Setting default_scope according to some criteria

Question

I'm trying to set default scope according to some criteria determined by ana ActionController before_filter. In controller:

  before_filter :authorize
  ...
  def authorize
    if some_condition
      @default_scope_conditions = something
    elsif another_condition
      @default_scope_conditions = something_else
    end
  end

Inside the ActiveRecord

default_scope :conditions => @default_scope_conditions

But it doesn't seem to work, the before filter gets called but the default_scope doesn't get set. Could you please advise me what I'm doing wrong and how to fix it or suggest me some other way of achieving that.

Answer 1

You set @default_scope_conditions - which is an instance variable from the controller and you expect to read it from the model. It is not visible from the model unless passed as method parameter.

More, this approach would break the MVC principle that separates the model logic from the controller logic: Your model shouldn't automatically access info about current state of the controller.

What you can do: use anonymous scopes.

  def scope_user
    if some_condition
      @default_scope_conditions = something
    elsif another_condition
      @default_scope_conditions = something_else
    end

    @user_scoped = User.scoped(:conditions => @default_scope_conditions)
  end

Then, in your method, you can:

def my_method
  users = @user_scoped.all
end

or

def my_method
  User.with_scope(:conditions => @default_scope_conditions) do
    # .. 
    @users = User.all #users get scoped
    @products.users # also gets scoped
  end
end