[BUGFIX beta] Add special values to {{each}}'s keyPath.

[rwjblue]

Adds the following special values:

• @index - The index of the item in the array.
• @item - The item in the array itself. This can only be used for arrays of strings or numbers.
• @guid - Generate a unique identifier for each object (uses Ember.guidFor).

Makes a couple fixes to allow numeric values from the provided path (many databases use auto-incrementing numbers as id's).

[knownasilya]

Sweetness! Great job @rwjblue

[ilkkao]

@rwjblue This logic should be added also here:

ember.js/packages/ember-htmlbars/lib/helpers/-legacy-each-with-controller.js

Line 24 in bfcc15e

var key = keyPath ? get(item, keyPath) : String(i);

Noticed with this template. Not sure btw why legacy-each is used.

{{#each model key="windowId" as |window|}}
    {{foo-component content=window}}
{{else}}
   ...
{{/each}} 

In any case legacy each should support same special key values, otherwise it's too confusing. I can try to create a PR during the weekend if you like. Logic should be put to a separate module, not copy pasted?

[ilkkao]

PR here #11353

[rwjblue]

Thank you for the PR for this! I do not think the snippet above should be falling into the legacy each case though. Can you double check and open an issue if it is?

[ilkkao]

Right, I'll investigate more and report if it really happens.

[ilkkao]

@rwjblue In my case I was doing model=this on upper layer where this was ArrayController (I had forgot to convert it to Ember.Controller). All good.