about nested resources

rubyonrails-talk
1

Hi all,

  I have several resources:

  map.resources :articles, :has_many => [:comments]   map.resources :movies, :has_many => [:comments]   map.resources :photos, :has_many => [:comments]

  all of them have a nested resource named comments, new comments are able to be created by POST to URLs like article_comments_url. My problem is, when I'm in the comments_controller, how can I know which resource this comment belongs to? By reading the params? I think this is not decent, are there any better ways? Thanks in advance!

Cheers, Difei

2

Difei,

If a comment only belongs to either an article, movie or a photo (never more than one) you could add methods in the model to determine which it is for.

For example:

class Comment

  def article_comment?     !article_id.nil?   end end

@comment.article_comment? will return true if this is a comment for an article and false if not.

You could render your view accordingly for each type of comment.

Hope that helps?

3

Ah - I think I understand now.

I would add a column to the comments table called 'kind' (as in, 'kind of comment')

The column should be an integer column with limit 1.

Then assign a different integer value to determine what kind of comment it is.

i.e., 1 = article 2 = photo 3 = movie

When you creating a new comment, simply check the value of this integer and redirect accordingly.

Does that help?

4

That seems like a fine solution.

what about just creating three different types of comments, article_comment, movie_comment, photo_comment?

I'm not necessarily advocating for this, but it's an option, and it may be better. That way, you don't need the functions at all. and it should help keep your controllers & views simple.

There is in some sense a problem of code duplication between the three comment resources, but you may be able to DRY this up with helper methods.

-Gabe

5

Hypothetically, if one were to create three different types of comment would you just create a Comment model and then three other models that were subclasses?

I've never played with subclasses in a rails app (other than the ones specified by rails) so I'm curious as to which whether this would be the way to do it?

Gav

6

Hi all,

  Since my commentable resources are not too many, I decided to do something like this in the comment controller:

before_filter: find_resource

private def find_resource   if params[:article_id]     @resource = Article.find(params[:article_id])   elsif params[:photo_id]     @resource = Photo.find(params[:article_id])   end end

Thank y'all, Difei