/ Ruby on Rails
/
method

with_scope

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

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. 

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

In nested scopings, all previous parameters are overwritten by inner rule except :conditions in :find, that are merged as hash. 

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

You can ignore any previous scopings by using with_exclusive_scope method. 

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

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