Handlebars #unless creates new data context visible to ..

[cscott]

Meteor's implementation of .. in block helpers appears to differ from handlebar's. The handlebars documentation says,

The ../ path segment references the parent template scope, not one level up in the context. This is because block helpers can invoke a block with any context, so the notion of "one level up" isn't particularly meaningful except as a reference to the parent template scope.

but in meteor, {{#unless}} (and presumably {{#if}} as well, though I didn't test this specifically) creates a new data context, and .. refers to the block context chain. Thus, the following behaves surprisingly:

{{#with doc}}
    {{> template1}}
{{/with}}

<template name="template1">
<p>This is what we expect -- the id of doc: {{_id}}</p>
{{#each array_field_of_doc}}}
<p>This is also what we expect -- the id of doc {{../_id}}</p>
{{#unless false}}
<p>This is unexpectedly undefined: {{../_id}}</p>
<p>This is how you have to get the id of doc: {{../../_id}}</p>
{{/unless}}
{{/each}}
</template>

[dgreensp]

Meteor's implementation of .. was never very good.

Meteor's template language is morphing at the moment. Instead of .., we'll have ways of accessing named data in enclosing templates. We'll also better-document the behavior of syntax like this.