Edit property of an object in array of objects

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);
      }
    },
    ...

I know, this is habit after other languages

qr11
– qr11

2015-06-02 20:21:24 +00:00
Commented Jun 2, 2015 at 20:21 — qr11
– qr11, Commented Jun 2, 2015 at 20:21

u.k · Accepted Answer · 2015-06-03 03:14:13Z

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);
  }
},

edited Jun 3, 2015 at 3:14

answered Jun 3, 2015 at 2:58

u.k

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Comments

Lodewijk Bogaards · Accepted Answer · 2015-06-02 20:23:47Z

0

Your findWhere statement is broken. It should be:

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

Good luck

answered Jun 2, 2015 at 20:23

Lodewijk Bogaards

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4 Comments

qr11 Over a year ago

Now it adds new object but not increments quantity.

Lodewijk Bogaards Over a year ago

you're pushing purchase instead of purchase.item

qr11 Over a year ago

Did I understood you correctly I'm need to use it like this: this._items.push(purchase.item);? If that so now im getting: Uncaught TypeError: Cannot read property 'id' of undefined

Lodewijk Bogaards Over a year ago

it's pretty impossible to answer your questions without all the context. I am going to leave it at this and wish you good luck.

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