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FetchableMixin

Makes the calls to the fetch method more robust by:

  • preventing multiple server calls when the fetch is called quickly one call after another
  • setting the reset option automatically to optimize collections loading (if requested)
  • checking, if the model has already been fetched and ensuring, that a model has always been fetched before it is used

Remarks​

This mixin overrides the fetch method and calls the original implementation from it. If you supply your own custom implementation of this method, or use another mixin which overrides it, you should apply this mixin after yours.

When the fetch method is called and the previous call has not ended yet, the new call will not be made. The promise returned by the previous call will be returned instead. If you specified different options than for the previous call, they will not be reflected.

How to apply the mixin to a collection​

var MyCollection = Backbone.Collection.extend({

  constructor: function MyCollection(models, options) {
    Backbone.Collection.prototype.constructor.apply(this, arguments);
    this
      .makeConnectable(options)
      .makeFetchable(options);
  }
  
});

ConnectableMixin.mixin(MyCollection.prototype);
FetchableMixin.mixin(MyCollection.prototype);

This mixin us usually combined together with the ConnectableMixin or with another cumulated mixin which includes it.

How use the mixin​

// Set the `reset` option for the future `fetch` calls automatically
var collection = new MyCollection(undefined, {
      connector: connector,
      autoreset: true
    });
collection.fetch();

// Ensure that the collection has been fetched and process it (I)
collection
  .ensureFetched()
  .done(function () {
    ...
  });

makeFetchable(options) : this​

Must be called in the constructor to initialize the mixin functionality. Expects the Backbone.Model or Backbone.Collection constructor options passed in.

Recognized option properies:

autoreset : If set to true, the reset option for the future fetch calls will be set to true automatically, unless this option is not set by the caller (boolean, undefined by default)

fetching​

Can be checked to test whether the model or collection is currently being fetched. When fetching is in progress, it contains the promise returned by the most recent fetch call. When no fetching is in proress it is false. (promise or boolean, read-only)

fetched​

Can be checked to test whether the most recent fetch call has succeeded or not on this model or collection; it is set to true on the first occurrence and never changed afterwards (boolean, read-only)

error​

Contains an error if the most recent fetch call failed. It is undefined if the most recent fetch call succeeded (Error, read-only)

ensureFetched(options) : promise​

Returns a promise resolved as soon as the model is fetched. It fetches the model, if it has not been fetched yet, or it returns immediately, when the model has already been fetched.

invalidateFetch​

Invalidates the fetched state of the collection so that the next ensureFetched() call will fetch the data.

See Also​

ConnectableMixin, ResourceMixin