Fousa Fousa - 1 month ago 6
Ruby Question

Active Record with Delegate and conditions

Is it possible to use delegate in your Active Record model and use conditions like

:if
on it?

class User < ApplicationRecord
delegate :company, :to => :master, :if => :has_master?

belongs_to :master, :class_name => "User"

def has_master?
master.present?
end
end

Answer

No, you can't, but you can pass the :allow_nil => true option to return nil if the master is nil.

class User < ActiveRecord::Base
  delegate :company, :to => :master, :allow_nil => true

  # ...
end

user.master = nil
user.company 
# => nil

user.master = <#User ...>
user.company 
# => ...

Otherwise, you need to write your own custom method instead using the delegate macro for more complex options.

class User < ActiveRecord::Base
  # ...

  def company
    master.company if has_master?
  end

end
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