Dynamic property access with mustache and stache

[zkat]

VOTE HERE

I've been working on converting a lot of EJS templates to mustache recently, and have found one particular pattern that I think might be worth addressing with a built-in solution.

Right now, without writing your own helper, you can't access a data property in mustache based on another property in the scope. Something like <%= car.attr(part); %> in EJS has no direct equivalent in mustache. To pull off the same task, you would need to write a helper, but that is only of limited utility.

This, for example, would still be fairly hard to translate:

<% things.attr(key).each(function(keyedThing) { %>
...
<% } %>

My first instinct is to propose a syntax extension that follows JavaScript conventions for dynamic field access: obj[key], so you would be able to write the following to translate the above without losing the utility of #each:

{{#each things[key]}}
...
{{/each}}

[justinbmeyer]

That seems fine to me. @andykant ? I would check mustache / Handlebars for any existing conventions.

Added this to the 2.2 milestone.

[zkat]

http://handlebarsjs.com/builtin_helpers.html Mentions a helper called lookup. I think in order to really be able to use something like that, we'd need nested helper support. The following then would do the trick nicely while still making [] available for escapes (see #1344) and fitting in more with how handlebars does things. I don't know if there's an issue for that yet, and searching failed me, but see:

{{#each (lookup things key)}}
...
{{/each}}

Either way, probably good for us to include the lookup helper by default since it's default in handlebars.

[justinbmeyer]

Closing for: canjs/can-stache#7