After such a speedy response to my last question I thought I'd try my luck with another :o)
I'm using jQuery UI sortable to sort an ember view. Each item in the view is also a view (like a teaser).
I am adding sortable to the parent view on didInsertElement here.
<script type="text/x-handlebars">
App.SimpleRowListView = Em.View.extend({
didInsertElement: function() {
this.$().sortable({
handle: '.dragger',
items: '.simple-row',
axis: 'y',
update: function(event, ui) {
// update is probably the best event...
}
});
},
});
</script>
Whenever the list is updated I'd like to update my simpleRow.listPosition value to the current index of each .simple-row within it's parent element
I started adding an updateListPosition function to the view used for each row
<script>
updateListPosition : function() {
var index = $('#simple-row-wrapper .simple-row').index(this.$());
this.getPath('content').set('listPosition',index);
},
</script>
With the aim I'd connect my UI update event to trigger this on each of the child views.
I'm now wandering whether the update event should call a function on the controller to loop over all objects and set the listPosition. But in the controller I cannot access this.$() and so can't calculate the index
My plan was to use listPosition as a sorting property on the controller's array. But if there are better ways of sorting the controller array so that it reflects the changes made using .sortable()
Thanks again. I think this might be one quite a few people will want an answer for at some point :)
You need to go through the views. You can either loop each calling your updateListPosition function (which is kind of a heavy job) or you can do something like this
<script type="text/javascript">
App.SimpleRowListView = Em.View.extend({
didInsertElement: function() {
var self = this;
this.$().sortable({
handle: '.dragger',
items: '.simple-row',
axis: 'y',
update: function(event, ui) {
var rows = self.$('.simple-row').toArray();
rows.forEach(function(row) {
var view = Ember.View.views[$(row).attr('id')];
view.updateListPosition();
});
}
});
},
});
</script>
Or one version that seems a little lighter:
<script type="text/javascript">
App.SimpleRowListView = Em.View.extend({
didInsertElement: function() {
var self = this;
this.$().sortable({
handle: '.dragger',
items: '.simple-row',
axis: 'y',
update: function(event, ui) {
var rows = self.$('.simple-row').toArray();
rows.forEach(function(row, position) {
var view = Ember.View.views[$(row).attr('id')];
view. updateListPosition(position);
// pass the new position provided by forEach here and use it instead of calculating again
});
}
});
},
});
</script>
Related
I'm working with an API and Backbone.js at the moment.
I have two views, both render to the same document element #viewContainer. Both of these views render a table with a couple strings to decribe them and a button that opens a form in a modal.
View 1
App.Views.TaskList = Backbone.View.extend({
el: "#viewContainer",
tagName: 'tr',
events: {
"click button": "showTaskForm"
},
showTaskForm: function (event) {
event.preventDefault();
var id = $(event.currentTarget).data("id");
var item = this.collection.get(id);
var formView = new App.Views.Form({
model: item
});
formView.render();
},
render: function () {
changeActive($('#tasksLink'));
var template = _.template($("#taskList").html(), {});
$('#viewContainer').html(template);
// loop and render individual tasks.
this.collection.each(function (model) {
var variables = {
name: model.get('name'),
button: model.getButton()
};
var template = _.template($("#task").html(), variables);
$("#taskTable tbody").append(template);
});
},
collection: App.Collections.Tasks,
});
View 2
App.Views.ProcessList = Backbone.View.extend({
el: "#viewContainer",
tagName: 'tr',
events: {
"click button": "showStartForm"
},
showStartForm: function (event) {
event.preventDefault();
var id = $(event.currentTarget).data("id");
var item = this.collection.get(id);
var formView = new App.Views.Form({
model: item
});
formView.render();
},
collection: App.Collections.Processes,
render: function () {
changeActive($('#processLink'));
var template = _.template($("#processList").html(), {});
$('#viewContainer').html(template);
this.collection.each(function (model) {
var variables = {
processId: model.get('id'),
processName: model.get('name'),
button: model.getButton()
};
var template = _.template($('#process').html(), variables);
$('#processList tbody').append(template);
});
} });
Neither of these views are rendered by default, both need to be activated by a button on the page and they over-write each other in the DOM. However, which ever view is rendered first, the click event of the buttons in that view are the ones that are always fired.
If there is any more information needed from me let me know and I will edit the question.
Be sure to call undelegateEvents() in the first view when you render the second.
Since you're listening for events on the same elements, essentially you attached two listeners for click events on the same button, and when you change your views you are not cleaning up these listeners.
Here's an article that talks about managing events on view change, which should be really helpful to you.
http://lostechies.com/derickbailey/2011/09/15/zombies-run-managing-page-transitions-in-backbone-apps/
As other posters have pointed out, you need to watch out for 'zombie' views (i.e. making sure you undelegate events). If you're building even a moderately complex app, you'll want something that can scale. I find this pattern useful:
var BaseView = Backbone.View.extend({
render: function () {
this.$el.html(this.template());
return this;
},
close: function () {
if (this.onClose) this.onClose();
this.undelegateEvents();
this.$el.off();
this.$el.remove();
}
});
Then whenever you build a view you can do:
var view = BaseView.extend({
//your code
//now the .close() method is available whenever you need to close
//a view (no more zombies!).
});
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".
I'm using jQuery dataTables to display a table. I need to be able to pass a row selection event on to my Aura component that handles the selection and performs some operations on the data from that row.
In the initialize() function:
initialize: function()
{
$("#mytable tbody").click(function(event)
{
$(mytable.fnSettings().aoData).each(function ()
{
$(this.nTr).removeClass('row_selected');
});
$(event.target.parentNode).addClass('row_selected');
});
mytable = $('#mytable').dataTable();
},
I set up the click handler for the row selection, but how do I get a reference to the enclosing component so I can sandbox.emit() function to issue messages? I can put a reference to the component into the Closure, but that essentially makes this component a singleton and I could never have two instances of the component on the page at the same time.
Is there a standard way, using jQuery selectors or some other method, that I can retrieve a reference to the enclosing component from inside the click() handler?
Edit: I should never try to write code until I have had 32oz of caffine. You can pass a reference to the current component via the click() method itself. Like so:
$("#mytable tbody").click(this, function(event)
{
$(mytable.fnSettings().aoData).each(function ()
{
$(this.nTr).removeClass('row_selected');
});
$(event.target.parentNode).addClass('row_selected');
event.data.sandbox.emit('mychannel', {data: 'stuff'});
});
If I understand your question correctly, you could try something like this
initialize: function () {
var that = this;
$("#mytable tbody").click(function(event) {
//have acces to component as 'that'
});
}
what I used for events is view inside component configuration:
View: {
events: {
'click a[data-question-edit-id]': function (e) {
var button = $(e.currentTarget),
id = button.attr('data-question-edit-id'),
examId = this.component.examModel.get('id');
this.sandbox.router.navigate('/exams/' + examId + '/questions/' + id + '/edit', {trigger: true});
},
'click a[data-question-delete-id]': function (e) {
var button = $(e.currentTarget),
id = button.attr('data-question-delete-id');
this.component.showDeleteConfirmation(id);
}
}
}
If you'll find be helpful, here is my repo of aura project I'm working on:
https://github.com/lyubomyr-rudko/aura-test-project
I'm working on my first app using bbjs, after 10 tutorials and endless sources I am trying to come up with my code design.
I ask what is the best practice with views and templates. Also there is an events problem I am struggling with.
As I understand, the view is to be responsible for one element and its contents (and other sub-views).
For the code to be manageable, testable, etc.. the element/template is to be passed to the view on creation.
In my app Imho the view should hold the templates, because the visible element has many "states" and a different template for each state.
When the state changes, I guess its best to create a new view, but, is it possible for the view to update itself with new element?
App.Box = Backbone.Model.extend({
defaults: function() {
return {
media: "http://placehold.it/200x100",
text: "empty...",
type: "type1"
};
}
});
App.BoxView = Backbone.View.extend({
template: {},
templates: {
"type1": template('appboxtype1'),
"type2": template('appboxtype2')
},
events: {
'click .button': 'delete'
},
initialize: function(options) {
this.listenTo(this.model, 'change', this.render);
this.listenTo(this.model, 'destroy', this.remove);
this.render();
},
render: function() {
this.template = this.templates[ this.model.get("type") ];
// first method
this.$el.replaceWith( $($.parseHTML(this.template(this))) );
this.$el.attr("id", this.model.cid);
// second method
var $t_el = this.$el;
this.setElement( $($.parseHTML(this.template(this))) );
this.$el.attr("id", this.model.cid);
$t_el.replaceWith( this.$el );
this.delegateEvents();
//$('#'+this.model.cid).replaceWith( $(g.test.trim()) );
//! on the second render the events are no longer bind, deligateEvents doesn't help
return this;
},
// get values
text: function() { return this.model.get('text'); },
media: function() { return this.model.get('media'); },
delete: function() {
this.model.destroy();
}
});
Thanx! :)
Instead of trying to replace the view's root element ($el), just replace its content.
this.$el.html(this.template(this));
Events should still work then.
try this
render: function() {
html = '<div>your new html</div>';
var el = $(html);
this.$el.replaceWith(el);
this.setElement(el);
return this;
}
$.replaceWith will only replace the element in the DOM. But the this.$el still holds a reference to the now displaced old element. You need to call this.setElement(..) to update the this.$el field. Calling setElement will also undelegateEvents and delegateEvents events for you.
I came up with this solution: http://jsfiddle.net/Antonimo/vrQzF/4/
if anyone has a better idea its always welcome!
basically, in view:
var t_$el = this.$el;
this.$el = $($.parseHTML(this.template(this)));
this.$el.attr("id", this.cid);
if (t_$el.parent().length !== 0) { // if in dom
this.undelegateEvents();
t_$el.each(function(index, el){ // clean up
if( index !== 0 ){ $(el).remove(); }
});
t_$el.first().replaceWith(this.$el);
this.delegateEvents();
}
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);
}
});