ActiveRecord: Counting associations

I have two tables with a has_one <--> be开发者_如何转开发longs_to relationship: 'user' and 'account'. (An account must have a user, but a user need not have any accounts).

What I'd like to do is return all users who have no accounts...and I'm having a little trouble doing it gracefully. Is there a simple way to do this?

Many thanks...

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You have to join the accounts table into the users table then check for an empty account. In Rails 3, you can do it like this:

User.includes(:account).where('accounts.id' => nil).all

In Rails 2, you can do it like this:

User.find(:all, :include => [ :account ], :conditions => { 'accounts.id' => nil })