Adding registers in HABTM relationship.


I have a little problem in a HABTM relationship.
I have this schema:

expedients <---> expedients_documents <---> documents
expedients(HABTM)docuements <-> documetns(HABTM)expedients

From the expedients view, I add a new document, passing as parameter
the expedients ids (maybe more than one).However, at time that I
create the document, I cannot put the values in the table

Should I use nested attributes for this? Im reading about, and i think
that putting in the documents/new view a fields_for :expedients must
complaint this, but I cannot get a correct result.

Thanks, and best regards.

Solved.I write a comment for newbies as me...sorry for the english.

The problem raises from the generation of the join table.This table,
cannot must have a id attribute as a primary key, instead of this,
must have a primary key composed by the two foreign keys.In Rails,
this means a :id => false in the migration like this...

class DocumentosExpedientes < ActiveRecord::Migration
  def self.up
    create_table :documentos_expedientes,:id => false do |t|
      t.integer :documento_id
      t.integer :expediente_id

After this, the only thing that I must do is

documento.expedientes_ids << expedientes #expedientes is a array of

You might as well skip the timestamps as well, as the "HABTM table
with extra fields" functionality disappeared in 2.3.

--Matt Jones