I have this annoying problem and I get the feeling it's because we can't use defaults for Backbone Views as we would with Backbone Models. My goal was to use defaults with a Backbone View and then override them with options passed to the initialize function as desired. The problem that I am having is that when I call this.collection Backbone doesn't match this with this.defaults.collection, as I would expect. I get a null point exception when I call this.collection in the initialize function even though I assigned collection in defaults.
Perhaps what I need is this call in my initialize function:
this.options = _.extend(this.defaults, this.options);
however, in this case, then defaults is not doing anything special. this.defaults could be called this.cholo. I guess I am wondering why defaults/attributes won't act the same as Backbone Models.
I have the following code:
var IndexView = Backbone.View.extend({
el: '#main-div-id',
defaults: function(){
return{
model: null,
collection: collections.users,
childViews:{
childLoginView: null,
childRegisteredUsersView: null
}
}
},
events: {
'click #loginAsGuest': 'onLoginAsGuest',
'click #accountRecoveryId': 'onAccountRecovery'
},
initialize: function (opts) {
this.options = Backbone.setViewOptions(this, opts);
Backbone.assignModelOptions(this,this.options);
_.bindAll(this, 'render', 'onFetchSuccess', 'onFetchFailure');
this.listenTo(this.collection, 'add remove reset', this.render); //this.collection is not defined here
this.collection.fetch({ //null pointer here, this.collection is not defined
success: this.onFetchSuccess.bind(this),
error: this.onFetchFailure.bind(this)
});
},
render: function () {
//removed code because it's extraneous for this example
},
onFetchSuccess: function () {},
onFetchFailure: function () {}
},
{ //classProperties
givenName: '#IndexView'
});
...by the way, in order to make events different for each instance of the view, should I turn events into a function like defaults?
There is really nothing special about the defaults literal within a Backbone.Model. If you take a look at the Backbone source, they're essentially doing this within the model constructor
Backbone.Model = function( attributes, options ) {
// simplified for example
var attrs = _.defaults( {}, attributes, this.defaults );
this.set( attrs, options );
};
You can take the exact same approach when setting up your views
var myView = Backbone.View.extend( {
options: {
// your options
},
initialize: function( options ) {
this.options = _.defaults( {}, options, this.options );
}
} );
If you would like to define your options as a function so it's evaluated at runtime, you can use the following
var myView = Backbone.View.extend( {
options: function() {
// your options
},
initialize: function( options ) {
this.options = _.defaults( {}, options, _.result(this, 'options') );
}
} );
To answer your other question about different events per instance, yes you can either define it as a function and include the logic within that function OR simply pass events: { ... } as an option when instantiating the view.
Hope this helps.
Related
I'm learning Marionette.js and have a scenario, where my app has:
app.addRegions({
main: '#omen',
newItem: '#addnewitem',
counter: '#counter'
});
These regions. I have these Model/Collections:
var Item = Backbone.Model.extend(),
Items = Backbone.Collection.extend({
model: Item,
url: 'api/items'
}),
I have an Item view and Items view:
ItemView = Mn.ItemView.extend({
tagName: 'tr',
template: '#itemView',
events: {
'click #btnDeleteBook' : 'deleteItem'
},
deleteItem: function() {
app.trigger('item:delete', this.model);
}
}),
ItemsView = Mn.CollectionView.extend({
tagName: 'table',
childView: ItemView,
onShow: function(view) {
TweenMax.staggerFrom($(view).find('td'), 1, {
x: 100
}, 2);
}
}),
I have an initializer function, that listens for events above and does stuff through app.ItemController. It all works fine.
But now I want to add a region (counter region), that displays the total number of items in my collection. I need this to be a separate view ideally, because I will be displaying it in different places.
So I do this:
DisplayCounter = Mn.ItemView.extend({
template: _.template('Total: '+ app.Items.length),
}),
app.Items is an instance of Collection declared above. But even before instantiation of DisplayCounter, I get error:
Uncaught TypeError: Cannot read property 'length' of undefined.
Please help... :(
------------------------- E D I T ----------------------
I've achieved it, but it seems to be so complicated to do such a tiny thing.
Changed my collection like so:
Items = Backbone.Collection.extend({
model: Item,
url: 'api/items',
initialize: function() {
this.listenTo(this, 'add', function() {
app.trigger('collection:updated', this);
});
}
}),
and changed my DisplayCounter like this:
DisplayCounter = Mn.ItemView.extend({
template: _.template('Total: <%=length%>'),
templateHelpers: function() {
return {
length: this.lengthVariable || 0
}
},
initialize: function() {
app.on('collection:updated', function(params){
this.lengthVariable = params.length;
this.render();
}.bind(this));
}
}),
I can't believe there's no easier way to do this.. :/
The code that sets up DisplayCounter is being run before the code that puts an instance of Items into app.Items.
Even if you avoided this problem by assigning app.Items first, you'd still have a problem - the template property is only set once so you'd only ever see the length of app.Items at the time that you define DisplayCounter.
Rather than hard-coding the value directly into the template string, you should supply a value at render time. Mn.View.serializeData allows you to customise the data that is passed into the template function at render time:
DisplayCounter = Mn.ItemView.extend({
template: _.template('Total:: <%= itemCount %>),
serializeData: function() {
return { itemCount: app.Items.length }
}
}),
app.Items is not being defined.
In Marionette you can define which collection or model are your views going to use.
ItemsView = Mn.CollectionView.extend({
tagName: 'table',
childView: ItemView,
collection: myItems // An instance of your collection
onShow: function(view) {
TweenMax.staggerFrom($(view).find('td'), 1, {
x: 100
}, 2);
}
}),
So marionette is going to render one itemView per element in your collection. Then inside of your collection view this.collection is going to refer to the collection instance. So this.collection.length will have what you need.
And in your ItemView you can get the corresponding model by using this.model
So for some reason navigate won't work in one of my views. I'm doing everything in one file for now, so that may be the problem. Also I know the code is horrible, I'm just messing around with backbone right now.
EDIT: I put a console.log() in MarketingPage's function route and it never gets called, so there must be something wrong with the view.
Also, this is the error I'm getting from chrome dev tools:
Error in event handler for 'undefined': IndexSizeError: DOM Exception 1 Error: Index or size was negative, or greater than the allowed value.
at P (chrome-extension://mgijmajocgfcbeboacabfgobmjgjcoja/content_js_min.js:16:142)
at null.<anonymous> (chrome-extension://mgijmajocgfcbeboacabfgobmjgjcoja/content_js_min.js:18:417)
at chrome-extension://mgijmajocgfcbeboacabfgobmjgjcoja/content_js_min.js:1:182
at miscellaneous_bindings:288:9
at chrome.Event.dispatchToListener (event_bindings:390:21)
at chrome.Event.dispatch_ (event_bindings:376:27)
at chrome.Event.dispatch (event_bindings:396:17)
at Object.chromeHidden.Port.dispatchOnMessage (miscellaneous_bindings:254:22)
Here's my code:
/*global public, $*/
window.public = {
Models: {},
Collections: {},
Views: {},
Routers: {
},
init: function () {
console.log('Hello from Backbone!');
}
};
var App = Backbone.Router.extend({
routes: {
'': 'index',
'register': 'route_register',
},
index: function(){
var marketing_page = new MarketingPage();
},
route_register: function(){
var register_view = new RegisterView();
}
});
window.app = new App();
var User = Backbone.Model.extend({
url: '/user',
defaults: {
email: '',
password: ''
}
});
var MarketingPage = Backbone.View.extend({
initialize: function(){
this.render();
},
render: function(){
var template = _.template($("#marketing-page").html());
$('.search-box').after(template);
},
events: {
'dblclick': 'route'
},
route: function(e){
e.preventDefault();
console.log("In route");
window.app.navigate('register', {trigger: true});
this.remove();
}
});
var RegisterView = Backbone.View.extend({
initialize: function() {
this.render();
},
render: function(){
var template = _.template($("#register-template").html());
$('.search-box').after(template);
}
});
$(document).ready(function () {
Backbone.history.start();
});
When I type host/#register into the browser directly, the register view gets rendered, but no matter what I do the click event won't seem to work...
Since the handler function route isn't being called, it's likely that the event delegation isn't working.
One thing to note is that the event handling that is set up in a Backbone View is scoped to only that view's el. I don't see where yours is set up explicitly, so it might be creating an empty div, then handling events inside that empty div (which you don't want).
One trick I use for quick prototypes is to set the view's el with a jQuery selector pointing to something that exists on the page already, then in the render, show it with a .show().
Since you're not really doing that, here's one thing you could try. What we're doing is setting the $el content and then calling delegateEvents to make sure that the events and handlers are being bound.
var MarketingPage = Backbone.View.extend({
initialize: function(){
this.render();
},
render: function(){
this.$el.html(_.template($("#marketing-page").html()));
$('.search-box').after(this.$el);
this.delegateEvents();
},
events: {
'dblclick': 'route'
},
route: function(e){
e.preventDefault();
console.log("In route");
window.app.navigate('register', {trigger: true});
this.remove();
}
});
Backbone.js views delegateEvents do not get bound (sometimes)
http://backbonejs.org/#View-delegateEvents
I've looked everywhere for an answer but wasn't satisfied with what I've found.
The issue is, I'm doing a tutorial from Addy Osmani to make a 'Todo' app in Backbone, but when I look at the console, I get an error saying that this.model is undefined.
I even tried this SO answer Backbone model error displayed in console, but I still get the same error. Please tell me what is wrong.
By the way, what are this.model or this.collection? I've got an idea that they refer to Backbone.Model and Backbone.Collection but how do they work? I'm asking this because in another tutorial this.collection and this.model.models were also undefined, when I've clearly defined the Model and Collection.
Many Thanks
JS:
//Model
var Todo = Backbone.Model.extend({
defaults: {
title: 'Enter title here',
completed: true
},
validate: function(attrs) {
if (attrs.title === undefined) {
return 'Remember to enter a title';
}
},
initialize: function() {
console.log('This model has been initialized');
this.on('change:title', function() {
console.log('-Title values for this model have changed');
});
this.on('invalid', function(model, error) {
console.log(error);
});
}
});
//View
var TodoView = Backbone.View.extend({
el: '#todo',
tagName: 'li',
template: _.template($('#todoTemplate').html()),
events: {
'dbclick label': 'edit',
'click .edit': 'updateOnEnter',
'blur .edit': 'close'
},
initialize: function() {
_.bindAll(this, 'render');
this.render();
},
render: function() {
this.$el.html(this.template(this.model.toJSON()));
this.input = this.$('.edit');
console.log(this.model.toJSON());
return this;
},
edit: function() {
//do something...
},
close: function() {
//do something...
},
updateOnEnter: function() {
//do something...
}
});
var todoview = new TodoView();
console.log(todoview.el);
//Collection
var TodoList = Backbone.Collection.extend({
model: Todo
});
You need to instantiate a Model or Collection and pass it to your View. Otherwise, when the render method is called on your TodoView, this.model will be null.
For example, try rearranging the last few lines of your code like this:
//Collection
var TodoList = Backbone.Collection.extend({
model: Todo
});
var todos = new TodoList();
var todoview = new TodoView({model: todos});
From that point onward, you can modify todos (which is a Collection) and your view can listen to todos' events and re-render accordingly.
The answer in the other question is the answer to your question: you're not passing the model to the view when you instantiate the view.
var model = new Todo();
var todoview = new TodoView({model: model});
When you pass an object to a view's constructor, it looks for certain keys and attaches them directly to the view.
You can see which by looking at Backbone's source and searching for viewOptions.
That's how you get the this.model and this.collection automatically attached to the view's this.
You didn't say, but I assume the error you are getting is occurring in the render() method.
Your problem is that you define a new type of model (var Todo = Backbone.Model.extend({...) however you never instantiate it, nor do you pass the model to the todoview constructor.
So at the very least you need to do:
var todomodel = new Todo();
var todoview = new TodoView({
model: todomodel
});
I have a web application using BackboneJS. In this application, I have a LayoutView.js file in which there is a Backbone View (called LayoutView). LayoutView has other functions (methods) that call other views. I am fetching some data in the initialize function of LayoutView, and I need to get this same data (model) in another view and work (update/delete) on it. Below is how I am passing data from LayoutView to myView:
var LayoutView = Backbone.View.extend({
el: $("#mi-body"),
initialize: function () {
var that = this;
this.ConfigData = new Configurations(); //Configurations is a collection
this.ConfigData.fetch({
success: function () {
alert("success");
},
error: function () {
alert("error");
}
});
this.render();
Session.on('change:auth', function (session) {
var self = that;
that.render();
});
},
render: function () {
// other code
},
events: {
'click #logout': 'logout',
'click #divheadernav .nav li a': 'highlightSelected'
},
myView: function () {
if (Session.get('auth')) {
this.$el.find('#mi-content').html('');
this.options.navigate('Myview');
return new MyLayout(this.ConfigData);
}
}
});
Still, I do not know how to "get"/access this data as my current data/model/collection (I am not sure which term is correct) in myView and work on it using Backbone's "model.save(), model.destroy()" methods. Also, whenever an edit/delete happens, the data of ConfigData should be modified and the update should reflect in the html displayed to the user.
Below is the code from MyView:
var MyView = Backbone.View.extend({
tagName: 'div',
id: "divConfigurationLayout",
initialize: function (attrs) {
this.render();
},
render: function () {
var that = this;
},
events: {
"click #Update": "update",
"click #delete": "delete"
},
update: function(){
//code for updating the data like model.save...
},
delete: function(){
//code for deleting the data like model.destroy...
}
});
Now the data I passed is in attrs in the initialize function. How to get this done..?
The syntax for instantiating a Backbone view is new View(options) where options is an Object with key-value pairs.
To pass a collection to your view, you'd instantiate it like so:
new MyLayout({
collection : this.configData
});
Within your view, this.collection would refer to your configData collection.
I am working on a contact bar which renders all contacts of a user in a html list.
What I have:
UserModel - This is a simple Backbone.Model with username and email
UserCollection - This is used as the contact list
ContactsView - This is the ul contact list
ContactView - This is a single contact model rendered as li
I am currently breaking my head about a solution how (and where) I can fetch my UserCollection and how I pass the single models down to a single ContactView item.
Specific hurdles are:
Where should I fetch, store the UserCollection
How do I render the contact list
How do I render the contact items
How do I prevent fetch({ success: callback }) from breaking my code structure
My current code is this:
entrance point:
// create a new instance of the contact list view
var view = new ContactsView();
// insert the rendered element of the contact list view in to the dom
$('div.contacts-body').html(view.render().el);
view.fetch({ success: view.loadContacts });
ContactsView:
define(
['jquery', 'underscore', 'backbone', 'text!templates/conversations/contacts.html', 'collections/users', 'views/conversations/contact'],
function($, _, Backbone, ContactsTemplate, UserCollection, ContactView) {
var ContactsView = Backbone.View.extend({
tagName: "ul",
className: "contacts unstyled",
attributes: "",
// I am feeling uneasy hardcoding the collection into the view
initialize: function() {
this.collection = new UserCollection();
},
// this renders our contact list
// we don't need any template because we just have <ul class="contacts"></ul>
render: function() {
this.$el.html();
return this;
},
// this should render the contact list
// really crappy and unflexible
loadContacts: function() {
this.collection.each(function(contact) {
// create a new contact item, insert the model
var view = new ContactView({ model: contact });
// append it to our list
this.$el.append(view.render().el);
});
}
});
return ContactsView;
});
ContactView
define(
['jquery', 'underscore', 'backbone', 'text!templates/conversations/contact.html'],
function($, _, Backbone, ContactTemplate) {
var ContactView = Backbone.View.extend({
tagName: "li",
className: "contact",
attributes: "",
template:_.template(ContactTemplate),
initialize: function() {
this.model.bind('change', this.render, this);
this.model.bind('destroy', this.remove, this);
},
render: function() {
this.$el.html(this.template(this.model.toJSON()));
return this;
}
});
return ContactView;
});
Could somebody help me about my four hurdles.
Good example links are welcome. I oriented my code style at the todos list unfortunatly the todos list isn't that advanced...
UPDATED CODE:
define(
['jquery', 'underscore', 'backbone', 'text!templates/conversations/contacts.html', 'collections/users', 'views/conversations/contact'],
function($, _, Backbone, ContactsTemplate, UserCollection, ContactView) {
var ContactsView = Backbone.View.extend({
tagName: "ul",
className: "contacts unstyled",
attributes: "",
events: {
},
initialize: function() {
this.collection = new UserCollection();
this.collection.on('reset', this.render);
this.collection.fetch();
},
render: function() {
// in chromium console
console.log(this.el); // first: html, second: undefined
console.log(this.$el); // first: html in array, second: undefined
this.$el.empty(); // error on the called that this.$el is undefined
this.collection.each(function(contact) {
var view = new ContactView({ model: contact });
this.$el.append(view.el);
}.bind(this));
return this;
}
});
return ContactsView;
Can it be that reset is triggering this.render twice?
First of all: why do you fetch the view? Backbone views do not have a fetch method..
1 The correct place to fetch your UserCollection would be inside the view's initialize method:
initialize: function() { // ContactsView
_.bindAll(this, 'render', 'otherMethodName', ...); // Bind this to all view functions
...
this.collection.on('reset', this.render); // bind the collection reset event to render this view
this.collection.fetch();
...
}
Now you fetch the contacts exactly when you need them. Next step is to render the collection.
2 Binding to the reset event makes your loadContacts method obsolete and we can do that in the render function:
render: function() {
this.$el.empty(); // clear the element to make sure you don't double your contact view
var self = this; // so you can use this inside the each function
this.collection.each(function(contact) { // iterate through the collection
var contactView = new ContactView({model: contact});
self.$el.append(contactView.el);
});
return this;
}
Now you render your contactlist inside the render method, where it should be done.
3 The ContactView actually looks good.
Just make the item to render itself in the initialize method, so you don't have to make useless calls in the ContactsView's render method and clutter up your code. Also bindAll here as well.
initialize: function() { // ContactView
_.bindAll(this, 'render', 'otherMethodName', ...);
...
this.render(); // Render in the end of initialize
}
I have no idea what you are asking in here, but I think the best way is not to use success callbacks. The collections and models trigger events whenever something is done to them, so tapping onto them is much more robust and reliable than success callbacks. Check out the catalog of events to learn more. The Wine Cellar tutorial by Christophe Coenraets is has an excellent example of this kind of listview-listitemview arrangement.
Hope this helps!
UPDATE: Added _.bindAlls to fix the problem with this in a event bound render call. Some info on binding this.
NOTE: all the code is simplified and no tested
When I have all the elements structure defined, as you have, with all the Models, Collections and Views implemented then I implement a Loader which is in charge of trigger the fetching and rendering actions.
First of all I need to expose the classes definition from the outside something like this:
// App.js
var App = {}
// ContactsCollection.js
$(function(){
var App.ContactsCollection = Backbone.Collection.extend({ ... });
});
// ContactsView.js
$(function(){
var App.ContactsView = Backbone.View.extend({ ... });
});
// and so on...
And then I implement what I call the Loader:
// AppLoad.js
$(function(){
// instantiate the collection
var App.contactsCollection = new App.ContactsCollection();
// instantiate the CollectionView and assign the collection to it
var App.contactsView = new App.ContactsView({
el: "div.contacts-body ul",
collection: App.contactsCollection
});
// fetch the collection the contactsView will
// render the content authomatically
App.contactsCollection.fetch();
});
Another changes you have to do is configure the ContactsView in a way that respond to the changes in the App.contactsCollection because as the fetch() is asynchronous you can call render() when the collection is still not loaded, so you have to tell to the CollectionView to render it self when the Collection is ready:
var ContactsView = Backbone.View.extend({
initialize: function( opts ){
this.collection.on( 'reset', this.addAll, this );
this.collection.on( 'add', this.addOne, this );
// ... same with 'remove'
},
addOne: function( model ){
var view = new App.ContactView({ model: contact });
this.$el.append( view.render().el );
},
addAll: function(){
this.collection.each( $.proxy( this.addOne, this ) );
}
});
You have to require your js files in the proper order:
App.js
Your Models, Collections, Views
AppLoad.js
With this system you obtain:
External access to your collection in case you need to access it from another place.
External control of the CollectionView.el with is better for decoupling and testing.
The CollectionView will respond to changes in the Collection authomatically
Note: If you use Router you can move the AppLoad.js logic to there.