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Marionette.View

Marionette has a base Marionette.View type that other views extend from. This base view provides some common and core functionality for other views to take advantage of.

Note: The Marionette.View type is not intended to be used directly. It exists as a base view for other view types to be extended from, and to provide a common location for behaviors that are shared across all views.

Documentation Index

Binding To View Events

Marionette.View extends Marionette.BindTo. It is recommended that you use the bindTo method to bind model, collection, or other events from Backbone and Marionette objects.

MyView = Backbone.Marionette.ItemView.extend({
  initialize: function(){
    this.bindTo(this.model, "change:foo", this.modelChanged);
    this.bindTo(this.collection, "add", this.modelAdded);
  },

  modelChanged: function(model, value){
  },

  modelAdded: function(model){
  }
});

The context (this) will automatically be set to the view. You can optionally set the context by passing in the context object as the 4th parameter of bindTo.

ItemView close

View implements a close method, which is called by the region managers automatically. As part of the implementation, the following are performed:

  • unbind all bindTo events
  • unbind all custom view events
  • unbind all DOM events
  • remove this.el from the DOM
  • call an onClose event on the view, if one is provided

By providing an onClose event in your view definition, you can run custom code for your view that is fired after your view has been closed and cleaned up. This lets you handle any additional clean up code without having to override the close method.

Backbone.Marionette.ItemView.extend({
  onClose: function(){
    // custom cleanup or closing code, here
  }
});

View.triggers

Views can define a set of triggers as a hash, which will convert a DOM event in to a view.trigger event.

The left side of the hash is a standard Backbone.View DOM event configuration, while the right side of the hash is the view event that you want to trigger from the view.

MyView = Backbone.Marionette.ItemView.extend({
  // ...

  triggers: {
    "click .do-something": "something:do:it"
  }
});

view = new MyView();
view.render();

view.on("something:do:it", function(){
  alert("I DID IT!");
});

// "click" the 'do-something' DOM element to 
// demonstrate the DOM event conversion
view.$(".do-something").trigger("click");

The result of this is an alert box that says, "I DID IT!"

You can also specify the triggers as a function that returns a hash of trigger configurations

Backbone.Marionette.CompositeView.extend({
  triggers: function(){
    return {
      "click .that-thing": "that:i:sent:you"
    };
  }
});

Triggers work with all View types that extend from the base Marionette.View.

View.modelEvents and View.collectionEvents

Similar to the events hash, views can specify a configuration hash for collections and models. The left side is the event on the model or collection, and the right side is the name of the method on the view.

Backbone.Marionette.CompositeView.extend({

  modelEvents: {
    "change:name": "nameChanged" // equivalent to view.bindTo(view.model, "change:name", view.nameChanged, view)
  },

  collectionEvents: {
    "add": "itemAdded" // equivalent to view.bindTo(view.collection, "add", collection.itemAdded, view)
  },

  // ... event handler methods
  nameChanged: function(){ /* ... */ },
  itemAdded: function(){ /* ... */ },

})

These will use the memory safe bindTo, and will set the context (the value of this) in the handler to be the view. Events are bound at the time of instantiation instanciation, and an exception will be thrown if the handlers on the view do not exist.

View.serializeData

The serializeData method will serialize a view's model or collection - with precedence given to collections. That is, if you have both a collection and a model in a view, calling the serializeData method will return the serialized collection.

View.bindUIElements

In several cases you need to access ui elements inside the view to retrieve their data or manipulate them. For example you have a certain div element you need to show/hide based on some state, or other ui element that you wish to set a css class to it. Instead of having jQuery selectors hanging around in the view's code you can define a ui hash that contains a mapping between the ui element's name and its jQuery selector. Afterwards you can simply access it via this.ui.elementName. See ItemView documentation for examples.

This functionality is provided via the bindUIElements method. Since View doesn't implement the render method, then if you directly extend from View you will need to invoke this method from your render method. In ItemView and CompositeView this is already taken care of.

View.templateHelpers

There are times when a view's template needs to have some logic in it, and the view engine itself will not provide an easy way to accomplish this. For example, Underscore templates do not provide a helper method mechanism while Handlebars templates do.

A templateHelpers attribute can be applied to any View object that renders a template. When this attribute is present, it's contents will be mixed in to the data object that comes back from the serializeData method. This will allow you to create helper methods that can be called from within your templates.

Basic Example

<script id="my-template" type="text/html">
  I think that <%= showMessage() %>
</script>
MyView = Backbone.Marionette.ItemView.extend({
  template: "#my-template",

  templateHelpers: {
    showMessage: function(){
      return this.name + " is the coolest!"
    }
  }

});

model = new Backbone.Model({name: "Backbone.Marionette"});
view = new MyView({
  model: model
});

view.render(); //=> "I think that Backbone.Marionette is the coolest!";

Accessing Data Within The Helpers

In order to access data from within the helper methods, you need to prefix the data you need with this. Doing that will give you all of the methods and attributes of the serialized data object, including the other helper methods.

templateHelpers: {
  something: function(){
    return "Do stuff with " + this.name + " because it's awesome.";
  }
}

Object Or Function As templateHelpers

You can specify an object literal (as shown above), a reference to an object literal, or a function as the templateHelpers.

If you specify a function, the function will be invoked with the current view instance as the context of the function. The function must return an object that can be mixed in to the data for the view.

Backbone.Marionette.ItemView.extend({
  templateHelpers: function(){
    return {
      foo: function(){ /* ... */ }
    }
  }
});

Change Which Template Is Rendered For A View

There may be some cases where you need to change the template that is used for a view, based on some simple logic such as the value of a specific attribute in the view's model. To do this, you can provide a getTemplate function on your views and use this to return the template that you need.

MyView = Backbone.Marionette.ItemView.extend({
  getTemplate: function(){
    if (this.model.get("foo")){
      return "#some-template";
    } else {
      return "#a-different-template";
    }
  }
});

This applies to all view types.

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