I'm trying to use the collection.reset() and am not getting the results i am expecting in the UI. The response returns 2 results, which is as expected. When i inspect my collection, it always tells me i have 2 results, which also is correct.
However, in my html output, it just keeps appending the 2 newly fetch rows to the table.
initialize: function() {
_.bindAll(this,'buildRows','refreshTable');
this.template = _.template(maintmpl);
this.collection = txnList;
this.collection.bind("all", this.buildRows, this);
this.collection.on("reset", this.refreshTable, this);
this.collection.fetch();
},
events: {
"click #btn" : "refreshTable"
},
render: function() {
this.$el.append( this.template() );
},
refreshTable: function() {
this.collection.reset();
console.log(this.collection.length)
this.collection.fetch();
},
buildRows: function(){
var mainview = this;
_(this.collection.models).each(function(model){
mainview.appendRow(model);
});
},
appendRow: function(model,i) {
var row = txnRow(model);
$('tbody',this.el).append(row.render().el);
}
so initially, i render this:
Row1
Row2
But with every click of the button that triggers refreshTable just appends 2 more rows to the table:
Row1
Row2
Row1
Row2
Row1
Row2
What am i missing?
It looks like you're emptying the collection, but not removing the old HTML. Maybe in render() try replacing the element's content rather than appending to it.
The backbone collection.reset() method has no effect on views. You will have to re render the view with the new data manually.
Your render function keeps appending elements. Backbone wont clear your $el before calling render, it leaves that upto you.
try changing your render function to somthing like this
render: function() {
this.$el.html( this.template() );
},
Related
Trying to make a reasonable teaching model of Backbone that shows proper ways to take advantage of backbone's features, with a grandparent, parent, and child views, models and collections...
I am trying to change a boolean attribute on a model, that can be instantiated across multiple parent views. How do I adjust the listers to accomplish this?
The current problem is that when you click on any non-last child view, it moves that child to the end AND re-instantiates it.
Plnkr
Click 'Add a representation'
Click 'Add a beat' (you can click this more than once)
Clicking any beat view other than the last one instantiates more views of the same beat
Child :
// our beat, which contains everything Backbone relating to the 'beat'
define("beat", ["jquery", "underscore", "backbone"], function($, _, Backbone) {
var beat = {};
//The model for our beat
beat.Model = Backbone.Model.extend({
defaults: {
selected: true
},
initialize: function(boolean){
if(boolean) {
this.selected = boolean;
}
}
});
//The collection of beats for our measure
beat.Collection = Backbone.Collection.extend({
model: beat.Model,
initialize: function(){
this.add([{selected: true}])
}
});
//A view for our representation
beat.View = Backbone.View.extend({
events: {
'click .beat' : 'toggleBeatModel'
},
initialize: function(options) {
if(options.model){
this.model=options.model;
this.container = options.container;
this.idAttr = options.idAttr;
}
this.model.on('change', this.render, this);
this.render();
},
render: function(){
// set the id on the empty div that currently exists
this.$el.attr('id', this.idAttr);
//This compiles the template
this.template = _.template($('#beat-template').html());
this.$el.html(this.template());
//This appends it to the DOM
$('#'+this.container).append(this.el);
return this;
},
toggleBeatModel: function() {
this.model.set('selected', !this.model.get('selected'));
this.trigger('beat:toggle');
}
});
return beat;
});
Parent :
// our representation, which contains everything Backbone relating to the 'representation'
define("representation", ["jquery", "underscore", "backbone", "beat"], function($, _, Backbone, Beat) {
var representation = {};
//The model for our representation
representation.Model = Backbone.Model.extend({
initialize: function(options) {
this.idAttr = options.idAttr;
this.type = options.type;
this.beatsCollection = options.beatsCollection;
//Not sure why we have to directly access the numOfBeats by .attributes, but w/e
}
});
//The collection for our representations
representation.Collection = Backbone.Collection.extend({
model: representation.Model,
initialize: function(){
}
});
//A view for our representation
representation.View = Backbone.View.extend({
events: {
'click .remove-representation' : 'removeRepresentation',
'click .toggle-representation' : 'toggleRepType',
'click .add-beat' : 'addBeat',
'click .remove-beat' : 'removeBeat'
},
initialize: function(options) {
if(options.model){this.model=options.model;}
// Dont use change per http://stackoverflow.com/questions/24811524/listen-to-a-collection-add-change-as-a-model-attribute-of-a-view#24811700
this.listenTo(this.model.beatsCollection, 'add remove reset', this.render);
this.listenTo(this.model, 'change', this.render);
},
render: function(){
// this.$el is a shortcut provided by Backbone to get the jQuery selector HTML object of this.el
// so this.$el === $(this.el)
// set the id on the empty div that currently exists
this.$el.attr('id', this.idAttr);
//This compiles the template
this.template = _.template($('#representation-template').html());
this.$el.html(this.template());
//This appends it to the DOM
$('#measure-rep-container').append(this.el);
_.each(this.model.beatsCollection.models, function(beat, index){
var beatView = new Beat.View({container:'beat-container-'+this.model.idAttr, model:beat, idAttr:this.model.idAttr+'-'+index });
}, this);
return this;
},
removeRepresentation: function() {
console.log("Removing " + this.idAttr);
this.model.destroy();
this.remove();
},
//remove: function() {
// this.$el.remove();
//},
toggleRepType: function() {
console.log('Toggling ' + this.idAttr + ' type from ' + this.model.get('type'));
this.model.set('type', (this.model.get('type') == 'line' ? 'circle' : 'line'));
console.log('Toggled ' + this.idAttr + ' type to ' + this.model.get('type'));
this.trigger('rep:toggle');
},
addBeat: function() {
this.trigger('rep:addbeat');
},
removeBeat: function() {
this.trigger('rep:removebeat');
}
});
return representation;
});
This answer should be working properly for all views, being able to create, or delete views without effecting non related views, and change attributes and have related views auto update. Again, this is to use as a teaching example to show how to properly set up a backbone app without the zombie views...
Problem
The reason you are seeing duplicate views created lies in the render() function for the Beat's view:
render: function(){
// set the id on the empty div that currently exists
this.$el.attr('id', this.idAttr);
//This compiles the template
this.template = _.template($('#beat-template').html());
this.$el.html(this.template());
//This appends it to the DOM
$('#'+this.container).append(this.el);
return this;
}
This function is called when:
when the model associated with the view changes
the beat view is first initialized
The first call is the one causing the problems. initialize() uses an event listener to watch for changes to the model to re-render it when necessary:
initialize: function(options) {
...
this.model.on('change', this.render, this); // case #1 above
this.render(); // case #2 above
...
},
Normally, this is fine, except that render() includes code to push the view into the DOM. That means that every time the model associated with the view changes state, the view not only re-renders, but is duplicated in the DOM.
This seems to cause a whole slew of problems in terms of event listeners being bound incorrectly. The reason, as far as I know, that this phenomenon isn't caused when there is just one beat present is because the representation itself also re-renders and removes the old zombie view. I don't entirely understand this behavior, but it definitely has something to do with the way the representation watches it's beatCollection.
Solution
The fix is quite simple: change where the view appends itself to the DOM. This line in render():
$('#'+this.container).append(this.el);
should be moved to initialize, like so:
initialize: function(options) {
if(options.model){
this.model=options.model;
this.container = options.container;
this.idAttr = options.idAttr;
}
this.model.on('change', this.render, this);
this.render();
$('#'+this.container).append(this.el); // add to the DOM after rendering/updating template
},
Plnkr demo with solution applied
I have a single page app built with Marionette that has a main view with a list of subviews.
The JSON which holds all application data is updated constantly. I've tried to separate region show code so that it will be run just once and not on every render.
Now the render event is fired on every timeout loop even though the JSON is static data and therefore change event should not call render. What is wrong? I assume it has something to do with .set but is there any other way to load the response from an array variable to the subview collection, since fetch will allow only url attribute and will not accept array variable?
This example is an extremely simplified version of the application code to concentrate on this specific problem.
Controller:
var Controller = {
showMainView: function(id){
// create model and fetch data on startup
var mainElement = new mainElement();
var mainElementFetched = mainElement.fetch({url: 'http://json.json'});
// fetch done, create view, show view in region, setTimeout
mainElementFetched.done(function(data){
var mainElementView = mainElementView({model:mainElement});
App.mainRegion.show(mainElementView);
setTimeout(updateJSON, 5000);
}
// timeOut loop to check for JSON changes
var updateJSON = function(){
mainElement.fetch({url: 'http://json.json'});
App.timeOut = setTimeout(updateJSON, 5000);
}
}
}
MainElement Model:
MainElement = Backbone.Model.extend({
parse : function(response){
// parsing code
return response;
}
});
MainElementView (Layout):
MainElementView = Backbone.Marionette.Layout.extend({
template: "#main-template",
initialize:function(){
//create collection for subelements
this.subElementCollection = new SubElementCollection();
//listen to change event, and fire callback only when change in model is detected
this.model.on('change', this.render, this);
},
regions:{
subsection : ".subsection"
},
onShow: function(){
// show subelements in subsection region when mainelementview is shown on screen, but not show on every render
this.subsection.show(new SubElementCompositeView({collection:this.subElementCollection}))
},
onRender : function(){
var response = this.model.response;
// get subelements when change event fires and parse the response
this.subElementCollection.set(response,{parse:true});
}
});
SubElement Model, Collection, ItemView, CompositeView:
SubElement = Backbone.Model.extend({});
SubElementCollection = Backbone.Collection.extend({
model:SubElement,
comparator : function(model){
var price = model.get('price');
return -(price);
},
parse:function(response){
// parsing code to get data to models from differents parts of JSON
return response;
}
});
SubElementItemView = Backbone.Marionette.ItemView.extend({
template: "#subelement-template",
tagName: "tr"
});
SubElementCompositeView = Backbone.Marionette.CompositeView.extend({
template: "#subelements-template",
tagName : "table",
itemView:SubElementItemView,
itemViewContainer : "tbody",
initialize: function(){
this.collection.on('change', this.render, this);
},
appendHtml : function(collectionView,itemView,index){
// SORTING CODE
},
onRender:function(collectionView,itemView,index){
// ADD IRRELEVANT EXTERNAL STUFF TO TEMPLATE AFTER RENDER
}
});
Check out the documentation. It says:
A "change" event will be triggered if the server's state differs from the current attributes.
In your MainElementView where you bind to your model's change event: this.model.on('change', this.render, this);, you are actually saying every time your model changes, call render.
If re-drawing the whole view is too slow, due to the amount of changes. Why don't you make your rendering more fine-grained? For example you could listen for specific change events and just change the DOM elements which need changing:
this.model.on('change:Name', function () {
this.$('[name=Name]').html(this.model.get('Name'));
}, this);
It is more work to set this up, but you could make it a bit cleverer by matching the model property names to your DOM element name or something.
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 $('#cartCount') in the .fetch callback injects the correction number of models. Unexpectedly, along with the correct .html() value the Chrome console.log return is (server side had zero models in the database to start with):
in error create PackagesView.js:88
0 PackagesView.js:89
in success fetch PackagesView.js:97
1
And I'm getting a 200 response from the create, so it should be "success" for both callbacks. I would have thought that the Backbone callback syntax for create and fetch were the same. Oh well, it seems to work.
Any feedback on this method is appreciated! Probably a better way to do this.
Incidentally this goes against the general advice here, although I do have a "very simple list" so perhaps its OK in the long run.
I have a Backbone view (see below) that I believe to be doing the right thing
Index = Backbone.View.extend({
render: function() {
var activities = new Activities();
activities.fetch();
var tpl = Handlebars.compile($("#activities-template").html());
$(this.el).html(tpl({activities: activities.toJSON()}));
return this;
}
});
If execute each line in the render() function with Chrome JS console I get the expected result with the element I pass in getting populated with the template output. However, when I run this using the following
var i = new Index({el: $("body")})
i.render()
"i.$el" is completely empty--the HTML is not getting rendered like it does in console. Any ideas why?
fetch is an AJAX call so there's no guarantee that activities.toJSON() will give you any data when you do this:
activities.fetch();
var tpl = Handlebars.compile($("#activities-template").html());
$(this.el).html(tpl({activities: activities.toJSON()}));
Executing the code in the console probably gives the AJAX call time to return with something before you try to use activities.
You should do two things:
Fix your template to do something sensible (such as show a loading... message of some sort) if activities is empty.
Attach your view's render to the collection's "reset" event:
initialize: function() {
// Or, more commonly, create the collection outside the view
// and say `new View({ collection: ... })`
this.collection = new Activities();
this.collection.on('reset', this.render, this);
this.collection.fetch();
},
render: function() {
var tpl = Handlebars.compile($("#activities-template").html());
this.$el.html(tpl({activities: this.collection.toJSON()}));
return this;
}
I also switched to this.$el, there's no need to $(this.el) when Backbone already gives you this.$el.
So I have a View that looks like this.
//base class
var SelectListView = Backbone.View.extend({
initialize: function() {
_.bindAll(this, 'addOne', 'addAll');
this.collection.bind('reset', this.addAll);
},
addAll: function() {
this.collection.each(this.addOne);
},
events: {
"change": "changedSelected"
},
changedSelected: function() {
this.selected = $(this.el);
this.setSelectedId($(this.el).val());
}
});
//my extended view
var PricingSelectListView = SelectListView.extend({
addOne: function(item) {
$(this.el).append(new PricingView({ model: item }).render().el);
}
});
I have instantiated the view like this...
var products = new ProductPricings();
var pricingsView = new PricingSelectListView({
el: $("#sel-product"),
collection: products
});
Somewhere else (another views custom method)I have updated the pricing view's collection
pricingsView.collection = new ProductPricings(filtered);
This does not seen to do anything.
pricingsView.render();
So now the collection has fewer items but the new view is never rendered or refreshed in the DOM.
How to I do I 1.) refresh the rendering in the DOM? 2.) Make it automatically refresh the DOM? Do I have to somehow tell it to render when ever the collection changes?
You bound addOne() to a reset event. When you just replace the pricingsView.collection instance then that event is not triggered and addOne() is not executed.
Try instead:
pricingsView.collection.reset(filtered);
This might work since you bind to collection's reset event already:
pricingsView.collection.reset(filtered);
http://backbonejs.org/#Collection-reset
You still have tweak your rendering logic to remove old markup from the view when reset happens.