Again some simple problem with backbone. Instead of long description here is some sample code:
var Group = Backbone.Model.extend({
defaults: {
Product: new Products()
},
initialize: function(data){
var _this = this;
var products = new Products(data.Product);
this.set('Product', products);
this.get('Product').each(function(product){
product.on('destroy', function(){
_this.trigger('change');
}, _this);
});
this.bind('change', this.update, this);
},
update: function(){
console.info("something changed");
console.log(this.get('Product').toJSON());
},
});
So group model contains Product-collection, which obviously contains products. In initialize i am trying to make sure that the update method of the group is called example when product is changed and destroyed. All seems to be working nicely, events get called, attributes look great but it fails when I call destroy method in product model. In update I try to print the contents of product collection and what I get is products BEFORE remove is done. If I call this debug line after 500ms timeout, the contents are ok. Product is removed etc.
So according to my understanding the destroy event of product is called and then passed to group before actual removal from collection is done. What am I doing wrong?
Backbone handles the removal of a destroyed model in a collection by listening to the destroy event on the models: see the source code for Backbone.Model - destroy and Backbone.Collection - _onModelEvent.
The order in which the handlers will be executed is not guaranteed, you will have to use something else. For example, listen to the destroyevent on the collection which will fire after the model is actually removed:
initialize: function(data){
var _this = this;
var products = new Products(data.Product);
this.set('Product', products);
this.get('Product').on("destroy", this.update, this);
this.bind('change', this.update, this);
},
Check this Fiddle http://jsfiddle.net/NUtmt/ for a complete example.
Related
I want to perform an action, clearing parent element, after a collection has fetched his models but prior to the models rendering.
I've stumbled upon before and after render methods yet they are model specific, which will cause my parent element to clear before every model rendering.
I'm able of course to perform the action pre-fetching yet I want it to occur when fetch is done and before models are rendered.
I tried using reset and change events listening on the collection yet both resulted unwanted end result.
Reset event seamed to go in that direction yet the passed argument was the entire collection and not a single model from the collection, therefore using the add event callback wasn't possible due to difference in argument type (collection and not a model as required)
Any ideas how to invoke a callback when fetch a collection fetch is successful yet models are yet to be rendered?
The model contains the returned attributes while collection contains url for fetching and parse method to return argument wrapped object.
Below is the code I use to render the collection view, which is basically rendering each model's view within the collection.
Collection View
---------------
var FoosView = Backbone.View.extend({
el: '#plans',
events: {
//'click tr': 'rowClick'
},
initialize: function() {
this.listenTo(this.collection, 'add', this.renderNew);
_.bindAll(this, "render");
this.render();
},
renderNew: function(FooModel) {
var item = new FooView({model: FooModel});
this.$el.prepend(item.render().$el);
}
...
});
The model view
--------
var FooView = Backbone.View.extend({
tagName: 'li',
initialize: function(options) {
this.options = options || {};
this.tpl = _.template(fooTpl);
},
render: function() {
var data = this.model.toJSON();
this.$el.html(this.tpl(data));
return this;
}
});
Thanks in advance.
OK, I think I understand your question and here is a proposed solution. You are now listening to the reset event on your collection and calling this.renderAll. this.renderAll will take the list of models from the collection and render them to the page, but only AFTER the list element has been emptied. Hope this helps :).
var FoosView = Backbone.View.extend({
el: '#plans',
collection: yourCollection, // A reference to the collection.
initialize: function() {
this.listenTo(this.collection, 'add', this.renderNew);
this.listenTo(this.collection, 'reset', this.renderAll);
},
renderAll: function() {
// Empty your list.
this.$el.empty();
var _views = []; // Create a list for you subviews
// Create your subviews with the models in this.collection.
this.collection.each(function(model) {
_views.push(new FooView({model: model});
});
// Now create a document fragment so as to not reflow the page for every subview.
var container = document.createDocumentFragment();
// Append your subviews to the container.
_.each(_views, function(subview) {
container.appendChild(subview.render().el);
});
// Append the container to your list.
this.$el.append(container);
},
// renderNew will only run on the collections 'add' event.
renderNew: function(FooModel) {
var item = new FooView({model: FooModel});
this.$el.prepend(item.render().$el);
}
});
I am forced to assume a few things about you html, but I think the above code should be enough to get you up and running. Let me know if it works.
I'm not totally sure about what you are asking but have you tried:
MyCollection.fetch({
success: function(models,response) {
//do stuff here
}
});
Also you may be interested taking a look at http://backbonejs.org/#Model-parse
Hope it helps!
Edit: there is no direct link between fetching and rendering my bet is that you binded rendering to model change.
USE===============>>>> http://backbonejs.org/#Model-parse
Backbone.js newbie here.
General question: What is the best practice to track the number of models in a collection in order to display it on the UI? My use cases can involve changes on the server side so each time the collection is sync'd I need to be able to update the UI to the correct number from storage.
I'm using Backbone.js v1.0.0 and Underscore v1.4.4 from the amdjs project and Require.js v2.1.6.
Specific example: Simple shopping cart showing "number of items in the cart" that continually updates while the user is adding/removing items. In this example I'm almost there but (1) my code is always one below the real number of models and (2) I feel that there is a much better way to do this!
Here's my newbie code.
First, I have a collection of items that the user can add to their cart with a button. (NOTE: all AMD defines and returns are removed in code examples for brevity.)
var PackagesView = Backbone.View.extend({
el: $("#page"),
events: {
"click .addToCart": "addToCart"
},
initialize: function(id) {
this.collection = new PackagesCollection([],{id: id.id});
this.collection.fetch({
reset: true
});
this.collection.on("reset", this.render, this);
},
render: function(){
//other rendering stuff here
..............
//loop through models in collection and render each one
_.each(this.collection.models, function(item){
that.renderPackages(item);
});
}
renderPackages: function(item){
var packageView = new PackageView({
model: item
});
this.$el.append(packageView.render().el);
},
Next I have the view for each individual item in the cart PackageView which is called by the PackagesView code above. I have a "add to cart" button for each Package that has a "click" event tied to it.
var PackageView = Backbone.View.extend({
tagName:"div",
template:$(packageTemplate).html(),
events: {
"click .addToCart": "addToCart"
},
render:function () {
var tmpl = _.template(this.template);
this.$el.html(tmpl(this.model.toJSON()));
return this;
},
addToCart:function(){
cartView = new CartView();
cartView.collection.create(new CartItemModel(this.model));
}
Finally, I have a CartView that has a collection of all the items in the cart. I tried adding a listenTo method to react to changes to the collection, but it didn't stay in sync with the server either.
var CartView = Backbone.View.extend({
el: $("#page"),
initialize:function(){
this.collection = new CartCollection();
this.collection.fetch({
reset: true
});
this.listenTo(this.collection, 'add', this.updateCartBanner);
this.collection.on("reset", this.render, this);
},
render: function(){
$('#cartCount').html(this.collection.length);
},
updateCartBanner: function(){
//things did not work here. Just putting this here to show something I tried.
}
End result of specific example: The .create works correctly, PUT request sent, server adds the data to the database, "reset" event is called. However, the render() function in CartView does not show the right # of models in the collection. The first time I click a "add to cart" button the $('#cartCount') element does not get populated. Then anytime after that it does get populated but I'm minus 1 from the actual count on the server. I believe this is because I have a .create and a .fetch and the .fetch is happening before the .create finishes so I'm always 1 behind the server.
End result, I'm not structuring this the right way. Any hints in the right direction would be helpful!
You can try like this:
collection.on("add remove reset sync", renderCallback)
where renderCallback is function which refresh your UI.
Found an answer to my question, but could definitely be a better method.
If I change my code so instead of a separate view for each model in the collection as I have above, I have one view that iterates over all the models and draws then it will work. I still need to call a .create followed by a .fetch with some unexpected behavior, but the end result is correct.
Note that in this code I've completely done away with the previous PackageView and everything is drawn by PackagesView now.
var PackagesView = Backbone.View.extend({
el: $("#page"),
events: {
"click .addToCart": "addToCart"
},
initialize: function(id) {
this.collection = new PackagesCollection([],{id: id.id});
this.collection.fetch({
reset: true
});
this.collection.on("reset", this.render, this);
},
render: function(){
var that = this;
var tmpl = _.template($(packageTemplate).html());
//loop through models in collection and render each one
_.each(this.collection.models, function(item){
$(that.el).append(tmpl(item.toJSON()));
});
},
addToCart:function(e){
var id= $(e.currentTarget).data("id");
var item = this.collection.get(id);
var cartCollection = new CartCollection();
var cartItem = new CartItemModel();
cartCollection.create(new CartItemModel(item), {
wait: true,
success: function() {
console.log("in success create");
console.log(cartCollection.length);
},
error:function() {
console.log("in error create");
console.log(cartCollection.length);
}
});
cartCollection.fetch({
wait: true,
success: function() {
console.log("in success fetch");
console.log(cartCollection.length);
$('#cartCount').html(cartCollection.length);
},
error:function() {
console.log("in error fetch");
console.log(cartCollection.length);
}
});
Result: The $('#cartCount') in the .fetch callback injects the correction number of models. Unexpectedly, along with the correct .html() value the Chrome console.log return is (server side had zero models in the database to start with):
in error create PackagesView.js:88
0 PackagesView.js:89
in success fetch PackagesView.js:97
1
And I'm getting a 200 response from the create, so it should be "success" for both callbacks. I would have thought that the Backbone callback syntax for create and fetch were the same. Oh well, it seems to work.
Any feedback on this method is appreciated! Probably a better way to do this.
Incidentally this goes against the general advice here, although I do have a "very simple list" so perhaps its OK in the long run.
In a backbone model, is it possible to trigger an event in the initialize function, for a nested view? I based my current code off this example: https://stackoverflow.com/a/8523075/2345124 and have updated it for backbone 1.0.0. Here is my initialize function, for a Model:
var Edit = Backbone.Model.extend({
initialize: function() {
this.trigger('marquee:add');
this.on('change', function(){
this.trigger('marquee:add');
});
}
...
}
I'm trying to call a method renderMarquee when the model is initialized:
var EditRow = Backbone.View.extend({
initialize: function() {
this.listenTo(this.model, "change", this.render); // works
this.listenTo(this.model, "marquee:add", this.renderMarquee); // only called when changed, but not when initially created
...
}
renderMarquee IS called when the model is changed, but not when it is initialized. 'change' events work as expected (this.render is called). Any thoughts?
Thanks!
I am currently facing a similar problem. I needed to trigger the change event in the initialize method of my model.
I looked into the backbone code which revealed why this is not happening:
var Model = Backbone.Model = function(attributes, options) {
...
this.set(attrs, options);
this.changed = {};
this.initialize.apply(this, arguments);
};
the set is executed before the initialize and this.change is emptied setting the model state to "nothing has changed".
In order to overwrite behavior this I added the following code to my initialize method.
initialize: function(attributes, options) {
...
this.changed = attributes;
this.trigger('change');
for (attr_name in attributes) {
this.trigger('change:' + attr_name);
}
},
I trigger all change events manually, this is important for me since inheriting models may bind to change or change:attrxy. But this is not enough, because if I just trigger the events the changedAttributes() method would return false therefore I also set this.changed to the current attributes.
This doesn't make a lot of sense because you are initializing the model somewhere prior to doing the view.listenTo call. Unfortunately, you don't really have a choice in that matter.
You are probably going to want to move the event handling to a Backbone.Collection which already has built in events you can listen on for adding/removing.
I am trying to create my first backbone app and am having some difficulty getting my head around how I am meant to be using views.
What I am trying to do is have a search input that each time its submitted it fetches a collection from the server. I want to have one view control the search input area and listen to events that happen there (a button click in my example) and another view with sub views for displaying the search results. with each new search just prepending the results into the search area.
the individual results will have other methods on them (such as looking up date or time that they where entered etc).
I have a model and collection defined like this:
SearchResult = Backbone.model.extend({
defaults: {
title: null,
text: null
}
});
SearchResults = Backbone.Collection.extend({
model: SearchResult,
initialize: function(query){
this.query = query;
this.fetch();
},
url: function() {
return '/search/' + this.query()
}
});
In my views I have one view that represents the search input are:
var SearchView = Backbone.View.extend({
el: $('#search'),
events: {
'click button': 'doSearch'
},
doSearch: function() {
console.log('starting new search');
var resultSet = new SearchResults($('input[type=text]', this.el).val());
var resultSetView = new ResultView(resultSet);
}
});
var searchView = new SearchView();
var ResultSetView = Backbone.View.extend({
el: $('#search'),
initialize: function(resultSet) {
this.collection = resultSet;
this.render();
},
render: function() {
_(this.collection.models).each(function(result) {
var resultView = new ResultView({model:result});
}, this);
}
});
var ResultView = Backbone.view.extend({
tagName: 'div',
model: SearchResult,
initialize: function() {
this.render();
},
render: function(){
$(this.el).append(this.model.get(title) + '<br>' + this.model.get('text'));
}
});
and my html looks roughly like this:
<body>
<div id="search">
<input type="text">
<button>submit</button>
</div>
<div id="results">
</div>
</body>
In my code it gets as far as console.log('starting new search'); but no ajax calls are made to the server from the initialize method of the ResultSetView collection.
Am I designing this right or is there a better way to do this. I think because the two views bind to different dom elements I should not be instantiating one view from within another. Any advice is appreciated and if I need to state this clearer please let me know and I will do my best to rephrase the question.
Some problems (possibly not the only ones):
Your SearchView isn't bound to the collection reset event; as written it's going to attempt to render immediately, while the collection is still empty.
SearchView instantiates the single view ResultView when presumably it should instantiate the composite view ResultSetView.
You're passing a parameter to the SearchResults collection's constructor, but that's not the correct way to use it. See the documentation on this point.
You haven't told your ResultSetView to listen to any events on the collection. "fetch" is asynchronous. When completed successfully, it will send a "reset" event. Your view needs to listen for that event and then do whatever it needs to do (like render) on that event.
After fixing all the typos in your example code I have a working jsFiddle.
You see like after clicking in the button an AJAX call is done. Of course the response is an error but this is not the point.
So my conclusion is that your problem is in another part of your code.
Among some syntax issues, the most probable problem to me that I see in your code is a race condition. In your views, you're making an assumption that the fetch has already retrieved the data and you're executing your views render methods. For really fast operations, that might be valid, but it gives you no way of truly knowing that the data exists. The way to deal with this is as others have suggested: You need to listen for the collection's reset event; however, you also have to control "when" the fetch occurs, and so it's best to do the fetch only when you need it - calling fetch within the search view. I did a bit of restructuring of your collection and search view:
var SearchResults = Backbone.Collection.extend({
model: SearchResult,
execSearch : function(query) {
this.url = '/search/' + query;
this.fetch();
}
});
var SearchView = Backbone.View.extend({
el: $('#search'),
initialize : function() {
this.collection = new SearchResults();
//listen for the reset
this.collection.on('reset',this.displayResults,this);
},
events: {
'click button': 'doSearch'
},
/**
* Do search executes the search
*/
doSearch: function() {
console.log('starting new search');
//Set the search params and do the fetch.
//Since we're listening to the 'reset' event,
//displayResults will execute.
this.collection.execSearch($('input[type=text]', this.el).val());
},
/**
* displayResults sets up the views. Since we know that the
* data has been fetched, just pass the collection, and parse it
*/
displayResults : function() {
new ResultSetView({
collection : this.collection
});
}
});
Notice that I only created the collection once. That's all you need since you're using the same collection class to execute your searches. Subsequent searches only need to change the url. This is better memory management and a bit cleaner than instantiating a new collection for each search.
I didn't work further on your display views. However, you might consider sticking to the convention of passing hashes to Backbone objects. For instance, in your original code, you passed 'resultSet' as a formal parameter. However, the convention is to pass the collection to a view in the form: new View({collection: resultSet}); I realize that that's a bit nitpicky, but following the conventions improves the readability of your code. Also, you ensure that you're passing things in the way that the Backbone objects expect.
I'm learning Backbone.js for the first time and I'm having an issue trying to get a custom event from triggering (or from the View from recognising when it's been triggered)?
You can see my Collection code here: https://github.com/Integralist/Backbone-Playground/blob/master/Assets/Scripts/App/main.js#L72-86 which when initialized it triggers a custom collection:init event.
var Contacts = Backbone.Collection.extend({
model: Contact,
initialize: function(){
this.trigger('collection:init');
this.bind('add', this.model_added, this);
},
model_added: function(){
console.log('A new model has been created so trigger an event for the View to update the <select> menu');
}
});
But later on in my View where I'm listening for that event I can't get the function populate to fire: https://github.com/Integralist/Backbone-Playground/blob/master/Assets/Scripts/App/main.js#L90-107
var ContactsView = Backbone.View.extend({
initialize: function(){
console.log(contacts.models, 'get initial model data and populate the select menu?');
},
events: {
'collection:init': 'populate',
'change select': 'displaySelected'
},
populate: function(){
console.log('populate the <select> with initial Model data');
},
displaySelected: function (event) {
console.log('get model data and display selected user', event);
}
});
Any ideas what I'm doing wrong?
The events hash in a view is used to bind events from the DOM to your view, e.g. events raised by the elements in your rendered view. To listen to events raised by your collection, you will have to set them manually:
var ContactsView = Backbone.View.extend({
initialize: function(){
contacts.on("collection:init",this.populate,this);
}
...
});
Note that you are using a global contacts variable, I would advise to use Backbone mechanisms and pass your collection to the constructor, as you do with the el:
var ContactsView = Backbone.View.extend({
initialize: function(){
console.log(this.collection.models);
this.collection.on("collection:init",this.populate,this);
}
...
});
var contacts_view = new ContactsView({
el: $('#view-contacts'),
collection:contacts
});
As #mu said in the comments, as is, your event won't do anything since you trigger it in the initialize method of the collection, which is automatically called by the constructor of the collection therefore before you can bind anything in the view. See this Fiddle to visualize the call order : http://jsfiddle.net/yRuCN/
Trigger it elsewhere, or, if I read correctly your intent, you (probably) want to use the built in reset event:
var ContactsView = Backbone.View.extend({
initialize: function(){
this.collection.on("reset",this.populate,this);
}
...
});
See http://jsfiddle.net/yRuCN/1/ for an example with potential uses.