Query through associations - Rails 3

Question

I'd like to make some queries just like this:

employees = Employee.where(:group.name => 'admin')
employees = Employee.where(:company.address.city => 'Porto Alegre')

I mean, I need to access fields that are in another model via association.

Thanks in advance

Answer 1

assuming a company can have multiple addresses (which I'm assuming because of your company.address.city namespacing, and because it makes for an interesting query example):

class Group < ActiveRecord::Base
  has_many :employees
end

class Employee < ActiveRecord::Base
  belongs_to :group
  belongs_to :company
end

class Company < ActiveRecord::Base
  has_many :employees
  has_many :addresses
end

class Address < ActiveRecord::Base
  belongs_to :company
end

The queries you're looking for would be as follows:

Employee.
  joins(:group).
  where(:groups => { :name => 'admin' })
Employee.
  joins(:company => :addresses).
  where(:addresses => { :city => 'Porto Alegre' })

note that in the where clauses above the plural form of the association is always used. The keys in the where clauses refer to table names, not the association name.