circular relationship - habtm

rubyonrails-talk
1

So I have 2 models: Picture and Comment.

Pictures have many Comments, but I'd like for users to be able to post Pictures in Comments, so Comments will have one Picture (possibly). This creates a kind of circular relationship it looks like, and the only way I could think of to implement this is with has_and_belongs_to_many. Am I right, or is there a better way to do this?

2

Hi --

So I have 2 models: Picture and Comment.

Pictures have many Comments, but I'd like for users to be able to post Pictures in Comments, so Comments will have one Picture (possibly). This creates a kind of circular relationship it looks like, and the only way I could think of to implement this is with has_and_belongs_to_many. Am I right, or is there a better way to do this?

You could just do some judicious association naming -- something like:

class Picture < AR::Base    has_many :comments    belongs_to :comment, :foreign_key => "illustration_id" end

class Comment < AR::Base    belongs_to :picture    has_one :illustration, :class_name => "Picture" end

That way, comment.picture = some_picture would always mean that this comment belongs to that picture, while comment.illustration = some_picture would mean that a given picture belonged to this comment.

Or... you could decide that the comment also belongs to the picture it contains, with a distinct foreign key and so forth, though that might feel a bit inside out.

David