My code gets the fileType and start new ImageView accordingly.
var frameIdRegion = new Marionette.Region({
el: '#viewerId'
});
// Create a new Backbone Marionette View with item model. Render View and Show it on Screen.
if(fileType === 'Image'){
frameIdRegion.close(imageView);
frameIdRegion.reset();
var imageView = new ImageView({model: item});
frameIdRegion.show(imageView);
$(".frameId img").show();
$(".frameId img").load(function(){
$("#fit_to_screen").trigger('click');
});
imageView.close();
}
else if(fileType === 'pdf'){
var objectView = new ObjectView({model: item});
frameIdRegion.reset();
frameIdRegion.show(objectView);
$("#pdf_viewer").show();
$('#pdf_viewer').trigger('focus');
}
else if(fileType === 'unsupported'){
var errorView = new ErrorView({model: item});
frameIdRegion.reset();
frameIdRegion.show(errorView);
}
But my Old instance of ImageView is not getting cleared when i start a new ImageView. And my events are occuring many times. This is my ImageView code.
var ImageView = Marionette.ItemView.extend({
template: template,
className: 'frameId',
onClose: function(){
this.remove();
this.unbind();
this.model.unbind("change", this.modelChanged);
}
});
Please help what i am doing wrong?
try using backbones listenTo function. It gets attached to whatever is calling it, so when your ItemView gets disposed then so will the event listener.
http://backbonejs.org/#Events-listenTo
It also has a stopListening method if you really need it. When your view is removed, it should automatically stop listening to everything that was called by listenTo
http://backbonejs.org/#View-remove
Related
I have a collection of items. I would like to keep track of the current selection. When the user clicks on a different item in the collection, I want to indicate that the item is selected and display the details of the selected item. Think of this as a list with a detail view (like a typical email client).
Example of a master-detail layout (source):
I currently have something like this (written in CoffeeScript, templates use haml-coffee):
class Collections.Items extends Backbone.Collection
model: Models.Item
setCurrentSelection: (id)->
# what to do here? Is this even the right way to do it?
getCurrentSelection: ->
# what to do here? Is this even the right way to do it?
class Views.ItemsPage extends Backbone.View
list_template: JST['items/list']
details_template: JST['items/details']
events:
'click .item': 'updateSelection'
initialize: (options)->
#collection = options.collection
render: ->
$('#items_list').html(#list_template(collection: #collection.toJSON())) # not sure if this is how to render a collection
$('#item_details').html(#details_template(item: #collection.currentSelection().toJSON())) # how to implement currentSelection?
#
updateSelection: (event)->
event.preventDefault()
item_id = $(event.currentTarget).data('id')
# mark the item as selected
# re-render using the new selection
# templates/items/list.hamlc
%ul
- for item in #collection
%li{data:{id: item.id}, class: ('selected' if item.selected?)} # TODO: How to check if selected?
= item.name
# templates/items/details.hamlc
%h2= #item.name
I'm not sure if I'm following you (my CoffeeScript is a bit rusty), but I think what you're trying to do is set a selected property on the appropriate model in your updateSelection method, and then re-render your view.
In other words:
updateSelection: (event)->
event.preventDefault()
item_id = $(event.currentTarget).data('id')
model = this.collection.get(item_id) # get the model to select
model.selected = true # mark the item as selected
this.render() # re-render using the new selection
even saying "my CoffeeScript is a bit rusty" is too much for me. But i'll still attempt to explain as best as i can in js.
First the backbone way is to keep models as a representation of a REST resource document. (server side - persisted data).
Client side presentation logic should stick to views. to remember which list item is visible in in the details part is job of the that specific view. initiating change request for details view model is job of the list of items.
the ideal way is to have two separate views for list and details. (you can also go a bit more ahead and have a view for every item in the list view.
parent view
var PageView = Backbone.View.extend({
initialize: function() {
//initialize child views
this.list = new ItemListView({
collection : this.collection //pass the collection to the list view
});
this.details = new ItemDetailView({
model : this.collection.at(1) //pass the first model for initial view
});
//handle selection change from list view and replace details view
this.list.on('itemSelect', function(selectedModel) {
this.details.remove();
this.details = new ItemDetailView({
model : selectedModel
});
this.renderDetails();
});
},
render: function() {
this.$el.html(this.template); // or this.$el.empty() if you have no template
this.renderList();
this.renderDetails();
},
renderList : function(){
this.$('#items_list').append(this.list.$el); //or any other jquery way to insert
this.list.render();
},
renderDetails : function(){
this.$('#item_details').append(this.details.$el); //or any other jquery way to insert
this.details.render();
}
});
list view
var ItemListView = Backbone.View.extend({
events : {
'click .item': 'updateSelection'
},
render: function() {
this.$el.html(this.template);
this.delegateEvents(); //this is important
}
updateSelection : function(){
var selectedModel;
// a mechanism to get the selected model here - can be same as yours with getting id from data attribute
// or you can have a child view setup for each model in the collection. which will trigger an event on click.
// such event will be first captured by the collection view and thn retriggerd for page view to listen.
this.trigger('itemSelect', selectedModel);
}
});
details view
var ItemDetailView = Backbone.View.extend({
render: function() {
this.$el.html(this.template);
this.delegateEvents(); //this is important
}
});
This won't persist the state through routes if you don't reuse your views. in that case you need to have a global state/event saving mechanism. somthing like following -
window.AppState = {};
_.extend(window.AppState, Backbone.Events);
//now your PageView initilize method becomes something like this -
initialize: function() {
//initialize child views
this.list = new ItemListView({
collection : this.collection //pass the collection to the list view
});
var firstModel;
if(window.AppState.SelectedModelId) {
firstModel = this.collection.get(window.AppState.SelectedModelId);
} else {
firstModel = this.collection.at(1);
}
this.details = new ItemDetailView({
model : firstModel //pass the first model for initial view
});
//handle selection change from list view and replace details view
this.list.on('itemSelect', function(selectedModel) {
window.AppState.SelectedModelId = selectedModel.id;
this.details.remove();
this.details = new ItemDetailView({
model : selectedModel
});
this.renderDetails();
});
}
EDIT
Handling selected class (highlight) in list view . see comments for reference.
list view template -
<ul>
<% _.each(collection, function(item, index){ %>
<li data-id='<%= item.id %>'><%= item.name %></li>
<% }); %>
</ul>
inside list view add following method -
changeSelectedHighlight : function(id){
this.$(li).removeClass('selected');
this.$("[data-id='" + id + "']").addClass('selected');
}
simply call this method from updateSelection method and during PageView initialize.
this.list.changeSelectedHighlight(firstModel.id);
In my Backbone app, I have the following
playlistView = new PlaylistView({ model: Playlist });
Playlist.getNewSongs(function() {
playlistView.initialize();
}, genre, numSongs);
Playlist.getNewSongs() is called back when some ajax request is finished. I want to re-initialize the view then. However, I believe the way I'm doing it leads to this problem of a view listening to a same event twice. Is calling initialize() like this acceptable? If not, what should I do instead?
Update:
I wrote this chrome extension in Backbone to learn Backbone, and it's in a design hell at the moment. I am in the middle of refactoring the entire codebase. The snippet below is my PlaylistView initialize() code block.
var PlaylistView = Backbone.View.extend({
el: '#expanded-container',
initialize: function() {
var playlistModel = this.model;
var bg = chrome.extension.getBackgroundPage();
if (!bg.player) {
console.log("aborting playlistView initialize because player isn't ready");
return;
}
this.listenTo(playlistModel.get('songs'), 'add', function (song) {
var songView = new SongView({ model: song });
this.$('.playlist-songs').prepend(songView.render().el);
});
this.$('#song-search-form-group').empty();
// Empty the current playlist and populate with newly loaded songs
this.$('.playlist-songs').empty();
var songs = playlistModel.get('songs').models;
// Add a search form
var userLocale = chrome.i18n.getMessage("##ui_locale");
var inputEl = '<input class="form-control flat" id="song-search-form" type="search" placeholder="John Lennon Imagine">' +
'<span class="search-heart-icon fa fa-heart"></span>'+
'<span class="search-input-icon fui-search"></span>';
}
this.$('#song-search-form-group').append(inputEl);
var form = this.$('input');
$(form).keypress(function (e) {
if (e.charCode == 13) {
var query = form.val();
playlistModel.lookUpAndAddSingleSong(query);
}
});
// Fetch song models from bg.Songs's localStorage
// Pass in reset option to prevent fetch() from calling "add" event
// for every Song stored in localStorage
if (playlistModel.get('musicChart').source == "myself") {
playlistModel.get('songs').fetch({ reset: true });
songs = playlistModel.get('songs').models;
}
// Create and render a song view for each song model in the collection
_.each(songs, function (song) {
var songView = new SongView({ model: song });
this.$('.playlist-songs').append(songView.render().el);
}, this);
// Highlight the currently played song
var currentSong = playlistModel.get('currentSong');
if (currentSong)
var currentVideoId = currentSong.get('videoId');
else {
var firstSong = playlistModel.get('songs').at(0);
if (!firstSong) {
// FIXME: this should be done via triggering event and by Popup model
$('.music-info').text(chrome.i18n.getMessage("try_different_chart"));
$('.music-info').fadeOut(2000);
//console.log("something wrong with the chart");
return;
}
var currentVideoId = firstSong.get('videoId');
}
_.find($('.list-group-item'), function (item) {
if (item.id == currentVideoId)
return $(item).addClass('active');
});
},
It is not wrong but probably not a good practice. You did not post the code in your initialize but maybe you have too much logic here.
If you are simply initializing the view again so that the new data is rendered, you should use event listener as such:
myView = Backbone. View.extend ({
initialize : function() {
// We bind the render method to the change event of the model.
//When the data of the model of the view changes, the method will be called.
this.model.bind( "change" , this.render, this);
// Other init code that you only need once goes here ...
this.template = _.template (templateLoader. get( 'config'));
},
// In the render method we update the view to represent the current model
render : function(eventName) {
$ (this.el ).html(this .template ((this.model .toJSON())));
return this;
}
});
If the logic in your initiialize is something totally else, please include it. Maybe there is a beter place for it.
here's the situation:
When page is opened for the first time, it already has prepared DOM by server(php).
If user has javascript turned on, then i want to convert my page to web app(or whatever you call it).
As soon as Javascript is initialized, Backbone fetches collection from server.
The problem is, that some of these fetched items are already on page.
Now how can i mark those items which already are in the DOM?
And how can i tie them up with the Backbone view?
Hooking up a Backbone.View to an existing DOM element is simple:
//get a referent to the view element
var $el = $("#foo");
//initialize new view
var view = new FooView({el:$el});
The view now handles the #foo element's events, and all the other View goodness. You shouldn't call view.render. If you do, it will re-render the view to the element. This means that you can't define any necessary code in the render method.
As to how to find out which elements are already in the DOM, and how to find the corresponding element for each view - that's a bit more complicated to answer without knowing exactly how your data and html looks like. As a general advice, consider using data-* attributes to match up the elements.
Let's say you have a DOM tree:
<ul id="list">
<li data-id="1">...</li>
<li data-id="2">...</li>
<li data-id="5">...</li>
</ul>
You could bind/render a model to the container like so:
var view;
//container element
var $list = $("ul#list");
//find item node by "data-id" attribute
var $item = $list.find("li[data-id='" + model.id+ "']");
if($item.length) {
//element was in the DOM, so bind to it
view = new View( {el:$item, model:model} );
} else {
//not in DOM, so create it
view = new View( {model:model} ).render();
$list.append(view.el);
}
Ok, i managed to do that like so:
var Collection = Backbone.Collection.extend({...});
var ItemView = Backbone.View.extend({...});
var ItemsView = Backbone.View.extend({
initialize: function () {
var that = this,
coll = new Collection;
coll.fetch({ success: function () {
that.collection = coll;
that.render();
}});
},
render: function () {
this.collection.each(this.addOne, this);
},
addOne: function (model) {
var selector = '#i'+model.get("id");
if( $(selector).length ) {
//If we are here, then element is already in the DOM
var itemView = new ItemView({ 'model': model, 'el': selector, 'existsInDom': true });
} else {
var itemView = new ItemView({ 'model':model });
}
}
});
I'm creating an ajax upload component which consists of a progress bar for each backbone view, this is how my view template looks like.
<script id="view-template-dropped-file" type="text/html">
<a><%=name %></a><span><%=fileSize%></span>
<div class="ui-progress-bar">
<div class="ui-progress"></div>
</div>
</script>
When I drop files on my drop area I create a view for each file like this
for (i = 0; i < files.length; i++) {
var view = new DroppedFileView({
model: new DroppedFile({
name: files[i].name,
fileSize: files[i].size
})
});
var $li = view.render().$el;
$('#droparea ul').append($li);
});
The drop area with some files added showing a progress bar for each file. http://cl.ly/Lf4v
Now when I press upload I need to show the progress for each file individually.
What I tried to do was to bind to an event in my DroppedFileView like this
initialize: function() {
var app = myapp.app;
app.bind('showProgress', this._progress, this);
}
and the _progress function
_progress: function(percentComplete) {
this.$el.find('.ui-progress').animateProgress((percentComplete * 100), function () { }, 2000);
}
and this is how I trigger the event from the drop area view
xhr: function () {
var xhr = new window.XMLHttpRequest();
xhr.upload.addEventListener("progress", function (e) {
if (e.lengthComputable) {
var percentComplete = e.loaded / e.total;
app.trigger('showProgress', percentComplete);
}
}, false);
return xhr;
}
of course this will not work because I listen to the same showProgress event in all views which will cause all progress bars to show the same progress.
So, is it possible to bind an event to a specified view so the progress can be updated individually or is events not a good approach?
You might want to consider making the DroppedFile model emit the progress events. So simply instead of triggering the event on app, trigger it on the model instance which is being uploaded.
Your sample code doesn't mention which class holds the xhr method, but it would make sense to define it on the model itself. In which case the event triggering is trivial:
xhr: function () {
var model = this;
var xhr = new window.XMLHttpRequest();
xhr.upload.addEventListener("progress", function (e) {
if (e.lengthComputable) {
var percentComplete = e.loaded / e.total;
model.trigger('showProgress', percentComplete);
}
}, false);
return xhr;
}
And in view constructor:
initialize: function() {
this.model.bind('showProgress', this._progress, this);
}
Edit based on comments:
Even if your view structure is a bit more complicated than I assumed above, in my opinion using the DroppedFile model as event emitter is the way to go. If one DroppedFileView represents DroppedFile, it should reflect the state of the model it makes sense.
Just keep track of the models in DropzoneView, just like (or instead of how) you do now with the files in the DropzoneView.files. Whether you want to have the actual AJAX request to be the responsibility of the view or refactor it to the individual models doesn't really matter.
I render a collection of models, which is associated with a collectionView where when rendered each element in the collection has its own 'itemview' which is rendered.
When a collection is sorted and the listView re-rendered based on the new order, I had been creating a totally new view for each item, and as I was not clearing up any previous instances of views associated with that model, I believe zombies being left around.
So initially rendering my collection I would do...
render : function() {
$(this.el).empty();
var content = this.template.tmpl({});
$(this.el).html(content);
sortingView.el ='#sorting-container';
var els = [];
_.each(this.collection.models, function(model){
var view = new TB_BB.RequestItemView({model : model});
els.push(view.render().el);
});
$('#request-list').append(els);
sortingView.render();
return this;
}
So whenever the render function was called a second/third etc time, I had not cleared up the TB_BB.RequestItemView (hence the zombies)
To overcome this I tried to add some simple caching in the collections view, so that instead of creating a new itemview if it had already been created use that instead. My code
initialize : function(){
_.bindAll(this,"render");
this.collection.bind("add", this.render);
this.collection.bind("remove", this.render);
this.template = $("#request-list-template");
this.views = {};
},
events : {
"change #sort" : "changesort",
"click #add-offer" : "addoffer",
"click #alert-button" : "addalert"
},
render : function() {
$(this.el).empty();
outerthis = this;
var content = this.template.tmpl({});
$(this.el).html(content);
sortingView.el ='#sorting-container';
var els = [];
_.each(this.collection.models, function(model){
var view;
if(outerthis.views[model.get('id')]) {
view = outerthis.views[model.get('id')];
} else {
view = new TB_BB.RequestItemView({model : model});
outerthis.views[model.get('id')] = view;
}
});
$('#request-list').append(els);
sortingView.render();
return this;
}
So this works in so much as the views are re-used - however what I have noticed is that if I use a cached view (e.g. the collection has been sorted and the render function finds a cached view) that all of the events on the sub itemview stop working? why is that?
Also could anyone suggest a better way of doing this?
You can use delegateEvents ( http://documentcloud.github.com/backbone/#View-delegateEvents ) to bind the events again.
As OlliM mentioned the reason is because the events are bound to the dom element, but instead of rebinding the element you can also just detach them instead of removing them (detach keeps the event bindings http://api.jquery.com/detach/)
something like
var $sortContainer = $('#sorting-container');
$('li', $sortContainer).detach();
And then just reattach the element
$cnt.append(view.el);
I would also consider using a document fragment while rebuilding/sorting the list and then attaching appending that instead.