From the backbone documentation:
All views have a DOM element at all times (the el property), whether they've already been inserted into the page or not.
I have following very simple javascript file:
CBBItem = Backbone.Model.extend(
{
});
CBBTrackItem = Backbone.View.extend(
{
template: _.template("<span><%= title %></span>"),
initialize: function()
{
_.bindAll(this, "render");
},
render: function()
{
$(this.el).html(this.template(this.model.toJSON()));
return this;
}
});
And a html page like this:
<script type="text/javascript">
$(function()
{
var itm1 = new CBBItem({ title: 'track 1'});
var itmUI1 = new CBBTrackItem({ model: itm1, id: "kzl" });
itmUI1.render();
});
</script>
<body>
<div id="kzl"></div>
</body>
My view item doesn't want to render although there is a created div on the page. I can trick the situation in many ways. For example doing something like this
var itm1 = new CBBItem({ title: 'track 1'});
var itmUI1 = new CBBTrackItem({ model: itm1, id: "big_kzl" });
$(itmUI1.render().el).appendTo("#kzl");
But, why is the main case not working?
Here's one possibility: you aren't setting the el for the view, so it doesn't know what to do with your template. Could you modify your view-calling code to look like this?
var itmUI1 = new CBBTrackItem({
model: itm1,
id: "big_kz1",
el: "#kz1"
});
itmUT1.render();
Alternatively, you could set the el value within the initialize of the view if the value never varies. The advantage to doing so is that callers of the view don't have to know this information and thus the view is more self-contained.
If the document already has the element you want to use as el for a particular view, you have to manually set that dom element as the el attribute when the view is initialized. Backbone provides you no shortcut for doing that.
I've experienced problems when passing values like ID and events in during construction as opposed to defining them during extension. You may want to check and see if that's the difference you're looking for.
Related
I want to do a simple application using backbonejs with mustache template. Can you give me a sample program??
New node file:
var Person = Backbone.Model.extend({
defaults: {
name: 'Guest Worker',
}
});
var PersonView = Backbone.View.extend({
tagName: 'li',
initialize: function(){
_.templateSettings = {
interpolate: /\{\{(.+?)\}\}/g
};
this.render();
},
render: function(){
var template1 = _.template("Hello {{ name }}!");
this.$el.html( this.template1(this.model.toJSON()));
}
});
This is my js code.
Mustache template engine doesn't work this way. Here's a small example from the documentation :
var view = {
title: "Joe",
calc: function () {
return 2 + 4;
}
};
// output will then contain processed html
var output = Mustache.render("{{title}} spends {{calc}}", view);
Anyway, i would recommend you using Handlebars (http://handlebarsjs.com/) instead of Mustache. It's almost the same syntax (and it has partials as Mustache does), but far more powerful thanks to its helpers.
Finally, you should use something to precompile your templates. You can either use handlebars's one (http://handlebarsjs.com/precompilation.html) or another one like Brunch, or Grunt.
[Edit] OK, let's try to elaborate a bit... I won't give you any complete example (i don't have one right now, and it wouldn't teach you anything), but the one i posted above should be sufficient to understand Mustache basics.
Now you have to find a way to precompile your templates, here's an answer with some clues : How to load templates with Hogan.JS from an external file?
While an underscore template is set like this in Backbone.js:
template: _.template(...)
A mustache template is set like this:
template: Mustache.render.bind(null,<template>)
//Mustache.render(template,view,[partials])
//a partial function is created because this.template should be a function
//<function>.bind() creates the partial function
don't do these:
template: Mustache.to_html(<template>) // deprecated
// or
template: Mustache.to_html.bind(null,<template>) // deprecated
// Use Mustache.render() and not Mustache.to_html()
I am using twitter bootstrap link. When the user clicks the link a bootstrap modal appears.
Now because of some bootstrap technical difficulties in modal rendering i need to seperate the link and put the modal out the navbar div.
So consider i have two separate div
<div id="linkDiv">
</div>
and
<div id="modalDiv">
</div>
Now i have only one View which makes a call to the server to get the collection
app.View.FriendRequestListView = Backbone.View.extend( {
templateModalLink: _.template($('#link').html()),
templateModal: _.template($('#modal').html()),
tagName: 'div',
initialize: function(){
this.friendRequestCollection = new app.Collection.FriendRequestCollection();
this.friendRequestCollection.bind("reset", this.render, this);
this.friendRequestCollection.fetch();
},
render: function() {
$(this.el).html(this.templateModalLink({
friendRequestCollection: this.friendRequestCollection}));
return $(this.el);
},
});
Than i can render only one div like following
var list = new app.View.FriendRequestListView();
$('#linkDiv').html(list.$el);
My question is , Is it possible to render two templates at the same time and add the two templates to different DIV like for example in my case i want to get update
templateModalLink template to linkDiv and templateModal template to modalDiv with the collection I am getting from the server.
You have to instantiate the collection before app.View.FriendRequestListView(s) and pass app.View.FriendRequestListView(s) the collection:
var friendRequests = new app.Collection.FriendRequestCollection();
friendRequests.fetch(
success: function(collection, response, options) {
var list1 = new app.View.FriendRequestListView({collection: collection});
var list2 = new app.View.FriendRequestListView({collection: collection});
$('#linkDiv').html(list1.$el);
$('#modalDiv').html(list2.$el);
}
);
I'm playing around with backbone.js for the first time, but can't get the events to fire properly. Can somebody explain what I'm doing wrong?
Much appreciated!
in app.js loaded at the bottom of my html:
var Discussion = Backbone.Model.extend({
defaults: {
id: null,
title: 'New discussion'
},
urlRoot: '/api/discussion'
});
var DiscussionCollection = Backbone.Collection.extend({
model: Discussion,
url: '/api/discussion'
});
var DiscussionView = Backbone.View.extend({
events: {
'click .btnCreateDiscussion': 'create',
'keypress #discussion_title': 'create'
},
initialize: function(){
//this.$el = $("#form_discussion");
this.template = _.template( $('#discussion-template').html() );
},
render: function(){
console.log("rendering");
return this;
},
create: function(){
console.log('creating a new discussion')
}
});
var discussionView = new DiscussionView({ el: $("#form_discussion"), model: Discussion });
html:
<form action="" id="form_discussion" method="post">
<label for="discussion_title">Discussion Title</label>
<input type="text" id="discussion_title" name="discussion_title" />
<input class="btnCreateDiscussion" type="button" value="Create Discussion">
<script type="text/template" id="discussion-template">
<h1><%= title %></h1>
</script>
It seems to work fine: http://jsfiddle.net/Jbahx/. (check your backbone & underscore versions, and make sure the DOM is initialized)
About what you're doing wrong though:
model: Discussion when instantiating your view. You have to give the view an instance of a model, not a class. If you give the view a model (optional), it's generally because you want to represent the data of a particular instance.
Your render method is never called, but it's useless at the moment so that's not that big a problem.
this.template = _.template( $('#discussion-template').html() ); in the initialize method. Put this as a property of the view when extending so it'll be put in the prototype of your view (even if it seems to be a singleton here): template: _.template( $('#discussion-template').html() ),.
The problem was jQuery. The most recent 1.x release didn't work, but using the most recent 2.x release fixes the problem. It would be useful if anyone could explain why we should only use 2.x in this case?
First of all, you must call Backbone.View.prototype.initialize in your overriden method to let Backbone initialize event listeners:
initialize: function(){
//this.$el = $("#form_discussion");
this.template = _.template( $('#discussion-template').html() );
Backbone.View.prototype.initialize.call(this)
},
Second, render view in initialize - it isn't best practice. Use for this separate render method.
So I'm checking out the changes related to the latest backbone/underscore version. Prior I have a project running with BB 0.5.2 and underscore 1.1.7. I'm noticing something strange with regards to defining a template property within a view in the new version, which gives me reservations in going forward with upgrading.
In my current version I would define a view as such:
var MyView = Backbone.View.extend({
template: _.template($('#exampleTemplate').html()),
initialize: function() {...},
render: function() { $(this.el).html(this.template(someObjectParam)); },
});
However, if I attempt to work in the same manner, using a simplified todo clone attempt as an example, I setup an html with an inline script template as such:
<script>
$(document).ready(function() {
app.init();
});
</script>
<script type="text/template" id="itemViewTemplate">
<div class="item">
<input type="checkbox" name="isComplete" value="<%= item.value %>"/>
<span class="description"><%= item.description %></span>
</div>
</script>
In my included JS file I have:
var ItemView = Backbone.View.extend({
el: 'body',
// Below causes error in underscore template, as the jquery object .html() call
// returns null. Commenting will allow script to work as expected.
templateProp: _.template($('#itemViewTemplate').html()),
initialize: function() {
// Same call to retrieve template html, returns expected template content.
console.log($('#itemViewTemplate').html());
// Defining view template property inside here and calling it,
// properly renders.
this.template = _.template($('#itemViewTemplate').html());
this.$el.html(this.template({item: {value: 1, description: 'Something'}}));
},
});
var app = {
init: function() {
console.log('Fire up the app');
var itemView = new ItemView();
}
}
So I'm left confused as to why defining the template property directly causes the call to retrieve the template html to return a null value, thus breaking the attempt to define an underscore template object (mouthful). However, if the definition is done within the initialize function, the call to retrieve the template html properly finds the template so its contents can be passed to the underscore template. Anyone see what I'm potentially missing?
Thanks in advance!
If this:
var ItemView = Backbone.View.extend({
//...
templateProp: _.template($('#itemViewTemplate').html()),
//...
});
is failing because $('#itemViewTemplate').html() is null, then you have a simple timing problem: you're trying to read the content of #itemViewTemplate before it exists. Your old version should suffer from exactly the same problem.
Either make sure everything is loaded in the right order (i.e. your views after your template <script>s) or compile the template in your view's initialize. You can check for the templateProp in your view's prototype and only compile it on first use if you want:
initialize: function() {
if(!this.constructor.prototype.template)
this.constructor.prototype.template = _.template($('#itemViewTemplate').html());
//...
}
Demo: http://jsfiddle.net/ambiguous/HmP8U/
I have a few different problems going on, I hope though this example is easy to follow. The code uses an HTML template with elements hidden by default (using CSS). The Backbone View uses data in a Model to display appropriate values OR hide the UI element if no value is present in the Mode.
Given a template where everything is hidden by default (using CSS), for example:
<script type="text/template" id="Person-Template">
<span class="fname" title="FirstName"></span>
<span class="lname" title="LastName"></span>
<span class="age" title="Age"></span>
</script>
To hide each UI element the CSS is:
span.fname,
span.lname,
span.age {
display:none;
}
My Backbone.js Model would therefore be:
PersonModel = Backbone.Model.extend({
defaults: {
fname: undefined,
lname: undefined,
age: undefined
}
});
The View (simplified) would be:
PersonView = Backbone.View.extend({
tagName: 'div',
initialize: function() {
this.model.on("fname", this.updateFName, this);
this.model.on("lname", this.updateLName, this);
this.model.on("age", this.updateAge, this);
},
updateFName: function() {
// Pseudo code
Get 'new' value from Model
Obtain reference to DOM element span.fname
Update span.fname
if (model value is empty) {
Hide UI element.
}
},
updateLName: function() {
// Same as above
},
updateAge: function() {
// Same as above
},
render: function() {
// Get model values to display
var values = {
FirstName : this.model.get('fname'),
LastName : this.model.get('lname'),
Age: this.model.get('age'),
};
// Load HTML template
var template = $('#Person-Template').html();
// Populate template with values
var t = _.template(template, values);
// Show / hide UI elements
this.updateFname();
this.updateLName();
this.updateAge();
}
}
Finally, the question: It seems hacky calling each updateXYZ() method from render() just to determine whether the UI element should be set to hidden or visible. I have a lot of attributes in my model and the code just seems a little absurd really.
I have been told on SO that the View should not be responsible for determining what should or should be displays. My questions is, well then what is responsible? The user may perform some (valid) aciton which clears the First Name, in which case I don't want my View displaying 'First name:' followed by no value.
First of all, you don't need to build your values by hand, just use toJSON:
var values = this.model.toJSON();
Then, you have to add your filled in template to your view's el:
this.$el.html(_.template(template, values));
and your template should probably include something to display in your template:
<script type="text/template" id="Person-Template">
<span class="fname" title="FirstName">F: <%= fname %></span>
<span class="lname" title="LastName">L: <%= lname %></span>
<span class="age" title="Age">A: <%= age %></span>
</script>
You don't separate functions for each of the three parts, you could just loop through them in your render:
_(values).each(function(v, k) {
var m = _(v).isUndefined() ? 'hide' : 'show';
this.$('.' + k)[m]();
}, this);
Now back to your events. There is no such thing as an "fname" event unless you've added a custom one. But there's no need for that, the model will trigger "change" and "change:fname" events when the fname is changed; you only need to care about "change" though:
initialize: function() {
_.bindAll(this, 'render');
this.model.on("change", this.render);
},
I've also bound render to your view instance using _.bindAll so that you don't have to worry about the third argument to this.model.on.
Now you have something that works: http://jsfiddle.net/ambiguous/46puP/
You can also push the "should this be displayed" logic into the template:
<script type="text/template" id="Person-Template">
<% if(fname) { %><span class="fname" title="FirstName">F: <%= fname %></span><% } %>
<% if(lname) { %><span class="lname" title="LastName">L: <%= lname %></span><% } %>
<% if(age) { %><span class="age" title="Age">A: <%= age %></span><% } %>
</script>
and simplify your render:
render: function() {
var values = this.model.toJSON();
var template = $('#Person-Template').html();
this.$el.html(_.template(template, values));
return this;
}
Demo: http://jsfiddle.net/ambiguous/W9cnJ/
This approach would probably be the most common and there's nothing wrong with it. I think you're misunderstanding what the previous answer was trying to tell you. The template chooses what pieces of information to display through <%= ... %> already so there's no good reason that it shouldn't see if fname, for example, is set before trying to display it. Depending on the nature of your data, you might want to use if(!_(fname).isUndefined()) and such in your template but a simple truthiness check is probably fine; the age might be an issue in some cases though so you might want to be a bit stricter with that.