backbone js view event binding only to views elements - backbone.js

Hi I'm learning backbone and I am having trouble with binding events to views. My problem is that I have a view constructor that when called, binds all views to a button press event that is only part of one view. I would like the button press event to be bound to only the 1 view that contains the button.
http://jsbin.com/tunazatu/6/edit?js,console,output
click on all of the view buttons
then click back to view 1
click the red button (all view's models console.log their names)
So I've looked at the code from this post mutliple event firing which shows that you can have multiple views that have the same el thru tagName but map events only to their html elements. This is also what is done in the localtodos example from Jérôme Gravel-Niquet
I have also tried not declaring el /tunazatu/7/edit?js,console,output but then it seems like no event gets bound.
var AppView = Backbone.View.extend({
tagName:"div", //tagName defined
getName:function(){
console.log(this.model.get('name'));
},
initialize:function(options){
this.listenTo(this.model, 'change', this.render);
var temp_mapper = {appView1:'#route1',appView2:'#route2',appView3:'#route3'};
var m_name = this.model.get('name');
this.template = _.template($(temp_mapper[m_name]).html()); //choose the correct template
},
render:function(){
var temp = this.template(this.model.toJSON()); //populate the template with model data
var newElement = this.$el.html(temp); //put it in the view's tagName
$('#content').html(newElement);
},
events:{
"click button":"log"
},
log:function(){
this.getName();
}
});

Your problem is that your AppView really looks like this:
var AppView = Backbone.View.extend({
el: "#content",
//...
Every time you create a new AppView, you bind another event delegator to #content but you never remove those delegations. If you create three AppViews, you end up with three views listening to click button inside #content.
I would recommend two things:
Avoid trying to re-use views, create and destroy them (via View#remove) as needed. Views should be lightweight enough that putting them together and tearing them down should be cheap.
Don't bind multiple views to the same el. Instead, let each view create its own el and then let the caller put that el inside some container.
If you do both of those things then your problem will go away. Your AppView would look more like this:
var AppView = Backbone.View.extend({
render: function() {
this.$el.html(this.template(this.model.toJSON()));
return this; // Common practise, you'll see why shortly.
},
// As you already have things...
});
Then your router methods would look more like this:
view1: function() {
if(this.appView)
this.appView.remove();
this.appView = this.createView('appView1');
$('#content').html(this.appView.render().el);
// that `return this` is handy ----------^^
},
If you must stick with your current approach then you'll have to call undelegateEvents on the current AppView before you render another one and delegateEvents on the new AppView after you render it.
But really, don't be afraid to destroy views that you don't need right at this moment: destroy any view that you don't need on the page right now and create new instances when you need them. There are cases where you don't want to destroy your views but you can usually avoid it.

Related

Rendering a closed Marionette view

Shouldn't a closed Marionette view re-delegate the defined events (events, modelEvents, CollectionEvents) when rendering again?
It seems as if I have to manually call delegateEvents after closing and re-rendering a view. Otherwise the view won't work as expected.
http://jsfiddle.net/4DCeY/
var app = new Marionette.Application();
app.addRegions({
main: '.main'
});
var MyView = Marionette.ItemView.extend({
template: _.template('Hi, I\'m a view! Foo is: <%= foo %>'),
modelEvents: {
'change': 'onChange'
},
onChange: function() {
alert('change!');
}
});
var Model = Backbone.Model.extend({});
app.addInitializer(function() {
var m = new Model({foo: 'bar'});
var myView = new MyView({
model: m
});
app.main.show(myView);
myView.close();
app.main.show(myView);
m.set({foo: 'baz'});
});
$(document).ready(function(){
app.start();
});
If I understand your question right, there are multiple open github issues about this.
For example:
https://github.com/marionettejs/backbone.marionette/pull/654
https://github.com/marionettejs/backbone.marionette/issues/622
Last time I checked, Derick (the creator of Marionette) didn't feel like reusing closed views should be something regions should do.
So you could
simply create a new view and show that one
manually call delegateEvents - but there was an issue with multiple event bindings that I can't remember right now, so be careful about that one (not at work right now, so can't take a peek at the code, sorry)
write your own region manager
or wait and see if Derick will merge one of the pull requests
a couple of points:
You do not need to call myView.close() Marionette Region will take care of that when you show another view
Marionette.Region will not replace the same view with itself. It will just skip the redundant procedure if you want to test this correctly you need 2 views
If you want a change in model to invoke render you must explicitly write it
I altered the jsfiddle with the following things:
added myView1 and myView2
removed explicit call to myView.close
added a call for this.render() from the onChange function
Here is the corrected jsfiddle http://jsfiddle.net/4DCeY/1/ :
app.addInitializer(function() {
var m = new Model({foo: 'bar'});
var myView1 = new MyView({
model: m
});
var myView2 = new MyView({
model: m
});
app.main.show(myView1);
app.main.show(myView2);
m.set({foo: 'baz'});
});
And:
onChange: function() {
alert('change!');
this.render();
}

rerender Backbone views without losing references to dom

I have the following problem with backbone and I'd like to know what strategy is the more appropriated
I have a select control, implemented as a Backbone view, that initially loads with a single option saying "loading options". So I load an array with only one element and I render the view.
The options will be loaded from a collection, so I fire a fetch collection.
Then I initialize a component that is in charge of displaying in line errors for every field. So I save a reference of the dom element of the combo.
When the fetch operation is finally ready, I rerender the control with all the options loaded from the collection.
To render the view I user something like this:
render: function() {
this.$el.html(this.template(this.model.attributes));
return this;
}
pretty standard backbone stuff
the problem is that after rendering the view for the second time the reference of the dom is no longer valid,
perhaps this case is a bit strange, but I can think of lots of cases in which I have to re-render a view without losing their doms references (a combo that depends on another combo, for example)
So I wonder what is the best approach to re-render a view without losing all the references to the dom elements inside the view...
The purpose of Backbone.View is to encapsulate the access to a certain DOM subtree to a single, well-defined class. It's a poor Backbone practice to pass around references to DOM elements, those should be considered internal implementation details of the view.
Instead you should have your views communicate directly, or indirectly via a mediator.
Direct communication might look something like:
var ViewA = Backbone.View.extend({
getSelectedValue: function() {
return this.$(".combo").val()
}
});
var ViewB = Backbone.View.extend({
initialize: function(options) {
this.viewA = options.viewA;
},
doSomething: function() {
var val = this.viewA.getSelectedValue();
}
});
var a = new ViewA();
var b = new ViewB({viewA:a});
And indirect, using the root Backbone object as a mediator:
var ViewA = Backbone.View.extend({
events: {
"change .combo" : "selectedValueChanged"
},
selectedValueChanged: function() {
//publish
Backbone.trigger('ViewA:changed', this.$('.combo').val());
}
});
var ViewB = Backbone.View.extend({
initialize: function(options) {
//subscribe
this.listenTo(Backbone, 'ViewA:changed', this.doSomething);
},
doSomething: function(val) {
//handle
}
});
var a = new ViewA();
var b = new ViewB();
The above is very generic, of course, but the point I'm trying to illustrate here is that you shouldn't have to worry whether the DOM elements are swapped, because no other view should be aware of the element's existence. If you define interfaces between views (either via method calls or mediated message passing), your application will be more maintainable and less brittle.

Trigger click event from one file from another in BackboneJS

in my project i am not able to trigger click event registered in one backbone view from another backbone view. its actually i am having a file type input placed hidden from the user and i need to trigger the file type input.
var FileView = Backbone.View.extend({
....
events : {
"click .delete-image" : "deleteFile",
}
....
});
var FilesView = Backbone.View.extend({
....
events : {
"click #attach" : "attachFile",
},
attachFile : function() {
this.fileView.trigger("click .delete-image");
}
....
});
but i tried like this the event is not get triggered. how is it possible.
the events hash attaches itself to the jquery element that represents the view, not the backbone view itself. So you would most likely have to do something like this:
attachFile : function() {
$('.delete-image', this.fileView.$el).trigger("click");
}
but I would discourage this kind of non-pattern and instead work towards using something we call an Event Aggregation pattern. You can find a collection of really good SO solutions next:
fire an event from one view to another in backbone
Backbone.js global events
Multiple view on same page with backbone.js

marionette simple event delegation

I am trying to add a simple event to the children under my compositeview but it is not triggering at all..and frankly I am not sure why, it seems so simple, I could do this just fine with normal backbone.view.
In the example below, the alert is not triggered at all, however when I purposefully change the function name the event binds to , to something else that doesnt exist, it complaints that the function doesnt exist, so I think it's something else...help?
App.View.ContentContainer = Backbone.Marionette.CollectionView.extend({
className:'content_container',
itemView:App.View.ContentBrowseItem,
events:{
'click .browse_item':'focus_content'
},
initialize:function () {
//this.views = {} //indexed by id
//this.create_modal_container()
var coll = this.collection
coll.calculate_size()
coll.sort_by('title', -1)
},
focus_content:function (e) {
alert('here???')
var $modal_container = this.$modal_container
var content_id = $(e.currentTarget).data('content-id')
var $selected_view = this.views[content_id]
var $focused_content = new App.View.FocusedItem({model:$selected_view.model})
$modal_container.empty().show().append($focused_content.el).reveal().bind('reveal:close', function () {
$focused_content.close()
})
return false
},
onShow:function(){
this.$el.addClass('content_container').isotope({
selector:'.content_item',
resizable:true,
layoutMode:'masonry',
masonry:{ columnWidth:64 }
})
}
EDIT: this is the resulting HTML: http://pastebin.com/uW2X8iPp the div.content_container is the resulting el of App.View.ContentContainer
Is .browse_item a selector for the App.View.ContentBrowseItem itemView element? In that case, you need to bind the event in the ItemView definition, not in the CollectionView definition. The reason is that events are bound when a view is rendered. The CollectionView itself is rendered before any of its child itemViews.
Also, if you are opening up another modal view on this click event, I would let the app handle that, rather than your CollectionView
Try something like this:
App.View.ContentBrowseItem = Backbone.Marionette.ItemView.extend({
...
initialize: function() {
// Maintain context on event handlers
_.bindAll(this, "selectItem")
},
events: {
"click" : "selectItem"
}
selectItem: function() {
App.vent.trigger("item:select", this.model);
}
...
});
And to actually show the modal detail view:
App.vent.on("item:select", function(itemModel) {
var detailView = new App.View.FocusedItem({ model: itemModel });
// You may also want to create a region for your modal container.
// It might simplify some of your `$modal_container.empty().show().append(..).etc().etc()
App.modalRegion.show(detailView);
});
Allowing each of your views to handle their own events is part of what makes Backbone and Marionette so beautiful. You'll just want to avoid one view getting all up in another view's business (eg. a CollectionView trying to handle its ItemView's events, an ItemView creating event bindings to show and close a separate modal view, etc.)
Hope this helps!

Can't get iscroll4 to play with backbone view

I am trying to use iScroll4 inside a backbone.js application. I have several dynamically loaded lists, and I want to initialize iScroll after the appropriate view has loaded.
I'm trying to call 'new iScroll' when the list view finishes loading, but cannot for the life of me figure out how to do this.
Has anyone gotten these two to work together? Is there an example out there of a backbone view initializing a scroller once its element has loaded?
you are correct, you have to load the view first,
or defenately refresh iscroll afterwards
in our applications, we usually use the render method to render the view
and have a postRender method that handles initialization of these extra plugins like iscroll
of course you need some manual work to get it done but this is the gist of it:
var myView = Backbone.View.extend({
// more functions go here, like initialize and stuff... but I left them out because only render & postRender are important for this topic
// lets say we have a render method like this:
render: function() {
var data = this.collection.toJSON();
this.$el.html(Handlebars.templates['spotlightCarousel.tmpl'](data));
return this;
},
// we added the postRender ourself:
postRender: function() {
var noOfSlides = this.collection.size();
$('#carouselscroller').width(noOfSlides * 320);
this.scroller = new IScroll('carouselwrapper', {
snap: true,
momentum: false,
hScrollbar: false
});
}
});
now the calling of these methods
we did this outside our view as we like some view manager to handle this
but it boils down to this
var col = new myCollection();
var view = new myView({ collection: col });
$('#wrapper').html(view.render().$el); // this chaining is only possible due to the render function returning the whole view again.
// here we always test if the view has a postRender function... if so, we call it
if (view.postRender) {
view.postRender();
}

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