Idiomatic way to handle nested objects?

Note: this is a repost of {{control}} vs itemController. I think the title I chose was misleading. It looked like a technical question regarding a yet to be finalized feature. It is not. It is actually (I think) fairly generic.

If you use Ember to front end a relational DB based back end, there is a good chance you need to deal with tons of nested objects.

It seems to me not all objects in a hierarchy need their own controller. Some do, some don’t, some just need an ArrayController.

Is there a conventional/idiomatic way to handle this? Could you guys share recommendations?

If we consider a simple example:

 Post hasMany Comments
 Author belongsTo Comment

How do you render a Post with its “descendants” (if there can be a “standard” approach)?

My first take was:

… post template...
{{#each comments}}
 {{ partial 'comment' }} // Say I don't need a controller for each comment

… comment template...
// If you need a controller for your author, how do you handle this? 
// {{ partial }} won't help, and {{ control }} won't work.

It seems like a fairly standard use case to me. So the fact I am stuck make me think I am doing something wrong. To quote the PeepCode screencast:

“If you find that something is difficult to do [in Ember] or requires significant configuration away from the defaults, it should be a signal to you that you might be going in the wrong direction.”

Could you guys shed some light on this?

Thank you!


This is a great post for StackOverflow. It would be great if you could repost it there. Thanks!

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Upon further consideration, I’ve decided to reopen this. It seems that this issue may merit a little more discussion that SO generally affords.

As @wycats said here you can actually use {{render "comment" this}} multiple times. It only uses a singleton controller when you don’t give it a model.

You can also use that in the comment template, but this also brings a question. Why do you want to extract the author logic from the comment at all? If I imagine something like Discourse and it’s replies

I don’t think the author box is reusable, since it always looks a bit different in different parts of the site.

But maybe I’m missing something here? :slight_smile:

Thanks @darthdeus. The post/comment/author example I gave was just theoretical - and probably a bit too simplistic…

But your comment made me think:

I don’t think the author box is reusable, since it always looks a bit different in different parts of the site.

My rule of thumb so far has been: if I want to give to the user the ability to apply certain actions to the representation of a model, it needs to get its own controller, independently of how the model “looks” in different parts of the app.

If we still use the same example: let’s say I want to give the ability to “follow” an author. It should be possible whether the author is shown within a comment, or separated.

With my current “rule”, it would mean I would want my author object to have its own controller all the time.

But am I going in the wrong direction with this? Should it be approached differently in the context of Ember?

Thanks! PJ

What is the conclusion of this discussion? I am facing similar issues with the lack of support for child controllers in Ember, or am I approaching this problem in the wrong direction?