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Backbone - Access a View's $el.attr outside of the ItemView

I have the following ItemView (there is no model associated with the view, it's a very basic "form" which has a submit or cancel and a single input field):
App.BasicForm = Backbone.Marionette.ItemView.extend({
template: "build/templates/basic-form.html",
tagName: "div",
attributes: {
id: "some-id",
style: "display: none;"
},
events: {
"click button#bf-submit": "bfSubmit",
"click button#bf-close": "bfClose"
},
bfSubmit: function() {
var bfInputField= document.getElementById('bfSomeData').value;
},
bfClose: function() {
this.$el.hide();
}
});
So by default, this view is hidden (but is instantiated when App starts).
I want to have a button which, when clicked, simply changes the attribute style display to block.
I can do this easily like this:
document.getElementById('bfBasicFormDiv').style.display = "block";
However, I'd rather call the view's $el.attr and edit it there, something along the lines of:
App.BasicForm.$el.attr({style: "display: block;"});
However, this returns an undefined, and I can see no way of retrieving the attribute of the View (it's easy with models using .get()) but that doesn't hold for a view.
Thank you for any advice.
Gary

App.BasicForm is not an instance, so it doesn't hold an element. You need to initialize it and you will be able to reference the element with $el:
var basicForm = new App.BasicForm({
el: document.getElementById('bfBasicFormDiv')
});
basicForm.$el.css({display: "block"});

Backbone and jQuery slider

So I've been struggling for quire sometime to do this. I am building a dynamic form generator tool. One of the functions is that the user should be able to use a jQuery slider to select the font size. I use Underscore templates to create divs for the slider. So everytime a user selects a Label input, this underscore template is loaded and I call the slider() fn to initialize it. Here's is the part of the code that does this
UnderscoreTemplate
<!-- template for plain text inpt to be shown in form generate -->
<script type="text/template" id="text-generate-template">
<div class="row">
<div class="col-sm-10">
<input type="text" placeholder="Enter text here" class="label-name form-control" value="<%=model.get('label')%>">
</div>
<button type="button" class="close" id="remove-element" >×</button>
</div>
<div class="row col-sm-6" style="margin-top:10px">
<div id="slider-<%=model.cid%>"></div>
<small>Font Size: <%=model.get('fontSize')%>px </small>
</div>
</script>
So as per the code ablove, each dynamically loaded element has a unique slider with a unique ID.
The Backbone Model extends from a Base element called "Element"
var TextElement = Element.extend({
defaults:function(){
return _.extend({}, Element.prototype.defaults,{
name: 'PlainText',
generateTemplateType: 'text-generate-template',
previewTemplateType:'text-template',
textAlign: 'center'
});
}
});
The view which is responsible for generating the html is
var ElementView = Backbone.View.extend({
tagName: 'li',
events : {
},
initialize : function(){
this.listenTo(this.model,'change', this.render);
this.render();
},
render : function(){
var htmlContent = $('#'+this.model.get('generateTemplateType')).html();
var content = _.template( htmlContent, {elementType : elementTypes, model : this.model} );
this.$el.html( content );
me = this;
if(this.model.get('name') == 'PlainText'){
this.$el.find('#slider-'+this.model.cid).slider({
min: 10,
max:40,
step: 1,
value:me.model.get('fontSize') > 9 ? me.model.get('fontSize') : 24,
change: function(event, ui) {
me.slide(event, ui.value);
}
});
}
return this;
},
slide: function(event, index){
console.log("the models id in slide function -> "+this.model.cid);
this.model.set('fontSize', index);
}
});
So what I do here is that every time I detect a change, I update this model's fontSize to the new value passed in through the Slider.
THe collection to which this model belongs to recognises this changes and rerenders itself.
When there is only one such element on the page, then everything works fine. The moment the user adds more than one element and tried to change the font size for each item, then only the font size of the last element is changed. Regardless of whether I slide the first , second or the third element it always sets the change to the last model in the collection and the last model get rerendered with the incorrect font size value.
I tried console logging the id of the model in the slide function and it always seems to return the last models ID regardless of which slider I use.
What am I doing wrong here??

You have an accidental global variable right here:
me = this;
A side effect of this is that every instance of ElementView will end up sharing exactly the same me and that me will be the last ElementView you instantiate. Sound familiar?
The solution is to use a local variable:
var me = this;
or, if you don't need the slider's this inside the callback, use a bound function instead:
value: this.model.get('fontSize') > 9 ? this.model.get('fontSize') : 24,
change: _(function(event, ui) {
this.slide(event, ui.value);
}).bind(this)
You could also use $.proxy or Function.prototype.bind if you prefer those over _.bind.

Titanium Alloy ListView Nested Model Array of Tags

I am using Titanium Alloy version 3.2. I have a collection of posts in a listview. My data looks like this:
[
{ username: 'dude', imageUrl: 'url', tags: ['tag1','tag2','tag3'] },
{ username: 'wheres', imageUrl: 'url', tags: ['tag1'] },
{ username: 'my', imageUrl: 'url', tags: ['tag1','tag2','tag3','tag4'] },
{ username: 'car', imageUrl: 'url', tags: ['tag1','tag2'] }
]
And here is the xml. This works only for username and image. I can't figure out how to add the tags to each post.
<ListView id="streamListview">
<Templates>
<ItemTemplate name="template" id="template">
<View class="item-container">
<ImageView bindId="pic" class="pic"/>
<Label bindId="username" class="username"/>
</View>
</ItemTemplate>
</Templates>
<ListSection id="section">
<ListItem template="template" class="list-item"/>
</ListSection>
</ListView>
And my controller code (without the tags)
var posts = [];
for (var i=0; i<data.length; i++){
var post = {
template : "template",
pic : { image : data[i].get("imageUrl") },
username : { text : data[i].get("username") }
};
posts.push(post);
}
$.section.setItems(posts);
How can I add tags (that are clickable) to the post if I am supposed to declare EVERY view in the template before hand? Each tags array in my example would need a different number of views depending on the array length. Each tag would ideally be its own UI.Label element. I believe this can be done using a TableView, but I would prefer using ListView for performance reasons.

I think I know what you need, in this case since you want to generate each item dynamically (for example, a scenario where you open your window with your ListView empty first and make an API call to get remote data and fill the ListView with said data) you will need to use ItemTemplates declared in their own controllers.
You just create a new controller like normal and in the view xml you put your ItemTemplate:
<Alloy>
<ItemTemplate name="template" id="template">
<View class="item-container">
<ImageView bindId="pic" class="pic"/>
<Label bindId="username" class="username"/>
</View>
</ItemTemplate>
</Alloy>
In your tss you put all of the styles referred to each element in your template, since you didn't provide a tss example I can't tell what are your style properties, but in the tss you need to define the style of the template, for example lets say something like:
"#template": // this is the id of your template in your xml
{
width : Ti.UI.FILL,
height : '44dp',
backgroundColor : '#FFFFFF'
}
To fill your ListView with ListItems dynamically, you will need to do something like this in your callback from your API:
function displayListItems(items)
{
var itemCollection = [];
for(var i=0; i < items.length; i++)
{
var tmp = {
pic : {
image : items[i].image
},
username : {
text : items[i].text
},
template : 'template' // here goes the name of the template in your xml, **do not confuse name with id, both are different and using one doesn't replace the other**
};
itemCollection.push(tmp);
}
$.ListView.sections[0].items = itemCollection;
}
And voila, you get your ListView filled dynamically. Now there are some extra steps you can do.
In your template controller you can leave it blank since the ListView can manage the itemclick event, but if you want different actions to take place when a certain element in the Listitem to trigger, you need to specify the functions to be called in your controller for each element.
For example lets say you passed a property called dataInfo to your ImageView and your Label in your template like this:
function displayListItems(items)
{
var itemCollection = [];
for(var i=0; i < items.length; i++)
{
var tmp = {
pic : {
image : items[i].image
dataInfo : items[i].fooA //lets pass to the ImageView the object fooA
},
username : {
text : items[i].text,
dataInfo : items[i].fooB //lets pass to the Label the object fooB
},
template : 'template' // here goes the name of the template in your xml, **do not confuse name with id, both are different and using one doesn't replace the other**
};
itemCollection.push(tmp);
}
$.ListView.sections[0].items = itemCollection;
}
And you want the ImageView and the Label to call different functions, you will need to change your xml like this:
<Alloy>
<ItemTemplate name="template" id="template">
<View class="item-container">
<ImageView bindId="pic" class="pic" onClick="imageFunction"/> <!-- added onClick event -->
<Label bindId="username" class="username" onClick="labelFunction"/> <!-- added onClick event -->
</View>
</ItemTemplate>
</Alloy>
In your controller you will declare each function:
function imageFunction(e)
{
var dataInfo;
if(Ti.Platform.osname === 'android')
{
var item = e.section.items[e.itemIndex];
var bindObject = item[e.bindId];
dataInfo = bindObject.fooA;
}
else
{
dataInfo = e.source.fooA;
}
}
function labelFunction(e)
{
var dataInfo;
if(Ti.Platform.osname === 'android')
{
var item = e.section.items[e.itemIndex];
var bindObject = item[e.bindId];
dataInfo = bindObject.fooB;
}
else
{
dataInfo = e.source.fooB;
}
}
Now you might ask, why do check for the operative system name, well that is because Android and iOS receive different e objects even if you use the same function. In iOS whatever property you pass to the source of the event can be accessed directly with e.source.propertyName while in Android you need to access to the item in e.section using e.itemIndex, after that you retrieve the view inside the item with the e.bindId associated to it.
One of the biggest restrictions on ListItems is updating the views inside a ListItem, to do this you need to update the whole item you want to change visually and assign it a different template, but the speed at which this is done you won't be able to notice any lag, seriously ListView's performance is something else, unlike ScrollView and let's not talk about the horrible and buggy TableView.
A warning, as of Titanium SDK 3.2.0.GA there's a bug in ItemTemplates that causes for views inside child views in the template to change their zIndex in Android with no way to control it, there are two known instances for this:
If you use a don't set the layout in a child view: this could cause for a view that should be displayed beneath another view to come on top of it.
If you use a vertical layout in a child view: this could cause for the positions of each view to be scrambled, this is because zIndex alters the order of display in a vertical layout.
This bug is triggered randomly and the Appcelerator team hasn't put much work on it, check the JIRA ticket here TIMOB-16704.
This can be avoided if you use a template with fixed positioned views and making sure no view comes on top of another, also remember no vertical layouts, haven't tested this with horizontal but personally I try to avoid horizontal layouts since there are other bugs related to it when used in scrollviews, normal views, etc.
EDIT
Another thing you might want to do with this is to assign a different look to the items you render, you have to options:
To apply the styles when you declare the ListItem.
To apply a different layout to each ListItem depending on a series of conditions.
For the first option you need to omit or overwrite the declaration of certain properties in your template:
For example, let's use a different background color where the property fooA exists and another color if it doesn't:
function displayListItems(items)
{
var itemCollection = [];
for(var i=0; i < items.length; i++)
{
var properties = {};
if(typeof items[i].fooA !== 'undefined')
{
properties = {
backgroundColor : 'red'
};
}
else
{
properties = {
backgroundColor : 'blue'
};
}
var tmp = {
properties : properties, // properties for the template
pic : {
image : items[i].image
dataInfo : items[i].fooA //lets pass to the ImageView the object fooA
},
username : {
text : items[i].text,
dataInfo : items[i].fooB //lets pass to the Label the object fooB
},
template : 'template' // here goes the name of the template in your xml, **do not confuse name with id, both are different and using one doesn't replace the other**
};
itemCollection.push(tmp);
}
$.ListView.sections[0].items = itemCollection;
}
You can change width, height, backgroundColor, layout, etc. according to your needs.
Now if you want each item to have a distinct look (meaning different views to display different content) and perhaps a different behavior, you'll need to use different templates.
This might sound bothersome but it is not, templates are fast to create once you get used to them which doesn't take long, another downer might be that if you want 11 different looks, that might mean you'll need 11 templates but that's a extreme case and you might want to rethink your UI if you're dealing with that many templates.
Although restrictive, item templates offer a wide array of options for you to use, a little of imagination is the only ingredient necessary to bring out all of the possibilities.
EDIT 2
I finally understood what was you problem, if you need to create a template whose content changes according to a x variable, then you should try declaring the template on your ListView controller, but this should be done before opening the window were you will be showing the ListView since the templates property can only be set on creation, you should add something like:
function createTemplate(items)
{
var template = {};
for(var i=0; i < items.length; i++)
{
template.childTemplates = [];
for(var j=0; items[i].tags.length; j++)
{
var childTemplate = {
type: 'Ti.UI.Label',
bindId: 'tag' + j,
properties : {
width : Ti.UI.SIZE, // Here you define how your style
height : Ti.UI.SIZE,
font : {
fontSize : '18dp'
},
text : items[i].tags[j].text // you can pass the text here or if you want to on the later for
}
};
template.childTemplates.push(childTemplate);
}
}
// After this you should end up with a template with as many childTemplates as tags each item have, so send the template to the controller with your ListView
Alloy.createController('ListViewWindow', {customTemplate: template});
}
And in your ListView controller you retrieve the template:
var args = arguments[0] || {};
var template = args.customTemplate;
$.ListView.templates = {'customTemplate' : template}; // before any window open call, do this
This should add the template to your ListView, you can also create the ListView in your controller instead of declaring it in your Alloy xml, use the one that fits your needs more.

This should be possible with a ListView if you create the template in the controller dynamically. You would also need to iterate through each "tags" object and generate a Ti.UI.Label "type" for each tag item. However, I'm not certain this method will be more efficient than using a TableView object because essentially every ListItem you create will contain a different template.
To generate a dynamic template it would be similar to this below: Keep in mind you will need to iterate over "tags" and generate x Ti.UI.Label types where x is the length of "tags". Also, the click event should work using Titanium SDK 3.2.1.
var plainTemplate = {
childTemplates: [
{
type: 'Ti.UI.Label',
bindId: 'username'
},
{
type: 'Ti.UI.ImageView',
bindId: 'pic'
},
{
type: 'Ti.UI.Label',
bindId: 'tags',
events: { click : handleTagClickEvent } // Binds a callback to click event
}
]};
function handleTagClickEvent(e) {
Ti.API.info('You clicked a tag label: ' + e.type);
}
var listView = Ti.UI.createListView({
templates: { 'plain': plainTemplate },
defaultItemTemplate: 'plain'
});
Hope this helps you in some way!

My fake case statement in Emberjs is blowing up. What's the right way?

I'm trying to render a different handlebars template based on the current value of a property in my model, and there could be quite a few options (hence I'd rather not use a lot of {{#if}}s). The best thing I can think of is this:
Ember.Handlebars.registerBoundHelper('selectorType', function(name, options) {
return Ember.Handlebars.compile("{{template _selectors_" + name + "}}")(options.contexts[0], options);
});
And I use that in my template like:
{{selectorType selector.name}}
(instead of like a hundred {{#if}}s)
The problem is that I get this error during render: "You can't use appendChild outside of the rendering process"
Clearly I'm doing something wrong. What's the right way to do this?

I don't think there's any need to create a helper to do this. You can do it from within the view by modifying the templateName and then calling the rerender method once you've changed its templateName:
init: function() {
this.set('templateName', 'firstOne');
this._super();
},
click: function() {
this.set('templateName', 'secondOne');
this.rerender();
}
We can use the init method for setting the empty templateName before the template has been rendered. We'll then call the _super method to complete the insertion of the view into the DOM. We can then trigger the change of the view on the click event. We update the templateName variable and then call rerender() to re-render this particular view.
I've set you up a JSFiddle as an example: http://jsfiddle.net/pFkaE/ try clicking on "First One." to change the view to the secondOne.

I ended up solving this using a ContainerView with dynamic childViews, see Ember.js dynamic child views for a discussion on how.
The relevant code is (coffeescript):
App.SelectorType = Ember.Object.extend
name: null
type: null
typeView: null
options: null
App.SelectorTypes = [
App.SelectorType.create(
name: 'foo'
type: 'bar'
) #, more etc
]
App.SelectorTypes.forEach (t) ->
t.set 'typeView', Ember.View.create
templateName: "selectors/_#{t.get('viewType')}_view"
name: t.get('name')
App.SelectorDetailView = Ember.ContainerView.extend
didInsertElement: ->
#updateForm()
updateForm: (->
type = #get('type')
typeObject = App.SelectorTypes.findProperty('type', type)
return if Ember.isNone(type)
view = typeObject.get('typeView')
#get('childViews').forEach (v) -> v.remove()
#get('childViews').clear()
#get('childViews').pushObject(view)
).observes('type')
And the template:
Selector Type:
{{view Ember.Select
viewName=select
contentBinding="App.SelectorTypes"
optionValuePath="content.type"
optionLabelPath="content.name"
prompt="Pick a Selector"
valueBinding="selector.type"
}}
<dl>
<dt><label>Details</label></dt>
<dd>
{{view App.SelectorDetailView typeBinding="selector.type"}}
</dd>
</dl>
Seems too hard, though, would be interested to see better solutions!

Backbone View Attribute set for next Instantiation?

I have a view that has a tooltip attribute. I want to set that attribute dynamically on initialize or render. However, when I set it, it appears on the next instantiation of that view instead of the current one:
var WorkoutSectionSlide = Parse.View.extend( {
tag : 'div',
className : 'sectionPreview',
attributes : {},
template : _.template(workoutSectionPreviewElement),
initialize : function() {
// this.setDetailsTooltip(); // doesn't work if run here either
},
setDetailsTooltip : function() {
// build details
...
// set tooltip
this.attributes['tooltip'] = details.join(', ');
},
render: function() {
this.setDetailsTooltip(); // applies to next WorkoutViewSlide
// build firstExercises images
var firstExercisesHTML = '';
for(key in this.model.workoutExerciseList.models) {
// stop after 3
if(key == 3)
break;
else
firstExercisesHTML += '<img src="' +
(this.model.workoutExerciseList.models[key].get("finalThumbnail") ?
this.model.workoutExerciseList.models[key].get("finalThumbnail").url : Exercise.SRC_NOIMAGE) + '" />';
}
// render the section slide
$(this.el).html(this.template({
workoutSection : this.model,
firstExercisesHTML : firstExercisesHTML,
WorkoutSection : WorkoutSection,
Exercise : Exercise
}));
return this;
}
});
Here is how I initialize the view:
// section preview
$('#sectionPreviews').append(
(new WorkoutSectionPreview({
model: that.workoutSections[that._renderWorkoutSectionIndex]
})).render().el
);
How can I dynamically set my attribute (tooltip) on the current view, and why is it affecting the next view?
Thanks

You can define attribute property as a function that returns object as result. So you're able to set your attributes dynamically.
var MyView = Backbone.View.extend({
model: MyModel,
tagName: 'article',
className: 'someClass',
attributes: function(){
return {
id: 'model-'+this.model.id,
someAttr: Math.random()
}
}
})
I hope it hepls.

I think your problem is right here:
var WorkoutSectionSlide = Parse.View.extend( {
tag : 'div',
className : 'sectionPreview',
attributes : {} // <----------------- This doesn't do what you think it does
Everything that you put in the .extend({...}) ends up in WorkoutSectionSlide.prototype, they aren't copied to the instances, they're shared by all instances through the prototype. The result in your case is that you have one attributes object that is shared by all WorkoutSectionSlides.
Furthermore, the view's attributes are only used while the the object is being constructed:
var View = Backbone.View = function(options) {
this.cid = _.uniqueId('view');
this._configure(options || {});
this._ensureElement();
this.initialize.apply(this, arguments);
this.delegateEvents();
};
The _ensureElement call is the thing that uses attributes and you'll notice that it comes before initialize is called. That order combined with the prototype behavior is why your attribute shows up on the next instance of the view. The attributes is really meant for static properties, your this.$el.attr('tooltip', ...) solution is a good way to handle a dynamic attribute.