I've had big problems with this bug in 2.0.2 & 2.0.3.
In Rails Edge (2.0.3) and 2.0.2, I'm having problems with has_many associations where there are colliding names for id fields. The #{model}_id of the associated record takes the #{model}_id value from the join table, not it's own value.
I have:
Emails
has_many contacts
Contact
has_one :user
has_one :contact, :class_name => 'User' (foreign_key: contact_id)
Join Table, contacts_emails
t.integer :email_id
t.integer :contact_id
Note that a column named "contact_id" is in two tables: contacts and contacts_emails.
If you call emails.contacts, you'll get an array of Contacts, obviously.
The bug is that the array that's returned of Contacts will have contact_id set to the contact_id that's in the joining contacts_emails row, not that's in the contacts row.
-----
Example
contacts_emails
------------------
email_id | contact_id
1 3
contacts
------------------
id | email_id | contact_id
3 1 2
users
------------------
id | first_name
2 User
If you do emails.contacts, one Contact will be returned (which is correct).
emails.contacts[0].contact_id will be 3, not 2 as it should be in the table above.
emails.contacts[0].reload.contact_id will correctly be 2.
This is caused because there is a collision on contact_id. If I change contact's contact_id to contact_user_id, it works perfectly.
