Argument Error: The scope body needs to be callable

Question

I'm working through the 'Ruby On Rails 3 Essential Training' and have received a problem when using name scopes. When finding records and using queries withing the Rails console everything went smoothly until I tried to use a name scope in my subject.rb file. This is my code in the subject.rb file.

Class Subject < ActiveRecord::Base    scope :visible, where(:visible => true)  end    

I saved the .rb file and restarted my Rails console but when I run from my rails console:

subjects = Subject.visible 

I get: ArgumentError: The scope body needs to be callable.

Does anyone know why I'm getting this error.

Answer 1

The scope's body needs to be wrapped in something callable like a Proc or Lambda:

scope :visible, -> {   where(:visible => true) } 

The reason for this is that it ensures the contents of the block is evaluated each time the scope is used.

Answer 2

I got the same error , while before my solution I had a space between where and ( like below

scope :registered , -> { where ( place_id:  :place_id , is_registered: :true ) } 

after i removed the space between where and ( like below i made my page working

scope :registered , -> { where( place_id:  :place_id , is_registered: :true ) }