Error occurred while trying to fetch the Backbone.js collection due to undefined value of 'this._byId'

Question

Error occurred while trying to fetch the Backbone.js collection due to undefined value of 'this._byId'

I am currently working with coffeescript and my code is quite straightforward:

class SomeCollection extends Backbone.Collection
  constructor: (@options) ->
  url: ->
    "#{$SCRIPT_ROOT}/some/data/#{@options.someId}"
  model: SomeModel

class SomeView extends Backbone.View
  initialize: ->
    myCollection = new SomeCollection()
    myCollection.fetch
      success: (coll, resp) ->
        console.log coll

The response JSON from the collection's URL looks like this:

[{"id": 1, "comments": "", "name": "images/exceptions/59.png"}]

However, even before anything gets printed to the console, I encounter a backbone.js error at line 768: Cannot read property 1 of undefined. The undefined object in this case is this._byId within the collection's get function. How can I troubleshoot this issue?

javascript backbone.js collections coffeescript fetch

Answer 1

Answer №1

When extending Backbone.Collection and creating your own constructor, it's important to remember to call the parent constructor.

constructor: (@options) ->
  super null, @options

Typically, a Collection takes arguments in the form of (models, options), so sticking with that format is recommended.

constructor: (models, @options) ->
  super models, @options

Alternatively, using initialize instead of

constructor</code can help avoid any potential issues.</p>

<pre><code>initialize: (models, @options) ->

Answer 2

When extending Backbone.Collection and creating your own constructor, it's important to remember to call the parent constructor.

constructor: (@options) ->
  super null, @options

Typically, a Collection takes arguments in the form of (models, options), so sticking with that format is recommended.

constructor: (models, @options) ->
  super models, @options

Alternatively, using initialize instead of

constructor</code can help avoid any potential issues.</p>

<pre><code>initialize: (models, @options) ->

Error occurred while trying to fetch the Backbone.js collection due to undefined value of 'this._byId'

Answer №1

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