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Passed parameter to initialize() view is undefined in Backbone.js

I'm working on a Backbone.js app which utilizes a 'master view' which all views and subviews extend from.
Master view
define(['backbone'], function (Backbone) {
return Backbone.View.extend({
events: {
},
showSuccess: function (msg) {
alert(msg);
}
});
});
I then have a Main View which generates the page, this can call on sub views for smaller parts:
define(['backbone','masterView', 'mySubView'], function (Backbone, mView, mySubView) {
var mainView = mView.extend({
events: function () {
return _.extend({}, coreView.prototype.events, {
});
},
render: function () {
var sub = new mySubView({'foo': 'bar'});
}
});
return new mainView();
});
Finally, my subview, which when it's initialised, it says that options is undefined.
define(['backbone','masterView', 'mySubView'], function (Backbone, mView, mySubView) {
var subView = mView.extend({
events: function () {
return _.extend({}, coreView.prototype.events, {
});
},
initialize: function (options) {
console.log(options);
}
});
return new subView();
});
In this setup, why is options undefined when I passed them in my MainView? If the subview doesn't extend masterView, but Backbone.view instead, it works fine.

Your last line in the subview file:
return new subView();
You're returning a new instance instead of returning the constructor in the subview module. It should be:
return subView;
Note that as a convention, JavaScript code should use PascalCase for types (constructor, classes, etc.), and instances (variables, properties, etc.) should use camelCase.
Also, I'm sharing tricks on how to design a good base class with Backbone. You could shift the responsibility of merging the events to the base class instead of each child class.

How to render a collection with a Marionette's ItemView?

I'm trying to render the response from an API (JSON) with Backbone.Marionette.ItemView. Not sure why it is not working.
I'm using marionette v2.4.7 (on purpose);
Here is the handlebars template:
<script id="feed-post" type="text/x-handlebars-template">
{{#each posts}}
<img src="{{author.image_url}}" alt="">
<p>{{author.name}}</p>
<span>TODO TIMESTAMP</span>
<p>{{body}}</br>{{topic_type}}</p>
{{/each}}
</script>
Here is my full app.js (all Backbone logic in this file);
// Model
var Post = Backbone.Model.extend({
defaults: {
authorPic: 'Unknown',
authorName: 'Unknown',
timestamp: 'Unknown',
body: 'Not available',
comments: '0'
}
});
// Collection
var Posts = Backbone.Collection.extend({
model: Post,
url: 'http://localhost:4321/blogposts',
initialize: function(){
this.fetch();
}
});
// View
var PostView = Marionette.ItemView.extend({
el: '#content',
template: Handlebars.compile($("#feed-post").html()),
});
//Config
var chunkPosts = new Posts();
var myview = new PostView({collection: chunkPosts});
Also, I tried to console.log the view and it looks like the models are in there.

This answer is tailored to Marionette v2.4.7. LayoutView and ItemView were merged and renamed to View back in v3.0.0.
From the doc on ItemView:
Rendering this view will convert the someCollection collection in to
the items array for your template to use.
You are using posts in your template while the doc says it will be called items.
As a reference, here's the exact code doing that in the ItemView source:
// Serialize the model or collection for the view. If a model is
// found, the view's `serializeModel` is called. If a collection is found,
// each model in the collection is serialized by calling
// the view's `serializeCollection` and put into an `items` array in
// the resulting data. If both are found, defaults to the model.
// You can override the `serializeData` method in your own view definition,
// to provide custom serialization for your view's data.
serializeData: function() {
if (!this.model && !this.collection) {
return {};
}
var args = [this.model || this.collection];
if (arguments.length) {
args.push.apply(args, arguments);
}
if (this.model) {
return this.serializeModel.apply(this, args);
} else {
return {
items: this.serializeCollection.apply(this, args)
};
}
},
The last lines show that for a collection, a new object with items as the only attribute is returned.
It's mentioned that you can override the serializeData function, more information and examples are available in the doc.
You still need to call render on the view and since the collection's fetch is async, you won't have items out of the box so you should wire a listener.
First, don't fetch in the initialize of a collection, it makes the collection pretty much useless for any other use-case.
var Posts = Backbone.Collection.extend({
model: Post,
url: 'http://localhost:4321/blogposts',
});
Listen for the collection sync event, then fetch within the view instead.
var PostView = Marionette.ItemView.extend({
el: '#content',
template: Handlebars.compile($('#feed-post').html()),
initialize: function () {
this.listenTo(this.collection, 'sync', this.render);
this.collection.fetch();
},
});
Marionette even offers collectionEvents:
var PostView = Marionette.ItemView.extend({
// ...snip...
collectionEvents: {
"sync": "render"
}
// ...snip...
});

Passing a model to a LayoutView Backbone.Marionette

I am attempting to pass a model to a LayoutView so that the particular model attributes can be edited in the view.
In my ItemView I have an event that grabs the selected model and assigns it to my global App-
var ItemView = Backbone.Marionette.ItemView.extend({
template: _.template(ItemTemplate),
tagName: "tr",
attributes: function(){
return {
"id": this.model.get('id'),
"class": "tr"
};
},
events: {
"click #edit" : "edit"
},
edit: function() {
App.EditModel = this.model;
console.log(App.EditModel); // <-- prints out the model successfully
App.trigger('edit');
}
})
Then, I am using the App.EditModel in my edit view to pass to my template-
var Layout = Backbone.Marionette.LayoutView.extend({
model: App.EditModel,
template : _.template(EditTemplate),
regions : {
"HomeRegion": "#home"
}
});
return Layout;
});
And in the browser I am getting- "Uncaught ReferenceError: firstName is not defined" because the model is not being mapped correctly.
How should I handle this?

When your layout code is first seen the extend function runs taking in all your options, at this point in time I imagine App.EditModel does not yet exist and so the model is stored as undefined
If you want to pass the model to your LayoutView then you should do this when you instantiate it i.e. new Layout({model: this.model});

how to extend a backbone view

I am new in SPA's with backbone and I am trying to develop a small app by using backbone and requireJs.
The problem I faced is that I can't extend a view by passing a collection.
Well, this is the view with name MenuView.js
define([
'Backbone'
], function (Backbone) {
var MenuView = Backbone.View.extend({
tagName: 'ul',
render: function () {
_(this.collection).each(function (item) {
this.$el.append(new MenuListView({ model: item }).render().el);
}, this);
return this;
}
});
return new MenuView;
});
and this is the router.js in which the error is appeared
define([
'Underscore',
'Backbone',
'views/menu/menuView',
'views/createNew/createNew',
'collections/menu/menuCollection',
], function (_, Backbone, MenuView, CreateNewView,Menucollection) {
var AppRouter = Backbone.Router.extend({
routes: {
'index': 'index',
'action/:Create': 'Create'
},
index: function () {
CreateNewView.clear();
//----------- HERE IS THE PROBLEM ------------
$('#menu').html(MenuView({ collection: Menucollection.models }).render().el);
},
Create: function () {
CreateNewView.render();
}
});
var initialize = function () {
var appRouter = new AppRouter();
Backbone.history.start();
appRouter.navigate('index', { trigger: true });
};
return {
initialize: initialize
};
});
The error message is "object is not a function". I agreed with this since the MenuView is not a function. I tried to extend the MenuView (MenuView.extend({collection:Menucollection.models})) and the error message was "objet[object,object] has no method extend".
I suppose that the way I am trying to do this, is far away from the correct one.
Could anyone suggest how to do this?
Thanks

#Matti John's solution will work, but it's more of a workaround than a best practice IMHO.
As it is, you initializing your view just by requiring it, which:
Limits you to never accept arguments
Hits performance
Makes it really hard to unit-test if you relay on assigning properties ater constructing an instance.
A module should be returning a 'class' view and not an instance on that view.
In MenuView.js I would replace return new MenuView with return MenuView; and intitalzie it when required in router.js.

Your MenuView.js returns an initialized MenuView, so you could just do:
MenuView.collection = Menucollection
Note I haven't selected the models - I think it's better if you don't use the models as a replacement for your view's collection, since it would be confusing to read the code and not have a Backbone collection as the view's collection. You would also lose the method's contained within the collection (e.g. fetch/update).
If you do this, then you would need to update your loop (each is available as a method for the collection):
this.collection.each(function (item) {
this.$el.append(new MenuListView({ model: item }).render().el);
}, this);

The best way to fetch and render a collection for a given object_id

I am trying to implement a simple app which is able to get a collection for a given object_id.
The GET response from the server looks like this:
[
{object_id: 1, text: "msg1"},
{object_id: 1, text: "msg2"},
{object_id: 1, text: "msg3"},
.......
]
My goal is:
render a collection when the user choose an object_id.
The starting point of my code is the following:
this.options = {object_id: 1};
myView = new NeView(_.extend( {el:this.$("#myView")} , this.options));
My question is:
* What is the best way:
1) to set the object_id value in the MyModel in order to
2) trigger the fetch in MyCollection and then
3) trigger the render function in myView?* or to active my goal?
P.S:
My basic code looks like this:
// My View
define([
"js/collections/myCollection",
"js/models/myFeed"
], function (myCollection, MyModel) {
var MyView = Backbone.View.extend({
initialize: function () {
var myModel = new MyModel();
_.bindAll(this, "render");
myModel.set({
object_id: this.options.object_id
}); // here I get an error: Uncaught TypeError: Object function (){a.apply(this,arguments)} has no method 'set'
}
});
return MyView;
});
// MyCollection
define([
"js/models/myModel"
], function (MyModel) {
var MyCollection = Backbone.Collection.extend({
url: function () {
return "http://localhost/movies/" + myModel.get("object_id");
}
});
return new MyCollection
});
//MyModel
define([
], function () {
var MyModel = Backbone.Model.extend({
});
return MyModel
});

There's a few, if not fundamentally things wrong with your basic understanding of Backbone's internals.
First off, define your default model idAttribute, this is what identifies your key you lookup a model with in a collection
//MyModel
define([
], function () {
var MyModel = Backbone.MyModel.extend({
idAttribute: 'object_id'
});
return MyModel
});
in your collection, there is no need to define your URL in the way you defined it, there are two things you need to change, first is to define the default model for your collection and second is to just stick with the base url for your collection
// MyCollection
define([
"js/models/myModel"
], function (MyModel) {
var MyCollection = Backbone.MyCollection.extend({
model: MyModel, // add this
url: function () {
return "http://localhost/movies
}
});
return MyCollection // don't create a new collection, just return the object
});
and then your view could be something along these lines, but is certainly not limited to this way of implementing
// My View
define([
"js/collections/myCollection",
"js/models/myFeed"
], function (MyCollection, MyModel) {
var MyView = Backbone.View.extend({
tagName: 'ul',
initialize: function () {
this.collection = new MyCollection();
this.collection.on('add', this.onAddOne, this);
this.collection.on('reset', this.onAddAll, this);
},
onAddAll: function (collection, options)
{
collection.each(function (model, index) {
that.onAddOne(model, collection);
});
},
onAddOne: function (model, collection, options)
{
// render out an individual model here, either using another Backbone view or plain text
this.$el.append('<li>' + model.get('text') + '</li>');
}
});
return MyView;
});
Take it easy and go step by step
I would strongly recommend taking a closer look at the exhaustive list of tutorials on the Backbone.js github wiki: https://github.com/documentcloud/backbone/wiki/Tutorials%2C-blog-posts-and-example-sites ... try to understand the basics of Backbone before adding the additional complexity of require.js