == purchase.item.id;
  });

  console.log(result);

  if (result) {
    result.quantity++;
    this._itemTotalPrice();
  }
  else {
    console.log("Im was called!");
    this._items.push(purchase);
    console.log(this._items);
  }
},

Answer 2

Your findWhere statement is broken. It should be:

var result = _.findWhere(this._items, {id:purchase.item.id});

Good luck