Question

If I have a model called User that has:

  has_many     :parent_relationships,
               :class_name            => "Relationship",
               :foreign_key           => :child_id,
               :dependent             => :destroy,
               :uniq => true
  has_many     :parents,
               :through               => :parent_relationships,
               :source                => :parent

So, I want to be able to find the Users who have at least one parent. Right now, if I fetch a particular user and I do user.parents, I get the list of parents, but how would I do that in a where clause?

My concern is that right now I am fetching like this:

User.where({:role => 'Teen'})

So, I want to find all the Users whose role is a Teen and who at least have a parent. Also, and to make it more complicated, I have another association that I would like to take into account:

 has_and_belongs_to_many :notifications

And I would like to find those Users who has a notification which name attribute is “email”.

Thanks

Answer 1

A join should do it:

User.joins(:parents).uniq

Since this creates an INNER JOIN, it will only return the records with parents. The uniq removes duplicate records that may be returned by the join.

EDIT:

Your method chaining could work something like this:

User.includes(:notifications).joins(:parents).where(:role => "Teen").where("notifications.name = 'email'")