Do Rails 3 Active Record dynamic find_or_create finder methods have some undocumented inconsistencies?

Apologies for the long title, but this is bothering me. I'm new to Rails, so this is my first project. Rails 3.0.3.

In my model, a User may or may not have read many Entries; this is tracked in a model called ReadEntries. This many-to-one relationship is properly defined in the code, I think.

User.rb:

has_many :read_entries

Entry.rb:

has_many :read_entries

ReadEntry.rb:

belongs_to :entry
belongs_to :user

This table has to be populated at some point. If I try to do this:

user.read_entries.find_or_create_by_entry_id(entry.id, :read => false)

I get the error Unknown key(s): read. Leave out trying to set :read, and it works.

However, if I create the same row with this, it works:

ReadEntry.find_or_create_by_entry_id_and_user_id(entry.id, user.id, :read => false)

Logically, these methods should be identical, right? Thanks.

I've also had weird experiences with find_or_create. I would love it if it worked, but it seems inconsistent.

I'm currently having the same issue as you, and I think it may be due to calling find_or_create on an association as opposed to the model directly. Here's my example:

    permission_assignments.find_or_create_by_role_id(:role_id => role_id, :is_allowed => false)

This works to create the assignment, except the "is_allowed" field gets set to it's default of "true". This code works for me (in the Permission model, hence the self reference)

    PermissionAssignment.find_or_create_by_permission_id_and_role_id(:permission_id => self.id, :role_id => role_id, :is_allowed => false)

It's more verbose, unfortunately, but it works. The only problem that I still notice is that the object that is returned has no id assigned (the record does get created in the database, however, but if I wanted to update any more attributes I wouldn't be able to without the id). Don't know if that's a separate issue or not.

Rails 3.0.4 here with Postgres 8.4

You cannot pass in other fields like that as Rails will assume they are options for the find. Instead, you will need to make your method call longer:

user.read_entries.find_or_create_by_entry_id_and_read(entry.id, false)

Or alternatively use a shorter, custom syntax for that.

For your final example, my thoughts are that Rails will take the second argument and use that as options. Other than that, I am not sure.