has_and_belongs_to_many with 4 tables

Hi everyone, i am new to this group, hope someone can help me.

Suppose a DB schema with the following tables: users, documents,
sections, documents_sections_users

How can i implement the has_and_belongs_to_many here? Rails doesn't
seem to extract the dependencies :\

Thanks everyone

bump!

Hi,
It should be from what I guess (you need to give more details):
class User < AR
  has_and_belongs_to_many :documents
end

class Document < AR
  has_and_belongs_to_many :users
  has_and_belongs_to_many :sections
end

class Section < AR
has_and_belongs_to_many :documents
end

and the tables are users, documents, sections, documents_users,
documents_sections