Rails where() clause on model association?

You need to join the accounts table and merge appropriate Account scope:

User.joins(:account).merge(Account.where(:active => true))

Try this:

User.joins(:account).where(:accounts => { :active => true })

Use a where clause in the Account model's association:

class Account < ActiveRecord::Base
  has_many :users, -> {where(active: true)}

The other queries will work, but if you only always care about active users, filtering at the association level will properly encapsulate the filter and save you headaches in the future.

Update:

You can also specify 2 relations on the same table:

 class Account < ActiveRecord::Base
   has_many :users
   has_many :active_users, -> {where(active: true)}, :class_name => 'User'

2nd Update:

After re-reading the question, I now see that my answer didn't answer the question. Here's my answer to the question:

User.where(account: Account.where(active: true))

3rd Update: Here's an example User model that has an active_users attribute

class User < ActiveRecord::Base
  belongs_to :account
  def self.active
    where(account: Account.where(active: true))
  end
end

Doing it this way allows you to put it inline with other user queries:

User.active.where(created_at: (1.week.ago..0.day.ago)).count