Develop Reference

Handelbars variables via Handlebars.registerPartial

I have a Handelbars app that loads data from javascript and partials for the templates. To get the templates to work I use the following in the Javascript:
var data = require('partials/data.js');
Handlebars.registerPartial('data', data);
Then in my partial I am able to do:
{{> data }}
I have a Handelbars variable I can use in my main template but I want to pass it down to the partial. With my other partials that don't register via the Javascript this is possible. I am assuming I need to pass this variable down like I do the templates?

As per the handlebars documentation, you should be able to simply pass the variable down as a parameter, like so:
{{> data parameter=variable }}

[Ember.js]Pass template helpers created by template helpers as a attribute to a component in order to use it in the components template?

I am using paper-data-table which is a extension to ember-paper.
Both use a technique I did not see before which I would describe as "template helpers create template helpers".
Here is a simple example of the ember-paper toolbar component
{{#paper-toolbar as |toolbar|}}
{{#toolbar.tools}}
{{#paper-button}}
Go Back
{{/paper-button}}
<h2>Toolbar with Standard Buttons</h2>
<span class="flex"></span>
{{#paper-button raised=true}}
Learn More
{{/paper-button}}
{{#paper-button mini=true aria-label="Favorite"}}
{{paper-icon "favorite"}}
{{/paper-button}}
{{/toolbar.tools}}
{{/paper-toolbar}}
There is a new template helper created {{#paper-toolbar as |toolbar|}}.
In my use-case I want to pass the row template helper which is created by the paper-data-table template helper(/component?) down to another component to encapsulate the logic inside it.
I tried to pass it down as a argument:
{{#paper-data-table
sortProp='sort'
sortDir='asc'
as |table|
}}
{{#table.body as |body|}}
{{#each questions as |question index|}}
{{question-row
row=body.row
}}
{{/each}}
{{/table.body}}
{{/paper-data-table}}
But when trying to use the helper(/component) in the template of the question-row component
{{#row as |row|}}{{/row}}
I get the following error:
Assertion Failed: A component or helper named "row" could not be found Error
So I wanted to ask if thats possible and how that would work.

This method is called contextual components and I was able to solve it with the following code in my question-row component:
{{#component row as |row|}}
{{#row.cell}}
HALLO
{{/row.cell}}
{{/component}}

Ember template convention

I'm trying to understand EmberJS template convention in Discourse.
Here's a snippet from app/assets/javascripts/discourse/templates/discovery/categories.hbs
{{#discovery-categories refresh="refresh"}}
{{component controller.categoryPageStyle
categories=model.categories
latestTopicOnly=controller.latestTopicOnly
topics=model.topics}}
{{!-- my-template --}}
{{/discovery-categories}}
What is the meaning of discovery-categories and component?
For example I want to insert my-template to extend categories.hbs, what is the convention I should use to create file with my template?

discovery-categories is the name of the component which is
called statically using the name of the component.
Whereas in the second line 'component' is a template helper which loads the component dynamically using the name specified via property controller.categoryPageStyle.
3.my-template is the yield block , where you can have context of the component discovery-categories if its yield.
for eg. if discovery-categories has a property foo you can write something like
{{#discovery-categories refresh="refresh" foo="Some Text"}}
{{component controller.categoryPageStyle
categories=model.categories
latestTopicOnly=controller.latestTopicOnly
topics=model.topics}}
{{foo}}
{{/discovery-categories}}

How to access data inside if statement in Handlebars templates

To the handlebars (version 1.0.0-rc.3) template I am passing two variables , one is the json and the other one is the string containing the current language on site.
self.template = template({ data: self.model, lang:self.lang });
Then inside the template file I have the following structure:
{{#each data}}
//this is working
{{../lang}}
{{#if this.title}}
{{this.desc}}
//i've tried this
{{../lang}}
//and this
{{lang}}
{{/if}}
{{/each}}
...but I couldn't access the lang value inside the if statement. What am I doing wrong?

I know you already solved your issue with a workaround but registering a Helper for doing a native way is cumbersome.
The thing is that every Handlebars helper overwrites the context and nest the new one inside the parent one, so you have to go up uone step further, like a UNIX like directory.
So, to access lang inside an each->if you have to use:
{{ ../../lang }}

I've find a solution by creating a handlebars helper function:
Handlebars.registerHelper('language', function() {
return self.lang; });
Then in the template i could use {{language}}
where ever I want.

How do I load a model from ember-data into a handlebars.js template?

I have an Ember.js app that gets its data from a JSON resource, and puts it into an ember-data model (Not sure about the terminology) for use in a Handlebars.js view. When I try to put the data into the template context, I get this error:
TypeError: arrangedContent.addArrayObserver is not a function
I've made a Fiddle to demonstrate it. Use the actual Fiddle to view the code, use the following link to see the error (which makes it try to put data into the template/view):
http://fiddle.jshell.net/WZ4vt/show/#/item/1
s = App.store.find(App.Item, 1);
s.get('value1');
The above works fine, and returns "test".

I updated the fiddle: http://jsfiddle.net/WZ4vt/3/
Your mistake was to declare your ItemController as ArrayController, but your Data Store just returned a single entity. I fixed that and additionally your Handlebars Template, as this was not working either.
So this is the new controller declaration:
ItemController: Em.Controller.extend(),
And the updated Template:
<script type="text/x-handlebars" data-template-name="item">
{{content.value1}}
{{content.value2}}
</script>​
Here the working link: http://fiddle.jshell.net/WZ4vt/3/show/#/item/1