Question

The question

I have an itemview which receives a model through its initializer.
When the itemview gets rendered, attributes are added to the view’s element for each model property.

Why does this happen, and how can I prevent this?

Example scenario

A simplified example of the code I have looks as follows:

var MyView = Marionette.ItemView.extend({
  tagName: 'div',
  id: 'myView',
  className: 'myClass',
  template: someTemplate,

  initialize: function(model) {
    this.model = model;
  }
});
var myView = new MyView(someBackboneModel);
myView.render();

Assuming the model has an ‘id’ attribute of value ‘124’, this results in an element like this:

<div id="124" foo="foo" bar="bar" class="myClass">
  <!-- blabla -->
</div>

The problem

As you can see the id value set in the MyView class gets replaced by the id property of the model.

I have other ItemViews in my app which are rendered by a Backbone.Marionette.CollectionView which renders ItemView elements which do not exhibit this behavior and don’t add their model attributes to their $el at all.

Any ideas?

I’ve tried digging around in the Marionette Source and the Backbone source, but so far I can’t find why this happens.

Addendum

At request of Derick Bailey, here’s the full view and template which is causing this problem for me:

The View:

var Admin_Applications_ApplicationReader_Application_View = Marionette.ItemView.extend({
  tagName: "div",
  id: "Admin-Applications-ApplicationReader-Application-View",
  template: ApplicationTemplate,
  templateHelpers: {
    moment: Moment
  },

  initialize: function(model) {
    this.model = model;
    this.bindTo(this, 'layout', this.onLayout);
  },

  // Callbacks
  //----------
  onRender: function() {
    var that = this;
    setTimeout(function() {
      that.onLayout();
      var $scrollContainer = that.$el.find('#Admin-Applications-ApplicationReader-Body'), 
          scrollPane = new ScrollPane($scrollContainer, {
            maxHeightProperty: 'maxHeight',
            scrollUpButton: false,
            scrollDownButton: false
          });
    }, 0);
  },

  // Layout
  //-------
  onLayout: function() {
    var css;

    // Calculate desktop styles
    if ($(window).width() > 767) {
      css = this.calculateBodyStyle();
    }
    else {
      css = {
        applicationBody: { height: 'auto' }
      }
    }

    // apply styles
    this.$el.find('#Admin-Applications-ApplicationReader-Body').css(css.applicationBody);

    // re-initialize scroll-pane
    this.$el.find('.scroll-container').trigger('scroll-pane:new-content');
  },
  calculateBodyStyle: function() {
    var $title = this.$el.find('#Admin-Applications-ApplicationReader-Title'),
        viewHeight = this.$el.height(),
        titleHeight = $title.outerHeight(true),
        bodyHeight = viewHeight - titleHeight,
        css = {
          applicationBody: { maxHeight: bodyHeight },
        };

    return css;
  }
});

The template:

<div id="Admin-Applications-ApplicationReader-Title" class="page-header no-top-margin">
  <h2>Application&nbsp;
    <span class="no-wrap"><small>Package: <%= package %>,&nbsp;</small></span> 
    <span class="no-wrap"><small><%= moment(submission_timestamp, 'YYYY-MM-DD HH:mm:ss').fromNow() %></small></span>
  </h2>
</div>

<div id="Admin-Applications-ApplicationReader-Body" class="container-white scroll-container">
  <ul class="application unstyled scroll-content">
    <li class="section summary-section">
      <div class="section-header">
        <h3>Summary</h3>
      </div>

      <table class="section-body no-border table-condensed">
        <tbody>
          <tr>
            <th>Package:</th>
            <td><%= package %></td>
          </tr>
          <tr>
            <th>Date of last flight:</th>
            <td><%= date_of_last_flight %></td>
          </tr>
          <tr>
            <th>Date of renewel:</th>
            <td><%= date_of_ir_renewel %></td>
          </tr>
        </tbody>
      </table>
    </li>
    <!-- /.summary-section -->

    <li class="section credentials-section">
      <div class="section-header">
        <h3>Credentials</h3>
      </div>

      <table class="section-body no-border table-condensed">
        <tbody>
          <tr>
            <th>Pilot Training Institute:</th>
            <td><%= pilot_training_institute %></td>
          </tr>
          <tr>
            <th>Date of exam:</th>
            <td><%= moment(date_of_exam).format('DD-MM-YYYY') %></td>
          </tr>
          <tr>
            <th>Date of last flight:</th>
            <td><%= moment(date_of_last_flight).format('DD-MM-YYYY') %></td>
          </tr>
          <tr>
            <th>Date of MCC Certificate:</th>
            <td><%= moment(date_of_mcc_certificate).format('DD-MM-YYYY') %></td>
          </tr>
          <tr>
            <th>Date of renewel:</th>
            <td><%= moment(date_of_ir_renewel).format('DD-MM-YYYY') %></td>
          </tr>
        </tbody>
      </table>
    </li>
    <!-- /.credentials-section -->

    <li class="section personal-information-section">
      <div class="section-header">
        <h3>Personal information</h3>
      </div>

      <table class="section-body no-border table-condensed">
        <tbody>
          <tr>
            <th>Name:</th>
            <td><%= [first_name, last_name].join(' ') %></td>
          </tr>
          <tr>
            <th>Adress:</th>
            <td><%= address %></td>
          </tr>
          <tr>
            <th>Zip code:</th>
            <td><%= zip_code %></td>
          </tr>
          <tr>
            <th>City:</th>
            <td><%= city %></td>
          </tr>
          <tr>
            <th>Country:</th>
            <td><%= country %></td>
          </tr>
          <tr>
            <th>Language:</th>
            <td><%= language %></td>
          </tr>
          <tr>
            <th>Telephone:</th>
            <td><%= telephone %></td>
          </tr>
          <tr>
            <th>Celĺphone:</th>
            <td><%= cell_phone %></td>
          </tr>
          <tr>
            <th>E-mail:</th>
            <td><%= email %></td>
          </tr>
          <tr>
            <th>Date of birth:</th>
            <td><%= moment(date_of_birth).format('DD-MM-YYYY') %></td>
          </tr>
        </tbody>
      </table>        
    </li>
    <!-- /.personal-information-section -->
  </ul>
  <!-- /.application.scroll-content -->
</div>

Answer 1

The problem is how you’re passing the model into the view upon instantiation. You should instantiate the view like this:

var myView = new MyView({model: someBackboneModel});

And you can remove the this.model = model code from the initialize method — Backbone sets this for you when you specify a model option in the constructor.

The reason your view element has additional attributes is that model.attributes is being set as the optional attributes parameter of your view. The attributes are added when your element is rendered. To properly use this, you would instantiate like:

var myView = new MyView({
    model: someBackboneModel,
    attributes: { id: ..., class: ..., data-foo: bar }
})