Question

I’m using Ruby on Rails 3 and I created a few scopes in my object class but when I call them from within my code it returns an error:

irb>Transaction.first.committed

=> undefined method `commited’ for #

object class:

class Transaction < ActiveRecord::Base

 attr_accessible :amount, :description, :published, :task_description_id, :discrete_task_id, :transaction_type

 belongs_to :discrete_task

 scope :committed, where(:transaction_type => "committed")

 scope :obligated, where(:transaction_type => "obligated")

 scope :expensed, where(:transaction_type => "expensed")

end

Answer 1

You can’t call a scope (a class method) on a single Transaction object (an instance).

You would have to do this:

Transaction.committed

You get back an ActiveRelation (essentially an Array, but you can call other scopes on it).

What would you expect Transaction.first.committed to do, anyways? You’d have a single object, and then you’d try to find where its transaction_type is “committed”. You already have the object, so you would call its #transaction_type method.

A scope would bring back all Transaction objects that have a transaction type of committed. If you want an instance method that tells you if a single object is committed, then you’d have to make an instance method like:

def committed?
  transaction_type == "committed"
end

Then you could write:

Transaction.first.committed? # => true