Problem with RoR's controller getting too large

Let’s assume that there are two models Post and Comment. If we have a
controller dealing with both of these models, it wouldn’t take long
before the controller grows too big to maintain. As far as I
understand, this happens because a controller tries to handle all the
actions allowed by the user. If I change the perspective and create a
controller per model the controller getting too large is fixed but I
have another problem.

I don’t see any good way of accessing multiple controllers (or models)
in one view. There are times when I have to see an instance of a Post
“AND” the comments which belongs to the post. I’ve heard that it can
be solved by using components but that has been deprecated and I’ve
heard that there are some issues which discourage its use. Using
application.rb doesn’t really help because it still makes the
controller grow large. Is there any clean solution to this?

I am not sure what the problem is.

You can structure the application any way you would like. You can
have 200 controllers each handling any part of the user actions you
like. ROR does not impose any restrictions on this.

If you are asking about generated scaffolds then I can suggest that
you build your own pages or use a better scaffolding like
ActiveScaffold. If you are asking about best practices I can suggest
some things to think about:

  1. When a simple structure becomes too large or unmanageable you need
    to partition the functions.
  2. Partitioning works best when you can cleanly separate some things
    from another.
  3. One common partitioning is to place all CRUD actions for one model
    in a controller. But, this is only one strategy.
  4. Another approach is to partition based on use cases. You could put
    all ATM functions in one controller, all teller functions in another,
    all branch manager functions in another, even though all controllers
    deal with the same model classes. This is just another strategy.
  5. Another strategy is to combine 3&4 for sets of classes that are
    tightly coupled.

While most of the scaffolding systems support 3 it is not necessarily
the best. Strategy 4 is actually better in my opinion as it couples
the logical functions together rather than the mere fact that they
share data. Probably the ideal would be to have each use case in its
own controller so that all the steps in a logical process are close
together. This assumes that the application is more than just CRUD
actions, as simple CRUD would not create a controller size problem.


Let me rephrase the problem.

I wish to be able to show an article using postcontroller.
I would also like to create a comment using commentcontroller.
I want to see them both in one view.

related thread:

On 5/2/07, shurain [email protected] wrote:

Let me rephrase the problem.

I wish to be able to show an article using postcontroller.
I would also like to create a comment using commentcontroller.
I want to see them both in one view.

I’m not sure what the issue is. Michael is correct when he says you
have as many controllers as you like.

If you want to see both a post and comment in one view use partials

eg something like (posts)

def show
@post = Post.find_by_id( :id )

in your view

<%= display stuff for posts -%>

<%= render :partial => ‘/comment/detail’, :collection => @post.comments

Is that along the lines of what your after?

My thoughts have been settled, thx everyone.

Helpers and model associations (has_many, belongs_to, etc) may be what
you could look in-to for the future. You could then do something like:

post = Post.find(:first)

A post model can have many comments (has _many :comments) giving you
access to those comments through the associations in the models.


By making a controller for each model, this doesn’t mean you can’t
deal with other models in the views related to that controller.

In your situation, your comment controller may have only 3 actions:
create, update, and destroy, all of which are reached through form
submissions. In that case, your comments controller would control no

But this is fine – put actions in the comment controller which
primarily deal with comments, and actions in the posts controller
which primarily deal with posts. That’s the best you, or any of us,
can do – and it works just fine.

– Eric

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