Question

I’d like to write a Rails 3 scope, on Client, to do the following:

select * from clients c, dependents d
where d.last_name like '%ss%' and c.id = d.client_id;

Dependent model:

class Dependent < ActiveRecord::Base
  belongs_to :client
  scope :by_last_name, (lambda do |name| { :conditions => ['last_name LIKE ?', "#{name}%"]} end )

Client model:

class Client < ActiveRecord::Base
  has_many :dependents, :dependent => :destroy

I have not yet been able to get a scope join to work syntactically. The dependent’s last name needs to be passed in as a parameter.
Thanks.

Answer 1

Try this:

class Client < ActiveRecord::Base
  scope :by_last_name, lambda { |last_name| includes(:dependents).where("dependents.last_name LIKE ?", "#{last_name}%") }

then call

Client.by_last_name "last_name"

Edit: Changed the code to reflect your problem.
Also find_by_id(1) is the same as find(1) except that it does not throw an error when nothing is found, instead it returns nil.