Can't display data using Handlebars template and BackboneJS - backbone.js

I have been trying to display some data(a json object with only three properties) by fetching it from server (2 lines of php code). To fetch and display that data in html page I've used BackboneJS and Handlebars template respectively. Here is the javascript code
var User = Backbone.Model.extend({
urlRoot:"getUser/"
});
var UserView = Backbone.View.extend({
el:$("#user"),
initialize: function(){
this.model.bind("change", this.render());
},
render: function(){
var templateSource = $("#user-temp").html();
var template = Handlebars.compile(templateSource);
$(this.el).html(template(this.model));
var newDate = new Date();
console.log("in UserView render :: " + newDate.getTime());
console.log(this.model.toJSON());
//var pp = "nothing";
}
});
var UserRouter = Backbone.Router.extend({
routes:{
"":"userDetails"
},
userDetails:function(){
//var newUser = new User({id:1});
var newUser = new User();
var userView = new UserView({model:newUser});
var newDate = new Date();
newUser.fetch({
success:function(){
console.log("in router :: " + newDate.getTime());
console.log(userView.model.toJSON());
}
});
}
});
Handlebars template in index.html page
<div id="user"></div>
<script id="user-temp" type="text/x-handlebars-template">
<div>
ID {{attributes.id}}
Name {{attributes.name}}
Age {{attributes.age}}
</div>
</script>
PHP code
$user = array("name"=>"Arif","id"=>"1","age"=>"100");
echo json_encode($user);
Now the problem is I can't see the data ($user) i'm sending from server in index.html page, in console (google chrome) i've rather found this
in UserView render() :: 1350880026092
Object
__proto__: Object
in router :: 1350880026097
Object
age: "100"
id: "1"
name: "Arif"
__proto__: Object
(The BIG numbers in console is time in milliseconds.)
But If I change the code for console output (just showing the model)
(in UserView render() function)
console.log(this.model);
(in UserRouter userDetails() function)
console.log(userView.model);
Then the console looks like this
in UserView render :: 1350881027988
child
_changing: false
_escapedAttributes: Object
_pending: Object
_previousAttributes: Object
_silent: Object
attributes: Object <<======
age: "100"
id: "1"
name: "Arif"
__proto__: Object
changed: Object
cid: "c0"
id: "1"
__proto__: ctor
in router :: 1350881027995
child
_changing: false
_escapedAttributes: Object
_pending: Object
_previousAttributes: Object
_silent: Object
attributes: Object <<======
age: "100"
id: "1"
name: "Arif"
__proto__: Object
changed: Object
cid: "c0"
id: "1"
__proto__: ctor
Here i can see the attributes (arrow marks <<====== )
So what am i doing wrong? Am i missing some basic concepts here? By the way, I'm new to Handlebars and BackboneJS. Moreover its my first question in stackoverflow, so if you think the info i've given isn't enough, please feel free to ask what further info you need.
Thanks in advance.

You bind your model to this.render() which you means you execute your render function and then bind your model to whatever render returns (nothing, in your case).
Try
initialize: function(){
_.bindAll(this, 'render'); // guarantees the context for render
this.model.bind("change", this.render);
}
or, with a more up to date syntax (see the changelog for 0.9.0 http://backbonejs.org/#changelog, bind and unbind have been renamed to on and off for clarity)
initialize: function(){
_.bindAll(this, 'render');
this.model.on("change", this.render);
}

Related

Getting view to update on save using Backbone.js

I am learning Backbone.js and as a trial project I am creating a little WordPress user management application. So far my code shows a listing of all WordPress users and it has a form which enables you to add new users to the application.
This all works fine however when you add a new user the listing of users doesn't update automatically, you need to refresh the page to see the new user added which isn't ideal and defeats one of the benefits of Backbone.js!
I have a model for a user and then a collection which compiles all the users. I have a view which outputs the users into a ul and I have a view which renders the form. How do I make my code work so when the .save method is called the view which contains the users updates with the new user? Or is there another way to approach this?
//define the model which sets the defaults for each user
var UserModel = Backbone.Model.extend({
defaults: {
"username": "",
"first_name": "",
"last_name": "",
"email": "",
"password": "",
},
initialize: function(){
},
urlRoot: 'http://localhost/development/wp-json/wp/v2/users'
});
//define the base URL for ajax calls
var baseURL = 'http://localhost/development/wp-json/wp/v2/';
//function to define username and password
function authenticationDetails(){
var user = "myUserName";
var pass = "myPassword";
var token = btoa(user+':'+pass);
return 'Basic ' + token;
}
//add basic authorisation header to all API requests
Backbone.$.ajaxSetup({
headers: {'Authorization':authenticationDetails()}
});
//create a collection which returns the data
var UsersCollection = Backbone.Collection.extend(
{
model: UserModel,
// Url to request when fetch() is called
url: baseURL + 'users?context=edit',
parse: function(response) {
return response;
},
initialize: function(){
}
});
// Define the View
UserView = Backbone.View.extend({
model: UserModel,
initialize: function() {
// create a collection
this.collection = new UsersCollection;
// Fetch the collection and call render() method
var that = this;
this.collection.fetch({
success: function () {
that.render();
}
});
},
// Use an external template
template: _.template($('#UserTemplate').html()),
render: function() {
// Fill the html with the template and the collection
$(this.el).html(this.template({ users: this.collection.toJSON() }));
return this;
},
});
var userListing = new UserView({
// define the el where the view will render
el: $('#user-listing')
});
NewUserFormView = Backbone.View.extend({
initialize: function() {
this.render();
},
// Use an external template
template: _.template($('#NewUserTemplate').html()),
render: function() {
// Fill the html with the template and the collection
$(this.el).html(this.template());
return this;
},
events: {
'click .create-user':'addNewUser'
},
addNewUser: function(){
var newFirstName = $('.first-name').val();
var newLastName = $('.last-name').val();
var newEmail = $('.email').val();
var newPassword = $('.password').val();
var newUserName = newFirstName.toLowerCase();
var myNewUser = new UserModel({username:newUserName,first_name:newFirstName,last_name:newLastName,email:newEmail,password:newPassword});
console.log(myNewUser);
myNewUser.save({}, {
success: function (model, respose, options) {
console.log("The model has been saved to the server");
},
error: function (model, xhr, options) {
console.log("Something went wrong while saving the model");
}
});
}
});
var userForm = new NewUserFormView({
// define the el where the view will render
el: $('#new-user-form')
});
All backbone objects (models, collections, views) throw events, some of which would be relevant to what you want. Models throw change events when their .set methods are used, and Collections throw add or update events... a complete list is here.
Once you know which events are already being thrown, you can listen to them and react. For example, use listenTo - in your view's initialize, you can add:
this.listenTo(this.collection, 'add', this.render);
That will cause your view to rerender whenever a model is added to your collection. You can also cause models, collections, whatever, to throw custom events using trigger from anywhere in the code.
EDIT: For the specific case of getting your user listing view to rerender when a new user is added using the form, here are the steps you can take... In the initialize method of your UserView, after the initialize the collection, add:
this.listenTo(this.collection, 'add', this.render);
Then in your form view... assuming you want to wait until the save is complete on your server, in the addNewUser method, in the success callback of your save, add:
userlisting.collection.add(model);
This will work, since the instance of your UserView is in the global scope. Hope this one works for you!

Add model to collection after fetching it

Im having trouble figuring out how to populate a model's attributes from the server and then add the populated model to a collection and have that collection rendered by a view. Here's the code I have:
var movieDetails = new cinephile.Models.MovieDetailsModel({ id: movie.get('id') });
this.collection.add(movieDetails);
Inside of the MovieDetailsModel:
cinephile.Models.MovieDetailsModel = Backbone.Model.extend({
url: function()
{
return '/cinephile/api/index.php?action=getMovieDetails&movieId=' + this.id;
},
initialize: function()
{
this.fetch();
}
});
And this.collection is just a collection with the model set to be a cinephile.Models.MovieDetailsModel
I am listening for items to be added to the collection and when they are, the following is executed:
displayMovie: function(movie)
{
var view = new cinephile.Views.MovieView({
model: movie,
className: 'movie clearfix',
template: JST['app/scripts/templates/MovieView.ejs'],
});
this.$("#my-movies").append(view.el);
},
MovieView looks like this:
cinephile.Views.MovieView = Backbone.View.extend({
initialize: function(options)
{
this.template = options.template;
this.render();
},
render : function()
{
this.$el.html(this.template(this.model.attributes));
return this;
},
});
The problem I have is that the template I'm using is trying to access an attribute of the model that is undefined. Im pretty sure it's undefined because the MoveDetailsModel hasn't finished fetching before the model is added to the collection and subsequently rendered to the view.
How can I solve this issue? I'd like to be able to create a MovieDetailsModel that takes in an id, use that id to get the movie details from the server and then add the populated model to a collection and then render that collection to the screen.
Any help is appreciated.
Backbone fetch returns a jqXHR object, which is a Deferred objects Promise.
When fetch is called, the attributes are not populated yet. Promise objects have a don
ejqXHR function, where a callback can be passed to be executed once the request is done.
I would recommend moving the fetch into another method not the constructor, because there You can return the jqXHR object and access its done function.
Here is an example:
var movieDetails = new cinephile.Models.MovieDetailsModel({ id: movie.get('id') });
var promise = movieDetails.fetch();
promise.done(function() {
var view = new cinephile.Views.MovieView({model: movieDetails});
view.render();
});

Backbone localstorage A "url" property or function must be specified

I am creating a small application based on a backbone example with the backbone-localstorage plugin.
When saving the data for a new model I always get the error "A "url" property or function must be specified"
After reading through several simular topics I'm still not able to find the cause for this.
Model:
directory.models.EmployeeCollection = Backbone.Collection.extend({
localStorage: new Backbone.LocalStorage("EmployeeCollection"),
model: directory.models.Employee,
store: directory.utils.store,
findByName: function(key) {
this.reset(this.store.findByName(key));
}
});
The view:
directory.views.newEmployeeView = Backbone.View.extend({
tagName: "div",
initialize: function() {
this.template = _.template(directory.utils.templateLoader.get('new-employee'));
},
events: {
"click .save": "saveEmployee"
},
render: function(eventName) {
$(this.el).html(this.template(this.model.toJSON()));
return this;
},
saveEmployee: function(event){
this.model.set({
firstName:$('#newFirstName').val(),
lastName:$('#newLastName').val(),
title:$('#newTitle').val(),
city:$('#newCity').val(),
officePhone:$('#newOfficePhone').val(),
cellPhone:$('#newCellPhone').val(),
email:$('#newEmail').val()
});
this.model.save();
window.history.back();
return false;
}
});
I think you need the new model to be a member of your collection before you attempt to persist it. Try creating a new instance of your collection and passing it to the view (probably in your router) like this:
new newEmployeeView({ collection: new EmployeeCollection() });
In your view you can use Backbone's create convenience method (see docs) to add a new instance of the model to the collection and persist it:
this.collection.create({
firstName:$('#newFirstName').val(),
lastName:$('#newLastName').val(),
title:$('#newTitle').val(),
city:$('#newCity').val(),
officePhone:$('#newOfficePhone').val(),
cellPhone:$('#newCellPhone').val(),
email:$('#newEmail').val()
});

Empty backbone collection/model at working API?

i try to fetch a record of a rails-api (same host) into my backbone collection. i have the following code:
// Models
App.GeeksModel = Backbone.Model.extend({
urlRoot: "/geeks",
idAttribute: "id"
});
// Collections
App.GeeksCollection = Backbone.Collection.extend({
url: "/geeks",
model: App.GeeksModel
});
in my router i have the following
// Router
App.GeekRouter = Backbone.Router.extend({
routes: {
"": "index"
},
initialize: function() {
console.log("router - init");
},
index: function() {
console.log("route - index");
var geekCollection = new App.GeeksCollection();
var mapView = new App.GeeksMapView({ el: $("#foo"), model: geekCollection });
geekCollection.fetch();
}
});
when browsing the url, the view loads correctly and at the server i see, that one entry is fetched from the database. but as soon as i check the model length in my view using
this.model.length
the collection is empty... any advice on this?
thanks
EDIT 1:
when changing the index router method to
var mapView = new App.GeeksMapView({ el: $("#map"), collection: geekCollection });
and e.g. check for the collection length in the views intialize method
...
initialize: function() {
this.render();
console.log(this.collection.length);
},
...
it retunes 0 as well... so nothing changed!
I believe you want to do collection.length or if accessing from the model - each model holds reference to collection in which it was created model.collection.length - if this is referencing to collection doing just this.length should be enough, if it's a model then this.collection.length will do it for you.
Models have no property length so should always be undefined unless you define it yourself.

populating nested collection with nested json

Solution
in my route
Myapp.Routes = Backbone.Router.extend({
init: function(){
user = new User();
user.fetch({user,
success: function(response){
user.classlist = new classes(response.attributes.classes);
});
}
});
I've got a serialized json array being returned from my server, and I am trying to put the nested objects into my nested collections.
This answer, I thought was going to get me there, but I'm missing something.
How to build a Collection/Model from nested JSON with Backbone.js
The json which I am trying to populate my nested model with is
{first_name: "Pete",age: 27, classes: [{class_name: "math", class_code: 42},{class_name: "french", class_code: 18}]}
I create my user model
MyApp.Models.Users = = Backbone.Model.extend({
initialize: function(){
this.classlist = new MyApp.Collections.ClassList();
this.classlist.parent = this;
}
});
I had tried to follow the example on the other page, and use
this.classlist = new MyApp.Collections.ClassList(this.get('classes'));
this.classlist.parent = this;
but this.get('classes') returns undefined.
I've also tried getting the classes array through this.attributes.classes, but that is also undefined.
------------updated to include re-initialize --------------------
The function where I am initializing the user and classes is in the User routes and is called re-initialize. I use this function to fetch the user and their classes and store the object.
re_initialize: function(id){
user = new MyApp.Models.User();
MyApp.editingClasses.url = 'classes/'+id;
MyApp.editingClasses.fetch({
success: function(response){
MyApp.editingClasses.parse(response);
}
});
new MyApp.Views.ClassesInput();
},
As you can see, I'm calling the parse explicitly in the success function, but it isn't adding the classes to the collection.
I can't include the 'collection' because for some reason I can't access it in backbone.
the user model, after getting returned to backbone includes the classes array, which I am trying to put into the ClassList collection.
The user model object copied from the javascript terminal looks like this.
attributes: Object
created_at: "2012-01-05T16:05:19Z"
id: 63
classes: Array[3]
0: Object
created_at: "2012-01-18T20:53:34Z"
id: 295
teacher_id: 63
class_code: 42
updated_at: "2012-01-18T20:53:34Z"
class_name: math
__proto__: Object
1: Object
2: Object
length: 3
__proto__: Array[0]
You can use the parse function to pre-process the server response:
MyApp.Models.Users = Backbone.Model.extend({
parse: function(response) {
var classesJSON = response.classes;
var classesCollection = MyApp.Collections.ClassList(classesJSON);
response.classes = classesCollection;
return response;
}
});
var user = new MyApp.Models.Users();
user.fetch();
// You should now be able to get the classlist with:
user.get('classes');
That said, the approach suggested in the other question should also work. It could be that when your initialize function is called, the model hasn't yet been populated with the data?
For example, if you're doing:
var user = new MyApp.Models.Users();
It won't have any attributes yet to give to the classlist collection. Could that be your problem?
Okay! you can maybe fetch the classes this way :
Model :
window.person = Backbone.Model.extend({
defaults: { }
});
Collection :
window.ClassesCollection = Backbone.Collection.extend({
model: person,
url: "http://your/url/data.json",
parse: function(response){
return response.classes;
}
});
Router :
window.AppRouter = Backbone.Router.extend({
routes: {
"" : "init"
},
init: function(){
this.classesColl = new ClassesCollection();
this.classesColl.fetch();
this.classesView = new ClassesView({collection: this.classesColl});
}
});
View : (for rendering every classes)
window.ClassesView = Backbone.View.extend({
el: $('...'),
template: _.template($("...").html()),
initialize: function() {
this.collection.bind("reset", this.render, this);
},
render: function(collection) {
_.each( collection.models, function(obj){
...
//obj.get('class_name') or obj.get('class_code')
...
}, this );
...
return this;
}
});

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