Region: $el set in constructor might be resolved wrongly

[ardi-n]

Description

1. Having a server-generated html structure of a collection I want to initialize it using a CollectionView with any needed nested views.
2. Because child views are identical they have identical region definitions.
3. Regions are initialized before el/$el are resolved for a view.
4. Thus region's $el is resolved wrongly in constructor - parentEl is not yet defined so region's $el is being searched in a whole document resulting in a jQuery collection of as many elements as there are in a list.
5. I can't use region's $el to i.e. search within it for existing html that should be initialized with nested views.
6. Naturally region's $el is fixed after show() is called.

Expected behavior

Region's $el should be usable if it is set in constructor. Regions could be initialized after a view calls setElement.

Environment

1. Marionette version: 3.3.1
2. Backbone version: 1.3.3

[paulfalgout]

I'm pretty sure I follow this, but a fiddle would help.

This would require regions be setup after initialize as well.

Personally I think that the ideal fix would be for regions to never be initialized unless getRegion is called, so they wouldn't be in the constructor at all.

Then I also think that we should remove the DOM lookup from the region altogether. I think ideally the view should pass the el to the region rather than the whole parentEl business.

We might be able to make the getRegion a lazy evaluation without being breaking.

[paulfalgout]

A pretty poor work around for the moment would be to:

regions() {
   this.setElement(this.el);

  return {
    region: '.selector'
  }
}

[ardi-n]

I'll try to deliver a fiddle tomorrow. But this workaround should indeed work.

[ardi-n]

Here's a demo: https://jsfiddle.net/9732v9cx/
The suggested workaround does not work. Only if you call _ensureElement() on a region its $el is fixed.

[paulfalgout]

ah the problem in the workaround is that this.el isn't set until the backbone.view constructor call.. well actually not until the setElement call :-) in this case.. but if you change it to this.getOption('el') it should work.

[JSteunou]

Personally I think that the ideal fix would be for regions to never be initialized unless getRegion is called, so they wouldn't be in the constructor at all.

@paulfalgout that's kind of what I did in my autoregion plugin, and indeed that's way better https://github.com/JSteunou/marionette.autoregion