Rails where() clause on model association?

Suppose I have an Account model which has_many Users. Accounts have a boolean "active" column. How can I get all Users that belong to "active" accounts?

@users_of_active_accounts = User.?

Thanks!

Try this:

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

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

User.joins(:account).merge(Account.where(: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

Try this:

Account.includes(:users).where(active: true)

A gem that exists to do that: activerecord_where_assoc (I'm the author)

With it, you can do what you want this way:

@users_of_active_accounts = User.where_assoc_exists(:account, active: true)

And if you have a scope on Account for active, you could call it this way:

@users_of_active_accounts = User.where_assoc_exists(:account, &:active)

So now, if you want, you can make a nice scope for this:

class User < ActiveRecord::Base
  belongs_to :account
  
  scope :active_account, -> { where_assoc_exists(:account, active: true) }
end

@users_of_active_accounts = User.active_account

Read more in the documentation. Here is an introduction and examples.