Marionette.CollectionView
The CollectionView
will loop through all of the models in the specified collection, render each of them using a specified childView
, then append the results of the child view's el
to the collection view's el
. By default the CollectionView
will maintain a sorted collection's order in the DOM. This behavior can be disabled by specifying {sort: false}
on initialize.
CollectionView extends directly from Marionette.View. Please see the Marionette.View documentation for more information on available features and functionality.
Additionally, interactions with Marionette.Region will provide features such as onShow
callbacks, etc. Please see the Region documentation for more information.
Documentation Index
-
CollectionView's
childView
-
CollectionView's
emptyView
- Callback Methods
-
CollectionView Events
- "before:render" event
- "render" event
- "before:reorder" / "reorder" event
- "before:destroy" event
- "destroy" / "destroy:collection" event
- "before:add:child" / "add:child" event
- "before:remove:child event
- "remove:child" event
- "childview:*" event bubbling from child views
- "before:render:collection" event
- "render:collection" event
- CollectionView Child View Events
- CollectionView render
- CollectionView: Automatic Rendering
- CollectionView: Re-render Collection
- CollectionView's attachHtml
- CollectionView's resortView
- CollectionView's viewComparator
- CollectionView's
filter
- CollectionView's children
- CollectionView destroy
CollectionView's childView
Specify a childView
in your collection view definition. This must be a Backbone view object definition, not an instance. It can be any Backbone.View
or be derived from Marionette.ItemView
.
var MyChildView = Marionette.ItemView.extend({});
Marionette.CollectionView.extend({
childView: MyChildView
});
Child views must be defined before they are referenced by the childView
attribute in a collection view definition. Use getChildView
to lookup the definition as child views are instantiated.
Alternatively, you can specify a childView
in the options for the constructor:
var MyCollectionView = Marionette.CollectionView.extend({...});
new MyCollectionView({
childView: MyChildView
});
If you do not specify a childView
, an exception will be thrown stating that you must specify a childView
.
CollectionView's getChildView
The value returned by this method is the ChildView
class that will be instantiated when a Model
needs to be initially rendered. This method also gives you the ability to customize per Model
ChildViews
.
var FooBar = Backbone.Model.extend({
defaults: {
isFoo: false
}
});
var FooView = Marionette.ItemView.extend({
template: '#foo-template'
});
var BarView = Marionette.ItemView.extend({
template: '#bar-template'
});
var MyCollectionView = Marionette.CollectionView.extend({
getChildView: function(item) {
// Choose which view class to render,
// depending on the properties of the item model
if (item.get('isFoo')) {
return FooView;
}
else {
return BarView;
}
}
});
var collectionView = new MyCollectionView({
collection: new Backbone.Collection()
});
var foo = new FooBar({
isFoo: true
});
var bar = new FooBar({
isFoo: false
});
// Renders a FooView
collectionView.collection.add(foo);
// Renders a BarView
collectionView.collection.add(bar);
CollectionView's childViewOptions
There may be scenarios where you need to pass data from your parent collection view in to each of the childView instances. To do this, provide a childViewOptions
definition on your collection view as an object literal. This will be passed to the constructor of your childView as part of the options
.
var ChildView = Marionette.ItemView.extend({
initialize: function(options) {
console.log(options.foo); // => "bar"
}
});
var CollectionView = Marionette.CollectionView.extend({
childView: ChildView,
childViewOptions: {
foo: "bar"
}
});
You can also specify the childViewOptions
as a function, if you need to calculate the values to return at runtime. The model will be passed into the function should you need access to it when calculating childViewOptions
. The function must return an object, and the attributes of the object will be copied to the childView
instance's options.
var CollectionView = Marionette.CollectionView.extend({
childViewOptions: function(model, index) {
// do some calculations based on the model
return {
foo: "bar",
childIndex: index
}
}
});
CollectionView's childViewEventPrefix
You can customize the event prefix for events that are forwarded through the collection view. To do this, set the childViewEventPrefix
on the collection view. For more information on the childViewEventPrefix
see "childview:*" event bubbling from child views
var CV = Marionette.CollectionView.extend({
childViewEventPrefix: "some:prefix"
});
var c = new CV({
collection: myCol
});
c.on("some:prefix:render", function(){
// child view was rendered
});
c.render();
The childViewEventPrefix
can be provided in the view definition or in the constructor function call, to get a view instance.
CollectionView's childEvents
A childEvents
hash or method permits handling of child view events without manually setting bindings. The values of the hash can either be a function or a string method name on the collection view.
// childEvents can be specified as a hash...
var MyCollectionView = Marionette.CollectionView.extend({
childEvents: {
// This callback will be called whenever a child is rendered or emits a `render` event
render: function() {
console.log('A child view has been rendered.');
}
}
});
// ...or as a function that returns a hash.
var MyCollectionView = Marionette.CollectionView.extend({
childEvents: function() {
return {
render: this.onChildRendered
}
},
onChildRendered: function () {
console.log('A child view has been rendered.');
}
});
childEvents
also catches custom events fired by a child view. Take note that the first argument to a childEvents
handler is the child view itself.
// The child view fires a custom event, `show:message`
var ChildView = Marionette.ItemView.extend({
// Events hash defines local event handlers that in turn may call `triggerMethod`.
events: {
'click .button': 'onClickButton'
},
// Triggers hash converts DOM events directly to view events catchable on the parent.
triggers: {
'submit form': 'submit:form'
},
onClickButton: function () {
// Both `trigger` and `triggerMethod` events will be caught by parent.
this.trigger('show:message', 'foo');
this.triggerMethod('show:message', 'bar');
}
});
// The parent uses childEvents to catch the child view's custom event
var ParentView = Marionette.CollectionView.extend({
childView: ChildView,
childEvents: {
'show:message': 'onChildShowMessage',
'submit:form': 'onChildSubmitForm'
},
onChildShowMessage: function (childView, message) {
console.log('A child view fired show:message with ' + message);
},
onChildSubmitForm: function (childView) {
console.log('A child view fired submit:form');
}
});
CollectionView's buildChildView
When a custom view instance needs to be created for the childView
that represents a child, override the buildChildView
method. This method takes three parameters and returns a view instance to be used as the child 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;
},
CollectionView's removeChildView
Remove a specific view instance and destroy it. This function also updates the indices of later views in the collection in order to keep the children in sync with the collection.
// add some views to a CollectionView
var myCollectionView = new MyCollectionView({
collection: new Backbone.Collection([fooModel, barModel]);
});
myCollectionView.render();
var myView = myCollectionView.children.findByModel(foo);
// remove a child view myView
myCollectionView.removeChildView(myView);
// check if the removed view still exist
console.log(myCollectionView.children.findByModel(fooModel)); // return undefined
console.log(myCollectionView.children.findByModel(barModel)); // return a childView bar
CollectionView's addChild
The addChild
method is responsible for rendering the childViews
and adding them to the HTML for the collectionView
instance. It is also responsible for triggering the events per ChildView
. In most cases you should not override this method. However if you do want to short circuit this method, it can be accomplished via the following.
Marionette.CollectionView.extend({
addChild: function(child, ChildView, index){
if (child.shouldBeShown()) {
Marionette.CollectionView.prototype.addChild.apply(this, arguments);
}
}
});
CollectionView's reorderOnSort
This option is useful when you have performance issues when you resort your CollectionView
. Without this option, your CollectionView
will be completely re-rendered, which can be costly if you have a large number of elements or if your ChildView
s are complex. If this option is activated, when you sort your Collection
, there will be no re-rendering, only the DOM nodes will be reordered. This can be a problem if your ChildView
s use their collection's index in their rendering. In this case, you cannot use this option as you need to re-render each ChildView
.
If you combine this option with a filter that changes the views that are to be displayed, reorderOnSort
will be bypassed to render new children and remove those that are rejected by the filter.
CollectionView's emptyView
When a collection has no children, and you need to render a view other than the list of childViews, you can specify an emptyView
attribute on your collection view.
var NoChildrenView = Marionette.ItemView.extend({
template: "#show-no-children-message-template"
});
Marionette.CollectionView.extend({
// ...
emptyView: NoChildrenView
});
CollectionView's getEmptyView
If you need the emptyView
's class chosen dynamically, specify getEmptyView
:
Marionette.CollectionView.extend({
// ...
getEmptyView: function() {
// custom logic
return NoChildrenView;
}
});
CollectionView's isEmpty
If you want to control when the empty view is rendered, you can override isEmpty
:
Marionette.CollectionView.extend({
isEmpty: function(collection) {
// some logic to calculate if the view should be rendered as empty
return someBoolean;
}
});
CollectionView's emptyViewOptions
Similar to childView
and childViewOptions
, there is an emptyViewOptions
property that will be passed to the emptyView
constructor. It can be provided as an object literal or as a function.
If emptyViewOptions
aren't provided the CollectionView will default to passing the childViewOptions
to the emptyView
.
var EmptyView = Marionette.ItemView({
initialize: function(options){
console.log(options.foo); // => "bar"
}
});
var CollectionView = Marionette.CollectionView({
emptyView: EmptyView,
emptyViewOptions: {
foo: "bar"
}
});
CollectionView's destroyChildren
CollectionView
provides a destroyChildren
method that will only destroy it's childViews. This can be useful when you would like to empty your view but keep the data in the collection
. This method takes an optional checkEmpty
parameter, by default it is set to true
, if false
it will disable the call to checkEmpty
and destroyChildren
will not show the emptyView
.
myView.destroyChildren(); // will show emptyView
myView.destroyChildren({checkEmpty: false}); // will not show emptyView
Callback Methods
There are several callback methods that can be provided on a CollectionView
. If they are found, they will be called by the view's base methods. These callback methods are intended to be handled within the view definition directly.
onBeforeRender callback
A onBeforeRender
callback will be called just prior to rendering the collection view.
Marionette.CollectionView.extend({
onBeforeRender: function(){
// do stuff here
}
});
onRender callback
After the view has been rendered, a onRender
method will be called. You can implement this in your view to provide custom code for dealing with the view's el
after it has been rendered:
Marionette.CollectionView.extend({
onRender: function(){
// do stuff here
}
});
onBeforeReorder callback
If reorderOnSort
is set to true
, onBeforeReorder
will be called just prior to reordering the collection view.
Marionette.CollectionView.extend({
onBeforeReorder: function(){
// do stuff here
}
});
onReorder callback
If reorderOnSort
is set to true
, after the view has been reordered, a onReorder
method will be called.
Marionette.CollectionView.extend({
onReorder: function(){
// do stuff here
}
});
onBeforeDestroy callback
This method is called just before destroying the view.
Marionette.CollectionView.extend({
onBeforeDestroy: function(){
// do stuff here
}
});
onDestroy callback
This method is called just after destroying the view.
Marionette.CollectionView.extend({
onDestroy: function(){
// do stuff here
}
});
onBeforeAddChild callback
This callback function allows you to know when a child / child view instance is about to be added to the collection view. It provides access to the view instance for the child that was added.
Marionette.CollectionView.extend({
onBeforeAddChild: function(childView){
// work with the childView instance, here
}
});
onAddChild callback
This callback function allows you to know when a child / child view instance has been added to the collection view. It provides access to the view instance for the child that was added.
Marionette.CollectionView.extend({
onAddChild: function(childView){
// work with the childView instance, here
}
});
onBeforeRemoveChild callback
This callback function allows you to know when a childView
instance is about to be removed from the collectionView
. It provides access to the view instance for the child that was removed.
Marionette.CollectionView.extend({
onBeforeRemoveChild: function(childView){
// work with the childView instance, here
}
});
onRemoveChild callback
This callback function allows you to know when a child / childView instance has been deleted or removed from the collection.
Marionette.CollectionView.extend({
onRemoveChild: function(childView){
// work with the childView instance, here
}
});
CollectionView Events
There are several events that will be triggered during the life of a collection view. Each of these events is called with the Marionette.triggerMethod function, which calls a corresponding "on{EventName}" method on the view instance (see above).
"before:render" event
Triggers just prior to the view being rendered. Also triggered as "before:render:collection" / onBeforeRenderCollection
.
var MyView = Marionette.CollectionView.extend({...});
var myView = new MyView();
myView.on("before:render", function(){
alert("the collection view is about to be rendered");
});
myView.render();
"render" event
A "render:collection" / onRenderCollection
event will also be fired. This allows you to add more than one callback to execute after the view is rendered, and allows parent views and other parts of the application to know that the view was rendered.
var MyView = Marionette.CollectionView.extend({...});
var myView = new MyView();
myView.on("render", function(){
alert("the collection view was rendered!");
});
myView.on("render:collection", function(){
alert("the collection view was rendered!");
});
myView.render();
"before:reorder" / "reorder" events
When reorderOnSort
is set to true
, these events are fired respectfully just prior/just after the reordering of the collection.
var MyView = Marionette.CollectionView.extend({...});
var myCol = new Backbone.Collection({ comparator: ... })
var myView = new MyView({ reorderOnSort: true });
myView.render();
myCol.comparator = function () { return this.get('foo'); };
myView.on("before:reorder", function(){
alert("the collection view is about to be reordered");
});
myView.on("reorder", function(){
alert("the collection view has been reordered following its collection");
});
myCol.sort()
"before:destroy" event
Triggered just before destroying the view. A "before:destroy:collection" / onBeforeDestroyCollection
event will also be fired
var MyView = Marionette.CollectionView.extend({...});
var myView = new MyView();
myView.on("before:destroy:collection", function(){
alert("the collection view is about to be destroyed");
});
myView.destroy();
"destroy" / "destroy:collection" event
Triggered just after destroying the view, both with corresponding method calls.
var MyView = Marionette.CollectionView.extend({...});
var myView = new MyView();
myView.on("destroy:collection", function(){
alert("the collection view is now destroyed");
});
myView.destroy();
"before:add:child" / "add:child" event
The "before:add:child" event and corresponding onBeforeAddChild
method are triggered just after creating a new childView
instance for a child that was added to the collection, but before the view is rendered and added to the DOM.
The "add:child" event and corresponding onAddChild
method are triggered after rendering the view and adding it to the view's DOM element.
var MyCV = Marionette.CollectionView.extend({
// ...
onBeforeAddChild: function(){
// ...
},
onAddChild: function(){
// ...
}
});
var cv = new MyCV({...});
cv.on("before:add:child", function(viewInstance){
// ...
});
cv.on("add:child", function(viewInstance){
// ...
});
"before:remove:child"
This is triggered after the childView instance has been removed from the collection, but before it has been destroyed.
cv.on("before:remove:child", function(childView){
// ...
});
"remove:child" event
Triggered after a childView instance has been destroyed and removed, when its child was deleted or removed from the collection.
cv.on("remove:child", function(viewInstance){
// ...
});
"childview:*" event bubbling from child views
When a child view within a collection view triggers an event, that event will bubble up through the parent collection view with "childview:" prepended to the event name.
That is, if a child view triggers "do:something", the parent collection view will then trigger "childview:do:something".
// set up basic collection
var myModel = new MyModel();
var myCollection = new MyCollection();
myCollection.add(myModel);
var MyItemView = Marionette.ItemView.extend({
triggers: {
'click button': 'do:something'
}
});
// get the collection view in place
var colView = new CollectionView({
collection: myCollection,
childView: MyItemView,
onChildviewDoSomething: function() {
alert("I said, 'do something!'");
}
});
colView.render();
Now, whenever the button inside the attached childView is clicked, an alert box will appear that says: I said, 'do something!'
It's also possible to attach the event manually using the usual view.on('childview:do:something')
.
before:render:collection event
The before:render:collection
event is triggered before the collectionView
's children have been rendered and buffered. It differs from the collectionsView
's before:render
in that it is only emitted if the collection
is not empty.
render:collection event
The render:collection
event is triggered after a collectionView
's children have been rendered and buffered. It differs from the collectionViews
's render
event in that it happens only if the collection
is not empty.
CollectionView Child View Events
The following events are raised on child views during rendering and destruction of child views, which is consistent with the view lifecycle experienced during Region#show
.
-
before:render
/onBeforeRender
- Called before the view is rendered. -
render
/onRender
- Called after the view is rendered, but before it is attached to the DOM. -
before:show
/onBeforeShow
- Called after the view has been rendered, but before it has been bound to the CollectionView. -
before:attach
/onBeforeAttach
- Called before the view is attached to the DOM. This will not fire if the CollectionView itself is not attached. -
attach
/onAttach
- Called after the view is attached to the DOM. This will not fire if the CollectionView itself is not attached. -
show
/onShow
- Called when the view has been rendered and bound to the CollectionView. -
dom:refresh
/onDomRefresh
- Called when the view is both rendered and shown, but only if it is attached to the DOM. This will not fire if the CollectionView itself is not attached. -
before:destroy
/onBeforeDestroy
- Called before destroying a view. -
destroy
/onDestroy
- Called after destroying a view.
Note: render
, destroy
, and dom:refresh
are triggered on pure Backbone Views during child view rendering, but for a complete implementation of these events the Backbone View should fire render
within render()
and destroy
within remove()
as well as set the following flags:
view.supportsRenderLifecycle = true;
view.supportsDestroyLifecycle = true;
CollectionView render
The render
method of the collection view is responsible for rendering the entire collection. It loops through each of the children in the collection and renders them individually as an childView
.
var MyCollectionView = Marionette.CollectionView.extend({...});
// all of the children views will now be rendered.
new MyCollectionView().render();
CollectionView: Automatic Rendering
After the initial render the collection view binds to the "add", "remove" and "reset" events of the collection that is specified.
When the collection for the view is "reset", the view will call render
on itself and re-render the entire collection.
When a model is added to the collection, the collection view will render that one model in to the collection of child views.
When a model is removed from a collection (or destroyed / deleted), the collection view will destroy and remove that model's child view.
When the collection for the view is sorted, the view will automatically re-sort its child views. if the reorderOnSort
option is set it will attempt to reorder the DOM and do this without a full re-render, otherwise it will re-render if the order has changed. Please Note that if you apply a filter to the collection view and the filtered views change during a sort then it will always re-render.
var collection = new Backbone.Collection();
var myChildView = Marionette.View.extend({
template: false
});
var MyCollectionView = Marionette.CollectionView.extend({
childView: myChildView,
collection: collection,
});
var myCollectionView = new MyCollectionView();
// Collection view will not re-render as it has not been rendered
collection.reset([{foo: 'foo'}]);
myCollectionView.render();
// Collection view will re-render displaying the new model
collection.reset([{foo: 'bar'}]);
CollectionView: Re-render Collection
If you need to re-render the entire collection, you can call the view.render
method. This method takes care of destroying all of the child views that may have previously been opened.
CollectionView's attachHtml
By default the collection view will append the HTML of each ChildView into the element buffer, and then call jQuery's .append
once at the end to move the HTML into the collection view's el
.
You can override this by specifying an attachHtml
method in your view definition. This method takes three parameters and has no return value.
Marionette.CollectionView.extend({
// The default implementation:
attachHtml: function(collectionView, childView, index){
if (collectionView.isBuffering) {
// buffering happens on reset events and initial renders
// in order to reduce the number of inserts into the
// document, which are expensive.
collectionView._bufferedChildren.splice(index, 0, childView);
}
else {
// If we've already rendered the main collection, append
// the new child into the correct order if we need to. Otherwise
// append to the end.
if (!collectionView._insertBefore(childView, index)){
collectionView._insertAfter(childView);
}
}
},
// Called after all children have been appended into the elBuffer
attachBuffer: function(collectionView, buffer) {
collectionView.$el.append(buffer);
},
// called on initialize and after attachBuffer is called
initRenderBuffer: function() {
this.elBuffer = document.createDocumentFragment();
}
});
The first parameter is the instance of the collection view that will receive the HTML from the second parameter, the current child view instance.
The third parameter, index
, is the index of the model that this childView
instance represents, in the collection that the model came from. This is useful for sorting a collection and displaying the sorted list in the correct order on the screen.
Overrides of attachHtml
that don't take into account the element buffer will work fine, but won't take advantage of the 60x performance increase the buffer provides.
CollectionView's resortView
By default the CollectionView
will maintain the order of its collection
in the DOM. However on occasions the view may need to re-render to make this possible, for example if you were to change the comparator on the collection. By default CollectionView
will call render
when this happens, but there are cases where this may not be suitable. For instance when sorting the children
in a CompositeView
, you want to only render the internal collection.
var cv = new Marionette.CollectionView({
collection: someCollection,
resortView: function() {
// provide custom logic for rendering after sorting the collection
}
});
CollectionView's viewComparator
CollectionView allows for a custom viewComparator
option if you want your CollectionView's children to be rendered with a different sort order than the underlying Backbone collection uses.
var cv = new Marionette.CollectionView({
collection: someCollection,
viewComparator: 'otherFieldToSortOn'
});
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.
CollectionView's filter
CollectionView allows for a custom filter
option if you want to prevent some of the underlying collection
's models from being rendered as child views. The filter function takes a model from the collection and returns a truthy value if the child should be rendered, and a falsey value if it should not.
var cv = new Marionette.CollectionView({
childView: SomeChildView,
emptyView: SomeEmptyView,
collection: new Backbone.Collection([
{ value: 1 },
{ value: 2 },
{ value: 3 },
{ value: 4 }
]),
// Only show views with even values
filter: function (child, index, collection) {
return child.get('value') % 2 === 0;
}
});
// renders the views with values '2' and '4'
cv.render();
// change the filter
cv.filter = function (child, index, collection) {
return child.get('value') % 2 !== 0;
};
// renders the views with values '1' and '3'
cv.render();
// remove the filter
// note that using `delete cv.filter` will cause the prototype's filter to be used
// which may be undesirable
cv.filter = null;
// renders all views
cv.render();
CollectionView's children
The CollectionView uses Backbone.BabySitter to 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.
var cv = new Marionette.CollectionView({
collection: someCollection
});
cv.render();
// retrieve a view by model
var v = cv.children.findByModel(someModel);
// iterate over all of the views and process them
cv.children.each(function(view){
// process the `view` here
});
For more information on the available features and functionality of the .children
, see the Backbone.BabySitter documentation.
CollectionView destroy
CollectionView implements a destroy
method, which is called by the region managers automatically. As part of the implementation, the following are performed:
- unbind all
listenTo
events - unbind all custom view events
- unbind all DOM events
- unbind all child views that were rendered
- remove
this.el
from the DOM - call an
onDestroy
event on the view, if one is provided - the
CollectionView
is returned
By providing an onDestroy
event in your view definition, you can run custom code for your view that is fired after your view has been destroyed and cleaned up. This lets you handle any additional clean up code without having to override the destroy
method.
Marionette.CollectionView.extend({
onDestroy: function() {
// custom cleanup or destroying code, here
}
});
© 2016 Muted Solutions, LLC
Licensed under the MIT License.
https://marionettejs.com/docs/v2.4.7/marionette.collectionview.html