/ Ruby on Rails
/
method

with_scope

with_scope(method_scoping = {}, action = :merge, &block)
protected

Scope parameters to method calls within the block. Takes a hash of method_name => parameters hash. method_name may be :find or :create. :find parameters may include the :conditions, :joins, :include, :offset, :limit, and :readonly options. :create parameters are an attributes hash. 

  class Article < ActiveRecord::Base
    def self.create_with_scope
      with_scope(:find => { :conditions => "blog_id = 1" }, :create => { :blog_id => 1 }) do
        find(1) # => SELECT * from articles WHERE blog_id = 1 AND id = 1
        a = create(1)
        a.blog_id # => 1
      end
    end
  end

In nested scopings, all previous parameters are overwritten by the innermost rule, with the exception of :conditions and :include options in :find, which are merged. 

  class Article < ActiveRecord::Base
    def self.find_with_scope
      with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }, :create => { :blog_id => 1 }) do
        with_scope(:find => { :limit => 10 })
          find(:all) # => SELECT * from articles WHERE blog_id = 1 LIMIT 10
        end
        with_scope(:find => { :conditions => "author_id = 3" })
          find(:all) # => SELECT * from articles WHERE blog_id = 1 AND author_id = 3 LIMIT 1
        end
      end
    end
  end

You can ignore any previous scopings by using the with_exclusive_scope method. 

  class Article < ActiveRecord::Base
    def self.find_with_exclusive_scope
      with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }) do
        with_exclusive_scope(:find => { :limit => 10 })
          find(:all) # => SELECT * from articles LIMIT 10
        end
      end
    end
  end

Note: the :find scope also has effect on update and deletion methods, like update_all and delete_all.

2Notes

:find takes more keys than written

Mange · Jan 14, 2010

The documentation says that the :find keywords "may include the :conditions, :joins, :include, :offset, :limit, and :readonly options". Note that this does not mean that only those options are supported. :sort also works like it should, for example.

Rails 3.2 / 4.x with_scope replacement

aossowski · Dec 29, 2014

If you're looking for with_scope replacement for newer versions, see http://apidock.com/rails/ActiveRecord/Relation/scoping