Defining table name for has_many self joins in rails?

问题

I wish to set up nested comments, and want to use self-join to set this up.

class Comment < ActiveRecord::Base

has_many :children, :class_name => 'Comment'

#...
end

Now, what sql table structure would I use to set up the has_many self-join?

I'm assuming something like this:

comment_to_comments:
parent_id integer
child_id integer

How do I tell rails to use this table? How do I tell rails that parent_id is the foreign key to reach the parent and the child_id is the foreign key to reach the child?

回答1:

create_table :comments do |t|
  t.integer :parent_id
end

class Comment < ActiveRecord::Base
  has_many :children, :class_name => "Comment", :foreign_key => :parent_id
  belongs_to :parent, :class_name => "Comment"

end

I suggest you use plugin to implement this feature.like awesome_nested_set or acts_as_tree.

来源：https://stackoverflow.com/questions/8736955/defining-table-name-for-has-many-self-joins-in-rails