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Advanced NextCollectionView Usage

NextCollectionView provides a lot of possibilities to sort, filter and manages children.

Documentation Index

NextCollectionView's children

The NextCollectionView can store and manage its child views. This allows you to easily access the views within the collection view, iterate them, find them by a given indexer such as the view's model or collection, and more.

NextCollectionView's buildChildView

The buildChildView is responsible for taking the ChildView class and instantiating it with the appropriate data. This method takes three parameters and returns a view instance to be used as thechild view.

buildChildView: function(child, ChildViewClass, childViewOptions){
  // build the final list of options for the childView class
  var options = _.extend({model: child}, childViewOptions);
  // create the child view instance
  var view = new ChildViewClass(options);
  // return it
  return view;
},

Override this method when you need a more complicated build, but use childView if you need to determine which View class to instantiate.

var Bb = require('backbone');
var Mn = require('backbone.marionette');

var MyNextCollectionView = Mn.NextCollectionView.extend({
  childView: function(child) {
    if (child.get('type') === 'list') {
      return MyListView;
    }

    return MyView;
  },
  buildChildView: function(child, ChildViewClass, childViewOptions) {
    var options = {};

    if (child.get('type') === 'list') {
      var childList = new Bb.Collection(child.get('list'));
      options = _.extend({collection: childList}, childViewOptions);
    } else {
      options = _.extend({model: child}, childViewOptions);
    }

    // create the child view instance
    var view = new ChildViewClass(options);
    // return it
    return view;
  }

});

NextCollectionView's addChildView

The addChildView method can be used to add a view that is independent of your Backbone.Collection. Note that this added view will be subject to filtering and ordering and may be difficult to manage in complex situations. Use with care.

This method takes two parameters, the child view instance and the index for where it should be placed within the NextCollectionView's children. It returns the added view.

var Mn = require('backbone.marionette');
var buttonView = new ButtonView();
var MyCollectionView = Mn.NextCollectionView.extend({
  onRender: function() {
    this.addChildView(buttonView, this.collection.length);
  }
});

var myCollectionView = new MyCollectionView();

myCollectionView.render();

NextCollectionView: Retrieve Child Views

You can retrieve a view by any of the index. If the findBy* method cannot find the view, it will return undefined.

NextCollectionView children's: findByCid

Find a view by it's cid.

var bView = myCollectionView.children.findByCid(buttonView.cid);

NextCollectionView children's: findByModel

Find a view by model.

var bView = myCollectionView.children.findByModel(buttonView.model);

NextCollectionView children's: findByModelCid

Find a view by model cid.

var bView = myCollectionView.children.findByModelCid(buttonView.model.cid);

NextCollectionView children's: findByIndex

Find by numeric index (unstable)

var bView = myCollectionView.children.findByIndex(0);

NextCollectionView children's: findIndexByView

Find the index of the view inside the children

var index = myCollectionView.children.findIndexByView(bView);

NextCollectionView's removeChildView

The removeChildView method is useful if you need to remove and destroy a view from the NextCollectionView without affecting the view's collection. In most cases it is better to use the data to determine what the NextCollectionView should display.

This method accepts the child view instance to remove as its parameter. It returns the removed view;

var Mn = require('backbone.marionette');

Mn.NextCollectionView.extend({
  onChildViewClose: function(childView, model) {
    // NOTE: we must wait for the server to confirm
    // the destroy PRIOR to removing it from the collection
    model.destroy({wait: true});

    // but go ahead and remove it visually
    this.removeChildView(childView);
  }
});

NextCollectionView's detachChildView

This method is the same as removeChildView with the exception that the removed view is not destroyed.

NextCollectionView's swapChildViews

Swap the location of two views in the NextCollectionView children and in the el. This can be useful when sorting is arbitrary or is not performant.

If either of the two views aren't part of the NextCollectionView an error will be thrown.

If one child is in the el but the other is not, filter will be called.

var Mn = require('backbone.marionette');

var collection = new Backbone.Collection([
  { name: 'first' },
  { name: 'middle' },
  { name: 'last' }
]);

var myCollection = new Mn.NextCollectionView({
  collection: collection,
  childView: MyChildView
});

myCollection.swapChildViews(myCollection.children.first(), myCollection.children.last());

myCollection.children.first().model.get('name'); // "last"
myCollection.children.last().model.get('name'); // "first"

NextCollectionView childView Iterators And Collection Functions

The container object borrows several functions from Underscore.js, to provide iterators and other collection functions, including:

These methods can be called directly on the container, to iterate and process the views held by the container.

var Bb = require('backbone');
var Mn = require('backbone.marionette');

var collectionView = new Mn.NextCollectionView({
  collection: new Bb.Collection()
});

collectionView.render();

// iterate over all of the views and process them
collectionView.children.each(function(childView) {
  // process the `childView` here
});

NextCollectionView's filter

The filter method will loop through the NextCollectionView children and test them against the viewFilter. The views that pass the viewFilterare rendered if necessary and attached to the CollectionView and the views that are filtered out will be detached. If a viewFilter exists the before:filter and filter events will be triggered. By default the NextCollectionView will refilter when views change or when the NextCollectionView is sorted.

NextCollectionView's viewFilter

NextCollectionView allows for a custom viewFilter option if you want to prevent some of the underlying children from being attached to the DOM. A viewFilter can be a function, predicate object. or string.

NextCollectionView's viewFilter as a function

The viewFilter function takes a view from the children and returns a truthy value if the child should be attached, and a falsey value if it should not.

var Bb = require('backbone');
var Mn = require('backbone.marionette');

var cv = new Mn.NextCollectionView({
  childView: SomeChildView,
  emptyView: SomeEmptyView,
  collection: new Bb.Collection([
    { value: 1 },
    { value: 2 },
    { value: 3 },
    { value: 4 }
  ]),

  // Only show views with even values
  viewFilter: function (view, index, children) {
    return view.model.get('value') % 2 === 0;
  }
});

// renders the views with values '2' and '4'
cv.render();

NextCollectionView's viewFilter as a predicate object

The viewFilter predicate object will filter against the view's model attributes.

var Bb = require('backbone');
var Mn = require('backbone.marionette');

var cv = new Mn.NextCollectionView({
  childView: SomeChildView,
  emptyView: SomeEmptyView,
  collection: new Bb.Collection([
    { value: 1 },
    { value: 2 },
    { value: 3 },
    { value: 4 }
  ]),

  // Only show views with even values
  viewFilter: { value: 2 }
});

// renders the view with values '2'
cv.render();

NextCollectionView's viewFilter as a predicate object

The viewFilter string represents the view's model attribute and will filter truthy values.

var Bb = require('backbone');
var Mn = require('backbone.marionette');

var cv = new Mn.NextCollectionView({
  childView: SomeChildView,
  emptyView: SomeEmptyView,
  collection: new Bb.Collection([
    { value: 0 },
    { value: 1 },
    { value: 2 },
    { value: null },
    { value: 4 }
  ]),

   // Only show views 1,2, and 4
  viewFilter: 'value'
});

// renders the view with values '2'
cv.render();

NextCollectionView's getFilter

Override this function to programatically decide which viewFilter to use when filter is called.

var Mn = require('backbone.marionette');

var MyCollectionView = Mn.NextCollectionView.extend({
  summaryFilter: function(view) {
    return view.model.get('type') === 'summary';
  },
  getFilter: function() {
    if(this.collection.length > 100) {
      return this.summaryFilter;
    }
    return this.viewFilter;
  }
});

NextCollectionView's setFilter

The setFilter method modifies the NextCollectionView's viewFilter attribute and filters. Passing { preventRender: true } in the options argument will prevent the view being rendered.

var Mn = require('backbone.marionette');

var cv = new Mn.NextCollectionView({
  collection: someCollection
});

cv.render();

var newFilter = function(view, index, children) {
  return view.model.get('value') % 2 === 0;
};

// Note: the setFilter is preventing the automatic re-render
cv.setFilter(newFilter, { preventRender: true });

//Render the new state of the ChildViews instead of the whole DOM.
cv.render();

NextCollectionView's removeFilter

This function is actually an alias of setFilter(null, options). It is useful for removing filters. removeFilter also accepts preventRender as a option.

var Mn = require('backbone.marionette');

var cv = new Mn.NextCollectionView({
  collection: someCollection
});

cv.render();

cv.setFilter(function(view, index, children) {
  return view.model.get('value') % 2 === 0;
});

//Remove the current filter without rendering again.
cv.removeFilter({ preventRender: true });

NextCollectionView's sort

The sort method will loop through the NextCollectionView children and sort them with the viewComparator. By default, if a viewComparator is not set, the NextCollectionView will sort the views by the order of the models in the collection. If set to false view sorting will be disabled. This method is also triggered internally when rendering and before:sort and sort events will be triggered before and after sorting.

By default the NextCollectionView will maintain a sorted collection's order in the DOM. This behavior can be disabled by specifying {sortWithCollection: false} on initialize.

NextCollectionView's viewComparator

NextCollectionView allows for a custom viewComparator option if you want your NextCollectionView's children to be rendered with a different sort order than the underlying Backbone collection uses.

var Mn = require('backbone.marionette');

var cv = new Mn.NextCollectionView({
  collection: someCollection,
  viewComparator: 'otherFieldToSortOn'
});

var Bb = require('backbone');
var Mn = require('backbone.marionette');

var myCollection = new Bb.Collection([
  { id: 1 },
  { id: 4 },
  { id: 3 },
  { id: 2 }
]);

myCollection.comparator = 'id';

var mySortedColView = new Mn.NextCollectionView({
  //...
  collection: myCollection
});

var myUnsortedColView = new Mn.NextCollectionView({
  //...
  collection: myCollection,
  sort: false
});

mySortedColView.render(); // 1 4 3 2
myUnsortedColView.render(); // 1 4 3 2

// mySortedColView auto-renders 1 2 3 4
// myUnsortedColView has no change
myCollection.sort();

The viewComparator can take any of the acceptable Backbone.Collection comparator formats -- a sortBy (pass a function that takes a single argument), as a sort (pass a comparator function that expects two arguments), or as a string indicating the attribute to sort by.

NextCollectionView's getComparator

Override this method to determine which viewComparator to use.

var Mn = require('backbone.marionette');

var MyCollectionView = Mn.NextCollectionView.extend({
  sortAsc: function(model) {
    return -model.get('order');
  },
  sortDesc: function(model) {
    return model.get('order');
  },
  getComparator: function() {
    // The collectionView's model
    if (this.model.get('sorted') === 'ASC') {
      return this.sortAsc;
    }

    return this.sortDesc;
  }
});

NextCollectionView's setComparator

The setComparator method modifies the NextCollectionView's viewComparator attribute and re-sorts. Passing { preventRender: true } in the options argument will prevent the view being rendered.

var Mn = require('backbone.marionette');

var cv = new Mn.NextCollectionView({
  collection: someCollection
});

cv.render();

// Note: the setComparator is preventing the automatic re-render
cv.setComparator('orderBy', { preventRender: true });

// Render the children ordered by the orderBy attribute
cv.render();

NextCollectionView's removeComparator

This function is actually an alias of setComparator(null, options). It is useful for removing the comparator. removeComparator also accepts preventRender as a option.

var Mn = require('backbone.marionette');

var cv = new Mn.NextCollectionView({
  collection: someCollection
});

cv.render();

cv.setComparator('orderBy');

//Remove the current comparator without rendering again.
cv.removeComparator({ preventRender: true });

NextCollectionView's sortWithCollection

By default the NextCollectionView will maintain a sorted collection's order in the DOM. This behavior can be disabled by specifying {sortWithCollection: false} on initialize or on the view definiton

var Bb = require('backbone');
var Mn = require('backbone.marionette');

var myCollection = new Bb.Collection([
  { id: 1 },
  { id: 4 },
  { id: 3 },
  { id: 2 }
]);

myCollection.comparator = 'id';

var mySortedColView = new Mn.NextCollectionView({
  //...
  collection: myCollection
});

var myUnsortedColView = new Mn.NextCollectionView({
  //...
  collection: myCollection,
  sortWithCollection: false
});

mySortedColView.render(); // 1 4 3 2
myUnsortedColView.render(); // 1 4 3 2

// mySortedColView auto-renders 1 2 3 4
// myUnsortedColView has no change
myCollection.sort();

Binding ui

By default, NextCollectionView will not bind the ui object. As it has no direct template of its own to manage, this isn't usually an issue. There may be instances where binding ui is helpful when you want to access elements inside NextCollectionViews children with getUI().

If you need to bind ui yourself, you can just run bindUIElements on the collection:

var Mn = require('backbone.marionette');

var MyCollectionView = Mn.NextCollectionView.extend({
  ...

  ui: {
    checkbox: 'input[type="checkbox"]'
  }
});

var collectionView = new MyCollectionView();

collectionView.bindUIElements();

console.log(collectionView.getUI('checkbox')); // Output all checkboxes.
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