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Select2 Event for creating a new tag

I'm using the jQuery Select2 (v4) plugin for a tag selector.
I want to listen for when a new tag is created in the select element and fire an ajax request to store the new tag. I discovered there is the createTag event but this seems to fire every time a letter is entered into the select2 element. As shown in my fiddle: http://jsfiddle.net/3qkgagwk/1/
Is there a similar event that only fires when the new tag has finished being entered? I.e. it's enclosed by a grey box enclosing it.

I can't find any native method unfortunately. But if you're interested in simple "workarounds", maybe this get you closer:
$('.select2').select2({
tags: true,
tokenSeparators: [",", " "],
createTag: function (tag) {
return {
id: tag.term,
text: tag.term,
// add indicator:
isNew : true
};
}
}).on("select2:select", function(e) {
if(e.params.data.isNew){
// append the new option element prenamently:
$(this).find('[value="'+e.params.data.id+'"]').replaceWith('<option selected value="'+e.params.data.id+'">'+e.params.data.text+'</option>');
// store the new tag:
$.ajax({
// ...
});
}
});
DEMO
[EDIT]
(Small update: see #Alex comment below)
The above will work only if the tag is added with mouse. For tags added by hitting space or comma, use change event.
Then you can filter option with data-select2-tag="true" attribute (new added tag):
$('.select2').select2({
tags: true,
tokenSeparators: [",", " "]
}).on("change", function(e) {
var isNew = $(this).find('[data-select2-tag="true"]');
if(isNew.length && $.inArray(isNew.val(), $(this).val()) !== -1){
isNew.replaceWith('<option selected value="'+isNew.val()+'">'+isNew.val()+'</option>');
$.ajax({
// ... store tag ...
});
}
});
DEMO 2

The only event listener that worked for me when creating a new tag was:
.on("select2:close", function() {
(my code)
})
This was triggered for new tags and selecting from the list. change, select2:select, select2:selecting and any others did not work.

One more simple check will be this based on the difference in the args of the event .....
While I was dealing with this situation, I had seen this difference; that when the new element is created the event args data does not have an element object but it exists when selecting an already available option...
.on('select2:selecting', function (e) {
if (typeof e.params.args.data.element == 'undefined') {
// do a further check if the item created id is not empty..
if( e.params.args.data.id != "" ){
// code to be executed after new tag creation
}
}
})

Another workaround. Just insert it to the beginning:
}).on('select2:selecting', function (evt) {
var stringOriginal = (function (value) {
// creation of new tag
if (!_.isString(value)) {
return value.html();
}
// picking existing
return value;
})(evt.params.args.data.text);
........
It relies on underscore.js for checking if it's string or not. You can replace _.isString method with whatever you like.
It uses the fact that when new term is created it's always an object.

Meteor: instantiate a Session without the click event

Using Meteor 0.9+.
Is there a way to instantiate a session as soon as the page renders?
I have a dynamic list of names that display upon clicking a .li element using the click event. This is fine. But I would like the user now to see at least one list, i.e. as if they have already clicked one of the .li elements when they land on the page.
Template.nameList.events({
'click li.title': function(e) {
e.preventDefault();
Session.set('postId', this._id);
var selectedId = Session.get('postId');
}
});

You could use template.created or template.rendered callback:
Template.nameList.rendered = function() {
Session.set('postId', this.data.someId);
};
You could also use IR onBeforeAction callback:
NameListRouter = RouteController.extend({
onBeforeAction: function() {
Session.set('postId', this.params.someId);
};
});

Meteor JS: What is the best way to store states for a specific template instance?

I'm learning about Session and reactive data sources in Meteor JS. They work great for setting global UI states. However, I can't figure out how to scope them to a specific instance of a template.
Here's what I'm trying to do
I have multiple contenteditable elements on a page. Below each is an "Edit" button. When the user clicks on the Edit button, it should focus on the element and also show "Save" and "Cancel" buttons.
If the user clicks "Cancel", then any changes are eliminated, and the template instance should rerender with the original content.
Here's the code I have so far
// Helper
Template.form.helpers({
editState: function() {
return Session.get("editState");
}
});
// Rendered
Template.form.rendered = function(e){
var $this = $(this.firstNode);
var formField = this.find('.form-field');
if (Session.get("editState")) formField.focus();
};
// Event map
Template.form.events({
'click .edit-btn' : function (e, template) {
e.preventDefault();
Session.set("editState", "is-editing");
},
'click .cancel-btn' : function (e, template) {
e.preventDefault();
Session.set("editState", null);
},
});
// Template
<template name="form">
<div class="{{editState}}">
<p class="form-field" contenteditable>
{{descriptionText}}
</p>
</div>
Edit
Save
Cancel
</template>
// CSS
.edit-btn
.cancel-btn,
.save-btn {
display: inline-block;
}
.cancel-btn,
.save-btn {
display: none;
}
.is-editing .cancel-btn,
.is-editing .save-btn {
display: inline-block;
}
The problem
If I have more than one instance of the Form template, then .form-field gets focused for each one, instead of just the one being edited. How do I make so that only the one being edited gets focused?

You can render a template with data, which is basically just an object passed to it when inserted in to a page.
The data could simply be the key to use in the Session for editState.
eg, render the template with Template.form({editStateKey:'editState-topForm'})
you could make a handlebars helper eg,
Handlebars.registerHelper('formWithOptions',
function(editStateKey){
return Template.form({editStateKey:editStateKey})
});
then insert it in your template with
{{{formWithOptions 'editState-topForm'}}} (note the triple {, })
Next, change references from Session.x('editState') to Session.x(this.editStateKey)/ Session.x(this.data.editStateKey)
Template.form.helpers({
editState: function() {
return Session.get(this.editStateKey);
}
});
// Rendered
Template.form.rendered = function(e){
var $this = $(this.firstNode);
var formField = this.find('.form-field');
if (Session.get(this.data.editStateKey)) formField.focus();
};
// Event map
Template.form.events({
'click .edit-btn' : function (e, template) {
e.preventDefault();
Session.set(this.editStateKey, "is-editing");
},
'click .cancel-btn' : function (e, template) {
e.preventDefault();
Session.set(this.editStateKey, null);
},
});
Note: if you are using iron-router it has additional api's for passing data to templates.
Note2: In meteor 1.0 there is supposed to be better support for writing your own widgets. Which should allow better control over this sort of thing.

As a matter of policy I avoid Session in almost all cases. I feel their global scope leads to bad habits and lack of good discipline regarding separation-of-concerns as your application grows. Also because of their global scope, Session can lead to trouble when rendering multiple instances of a template. For those reasons I feel other approaches are more scalable.
Alternative approaches
1 addClass/removeClass
Instead of setting a state then reacting to it elsewhere, can you perform the needed action directly. Here classes display and hide blocks as needed:
'click .js-edit-action': function(event, t) {
var $this = $(event.currentTarget),
container = $this.parents('.phenom-comment');
// open and focus
container.addClass('editing');
container.find('textarea').focus();
},
'click .js-confirm-delete-action': function(event, t) {
CardComments.remove(this._id);
},
2 ReactiveVar scoped to template instance
if (Meteor.isClient) {
Template.hello.created = function () {
// counter starts at 0
this.counter = new ReactiveVar(0);
};
Template.hello.helpers({
counter: function () {
return Template.instance().counter.get();
}
});
Template.hello.events({
'click button': function (event, template) {
// increment the counter when button is clicked
template.counter.set(template.counter.get() + 1);
}
});
}
http://meteorcapture.com/a-look-at-local-template-state/
3 Iron-Router's state variables
Get
Router.route('/posts/:_id', {name: 'post'});
PostController = RouteController.extend({
action: function () {
// set the reactive state variable "postId" with a value
// of the id from our url
this.state.set('postId', this.params._id);
this.render();
}
});
Set
Template.Post.helpers({
postId: function () {
var controller = Iron.controller();
// reactively return the value of postId
return controller.state.get('postId');
}
});
https://github.com/iron-meteor/iron-router/blob/devel/Guide.md#setting-reactive-state-variables
4 Collection data
Another approach is to simply state by updating data in your collection. Sometimes this makes perfect sense.
5 update the data context
Session is often the worse choice in my opinion. Also I don't personally use #3 as I feel like being less tied to iron-router is better incase we ever want to switch to another router package such as "Flow".

How does this click handler get assigned to a DOM element?

Now that I understand Backbone a little better (I Hope) I've been going through this App with a fine tooth comb to understand how it works:
https://github.com/ccoenraets/nodecellar/tree/master/public
The latest thing that's stumped me is the EL tag in windetails.js (here: https://github.com/ccoenraets/nodecellar/blob/master/public/js/views/winedetails.js)
I'll paste the relevant code below, but my question is how does this view's EL property get assigned? As you'll notice in the view definition no EL tag is defined, nor is there an idTag or className property assigned. However I verified in firebug that this view is indeed listening on a DIV tag in the middle of the DOM (just underneath the content DIV actually). So how did it get attached there? If not for that the Click handler would not work properly but it does. All of the previous views which look like there were created in the same way have unattached EL properties.
window.WineView = Backbone.View.extend({
initialize: function () {
this.render();
},
render: function () {
$(this.el).html(this.template(this.model.toJSON()));
return this;
},
events: {
"change" : "change",
"click .save" : "beforeSave",
"click .delete" : "deleteWine",
"drop #picture" : "dropHandler"
},
change: function (event) {
// Remove any existing alert message
utils.hideAlert();
// Apply the change to the model
var target = event.target;
var change = {};
change[target.name] = target.value;
this.model.set(change);
// Run validation rule (if any) on changed item
var check = this.model.validateItem(target.id);
if (check.isValid === false) {
utils.addValidationError(target.id, check.message);
} else {
utils.removeValidationError(target.id);
}
},
beforeSave: function () {
var self = this;
var check = this.model.validateAll();
if (check.isValid === false) {
utils.displayValidationErrors(check.messages);
return false;
}
this.saveWine();
return false;
},
saveWine: function () {
var self = this;
console.log('before save');
this.model.save(null, {
success: function (model) {
self.render();
app.navigate('wines/' + model.id, false);
utils.showAlert('Success!', 'Wine saved successfully', 'alert-success');
},
error: function () {
utils.showAlert('Error', 'An error occurred while trying to delete this item', 'alert-error');
}
});
},
deleteWine: function () {
this.model.destroy({
success: function () {
alert('Wine deleted successfully');
window.history.back();
}
});
return false;
},
dropHandler: function (event) {
event.stopPropagation();
event.preventDefault();
var e = event.originalEvent;
e.dataTransfer.dropEffect = 'copy';
this.pictureFile = e.dataTransfer.files[0];
// Read the image file from the local file system and display it in the img tag
var reader = new FileReader();
reader.onloadend = function () {
$('#picture').attr('src', reader.result);
};
reader.readAsDataURL(this.pictureFile);
}
});
EDIT
There's been a lot of talk about this pattern:
$(x).append(v.render().el)
Someone correct me if I'm wrong but as I understand it this is a Jquery call to update the DOM at the "x" tag with the contents of the "el" property from the v object (after render is called). This technique should render content into the DOM EVEN IF the "el" property has not previously been set and is an "unattached div" provided it has had valid content previously written to it from the render method.
However after the content has been written to the DOM the "el" property still remains an unattached div until it is directly assigned to the DOM.
I verified through Firebug that this Backbone app has two views which are rendered this exact way and both have unattached div el properties. Those are the wineList view and the homeView. However, the 3rd view is the WineDetail view and it does not seem to have an unattached EL property. It's EL property seems to be attached and furthermore is facilitating a click event. My question is how did this EL property get attached and assigned to the DOM?

The answer can be found by looking at the internals of Backbone.View.
Looking at the constructor:
var View = Backbone.View = function(options) {
this.cid = _.uniqueId('view');
this._configure(options || {});
//this function is responsible for the creation of the `this.el` property.
this._ensureElement();
this.initialize.apply(this, arguments);
this.delegateEvents();
};
Ensure that the View has a DOM element to render into. If this.el is a
string, pass it through $(), take the first matching element, and
re-assign it to el. Otherwise, create an element from the id,
className and tagName properties. http://backbonejs.org/docs/backbone.html#section-133
Now that we know where this.el comes from, have a look at the events docs to see how it's handled.
The view is instantiated in main.js
$('#content').html(new WineView({model: wine}).el);
EDIT:
None of which explains how the View Object's EL property is set and
and how the click trigger works.
I will try to explain it better:
this.el is created by a call to this._ensureElement in the Backbone.View constructor. We can also see that this.render is called from the initialize function which runs at instanciation time. We can see that in this.render, we set the content of this.el to the result of applying this.template to the model.
Now, during the initialization process of a Backbone.View, right after this.initialize is called, the events config is processed by making a call to this.delegateEvents. This is where event listeners will get attached using the given selectors. Note that most events will get attached directly to this.el and make use of event delegation, instead of attaching the events directly on the children elements.
At this point, we are left with a this.el that contains all the necessary markup and has all the event listeners setup. However, this.el is still not part of the DOM yet.
But from the code, we can see that this.el will be attached to the DOM as a children of the #content element after the instanciation of the view:
$('#content').html(new WineView({model: wine}).el);

The last three lines in this piece of code:
events: {
"change" : "change",
"click .save" : "beforeSave",
"click .delete" : "deleteWine",
"drop #picture" : "dropHandler"
},
look like this pattern (looking at the 2nd line in the events structure):
"click" = event to register a handler for
".save" = selector to use for selecting objects for the event handler
beforeSave = method to call when the event fires

Backbone.js : repopulate or recreate the view?

In my web application, I have a user list in a table on the left, and a user detail pane on the right. When the admin clicks a user in the table, its details should be displayed on the right.
I have a UserListView and UserRowView on the left, and a UserDetailView on the right. Things kind of work, but I have a weird behavior. If I click some users on the left, then click delete on one of them, I get successive javascript confirm boxes for all users that have been displayed.
It looks like event bindings of all previously displayed views have not been removed, which seems to be normal. I should not do a new UserDetailView every time on UserRowView? Should I maintain a view and change its reference model? Should I keep track of the current view and remove it before creating a new one? I'm kind of lost and any idea will be welcome. Thank you !
Here is the code of the left view (row display, click event, right view creation)
window.UserRowView = Backbone.View.extend({
tagName : "tr",
events : {
"click" : "click",
},
render : function() {
$(this.el).html(ich.bbViewUserTr(this.model.toJSON()));
return this;
},
click : function() {
var view = new UserDetailView({model:this.model})
view.render()
}
})
And the code for right view (delete button)
window.UserDetailView = Backbone.View.extend({
el : $("#bbBoxUserDetail"),
events : {
"click .delete" : "deleteUser"
},
initialize : function() {
this.model.bind('destroy', function(){this.el.hide()}, this);
},
render : function() {
this.el.html(ich.bbViewUserDetail(this.model.toJSON()));
this.el.show();
},
deleteUser : function() {
if (confirm("Really delete user " + this.model.get("login") + "?"))
this.model.destroy();
return false;
}
})

I always destroy and create views because as my single page app gets bigger and bigger, keeping unused live views in memory just so that I can re-use them would become difficult to maintain.
Here's a simplified version of a technique that I use to clean-up my Views to avoid memory leaks.
I first create a BaseView that all of my views inherit from. The basic idea is that my View will keep a reference to all of the events to which it's subscribed to, so that when it's time to dispose the View, all of those bindings will automatically be unbound. Here's an example implementation of my BaseView:
var BaseView = function (options) {
this.bindings = [];
Backbone.View.apply(this, [options]);
};
_.extend(BaseView.prototype, Backbone.View.prototype, {
bindTo: function (model, ev, callback) {
model.bind(ev, callback, this);
this.bindings.push({ model: model, ev: ev, callback: callback });
},
unbindFromAll: function () {
_.each(this.bindings, function (binding) {
binding.model.unbind(binding.ev, binding.callback);
});
this.bindings = [];
},
dispose: function () {
this.unbindFromAll(); // Will unbind all events this view has bound to
this.unbind(); // This will unbind all listeners to events from
// this view. This is probably not necessary
// because this view will be garbage collected.
this.remove(); // Uses the default Backbone.View.remove() method which
// removes this.el from the DOM and removes DOM events.
}
});
BaseView.extend = Backbone.View.extend;
Whenever a View needs to bind to an event on a model or collection, I would use the bindTo method. For example:
var SampleView = BaseView.extend({
initialize: function(){
this.bindTo(this.model, 'change', this.render);
this.bindTo(this.collection, 'reset', this.doSomething);
}
});
Whenever I remove a view, I just call the dispose method which will clean everything up automatically:
var sampleView = new SampleView({model: some_model, collection: some_collection});
sampleView.dispose();
I shared this technique with the folks who are writing the "Backbone.js on Rails" ebook and I believe this is the technique that they've adopted for the book.
Update: 2014-03-24
As of Backone 0.9.9, listenTo and stopListening were added to Events using the same bindTo and unbindFromAll techniques shown above. Also, View.remove calls stopListening automatically, so binding and unbinding is as easy as this now:
var SampleView = BaseView.extend({
initialize: function(){
this.listenTo(this.model, 'change', this.render);
}
});
var sampleView = new SampleView({model: some_model});
sampleView.remove();

I blogged about this recently, and showed several things that I do in my apps to handle these scenarios:
http://lostechies.com/derickbailey/2011/09/15/zombies-run-managing-page-transitions-in-backbone-apps/

This is a common condition. If you create a new view every time, all old views will still be bound to all of the events. One thing you can do is create a function on your view called detatch:
detatch: function() {
$(this.el).unbind();
this.model.unbind();
Then, before you create the new view, make sure to call detatch on the old view.
Of course, as you mentioned, you can always create one "detail" view and never change it. You can bind to the "change" event on the model (from the view) to re-render yourself. Add this to your initializer:
this.model.bind('change', this.render)
Doing that will cause the details pane to re-render EVERY time a change is made to the model. You can get finer granularity by watching for a single property: "change:propName".
Of course, doing this requires a common model that the item View has reference to as well as the higher level list view and the details view.
Hope this helps!

To fix events binding multiple times,
$("#my_app_container").unbind()
//Instantiate your views here
Using the above line before instantiating the new Views from route, solved the issue I had with zombie views.

I think most people start with Backbone will create the view as in your code:
var view = new UserDetailView({model:this.model});
This code creates zombie view, because we might constantly create new view without cleanup existing view. However it's not convenient to call view.dispose() for all Backbone Views in your app (especially if we create views in for loop)
I think the best timing to put cleanup code is before creating new view. My solution is to create a helper to do this cleanup:
window.VM = window.VM || {};
VM.views = VM.views || {};
VM.createView = function(name, callback) {
if (typeof VM.views[name] !== 'undefined') {
// Cleanup view
// Remove all of the view's delegated events
VM.views[name].undelegateEvents();
// Remove view from the DOM
VM.views[name].remove();
// Removes all callbacks on view
VM.views[name].off();
if (typeof VM.views[name].close === 'function') {
VM.views[name].close();
}
}
VM.views[name] = callback();
return VM.views[name];
}
VM.reuseView = function(name, callback) {
if (typeof VM.views[name] !== 'undefined') {
return VM.views[name];
}
VM.views[name] = callback();
return VM.views[name];
}
Using VM to create your view will help cleanup any existing view without having to call view.dispose(). You can do a small modification to your code from
var view = new UserDetailView({model:this.model});
to
var view = VM.createView("unique_view_name", function() {
return new UserDetailView({model:this.model});
});
So it is up to you if you want to reuse view instead of constantly creating it, as long as the view is clean, you don't need to worry. Just change createView to reuseView:
var view = VM.reuseView("unique_view_name", function() {
return new UserDetailView({model:this.model});
});
Detailed code and attribution is posted at https://github.com/thomasdao/Backbone-View-Manager

One alternative is to bind, as opposed to creating a series of new views and then unbinding those views. You'd accomplish this doing something like:
window.User = Backbone.Model.extend({
});
window.MyViewModel = Backbone.Model.extend({
});
window.myView = Backbone.View.extend({
initialize: function(){
this.model.on('change', this.alert, this);
},
alert: function(){
alert("changed");
}
});
You'd set the model of myView to myViewModel, which would be set to a User model. This way, if you set myViewModel to another user (i.e., changing its attributes) then it could trigger a render function in the view with the new attributes.
One problem is that this breaks the link to the original model. You could get around this by either using a collection object, or by setting the user model as an attribute of the viewmodel. Then, this would be accessible in the view as myview.model.get("model").

Use this method for clearing the child views and current views from memory.
//FIRST EXTEND THE BACKBONE VIEW....
//Extending the backbone view...
Backbone.View.prototype.destroy_view = function()
{
//for doing something before closing.....
if (this.beforeClose) {
this.beforeClose();
}
//For destroying the related child views...
if (this.destroyChild)
{
this.destroyChild();
}
this.undelegateEvents();
$(this.el).removeData().unbind();
//Remove view from DOM
this.remove();
Backbone.View.prototype.remove.call(this);
}
//Function for destroying the child views...
Backbone.View.prototype.destroyChild = function(){
console.info("Closing the child views...");
//Remember to push the child views of a parent view using this.childViews
if(this.childViews){
var len = this.childViews.length;
for(var i=0; i<len; i++){
this.childViews[i].destroy_view();
}
}//End of if statement
} //End of destroyChild function
//Now extending the Router ..
var Test_Routers = Backbone.Router.extend({
//Always call this function before calling a route call function...
closePreviousViews: function() {
console.log("Closing the pervious in memory views...");
if (this.currentView)
this.currentView.destroy_view();
},
routes:{
"test" : "testRoute"
},
testRoute: function(){
//Always call this method before calling the route..
this.closePreviousViews();
.....
}
//Now calling the views...
$(document).ready(function(e) {
var Router = new Test_Routers();
Backbone.history.start({root: "/"});
});
//Now showing how to push child views in parent views and setting of current views...
var Test_View = Backbone.View.extend({
initialize:function(){
//Now setting the current view..
Router.currentView = this;
//If your views contains child views then first initialize...
this.childViews = [];
//Now push any child views you create in this parent view.
//It will automatically get deleted
//this.childViews.push(childView);
}
});