add docs to AR::AttributeMethods::BeforeTypeCast [ci skip]

1 files changed, 23 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/before_type_cast.rb b/activerecord/lib/active_record/attribute_methods/before_type_cast.rb
index 7fe5411a3b..faee99ccd1 100644
--- a/activerecord/lib/active_record/attribute_methods/before_type_cast.rb
+++ b/activerecord/lib/active_record/attribute_methods/before_type_cast.rb
@@ -1,5 +1,28 @@
 module ActiveRecord
   module AttributeMethods
+    # = Active Record Attribute Methods Before Type Cast
+    #
+    # <tt>ActiveRecord::AttributeMethods::BeforeTypeCast</tt> provides a way to
+    # read the value of the attributes before typecasting and deserialization.
+    #
+    #   class Task < ActiveRecord::Base
+    #   end
+    #
+    #   task = Task.new(id: '1', completed_on: '2012-10-21')
+    #   task.id           # => 1
+    #   task.completed_on # => Sun, 21 Oct 2012
+    #
+    #   task.attributes_before_type_cast
+    #   # => {"id"=>"1", "completed_on"=>"2012-10-21", ... }
+    #   task.read_attribute_before_type_cast('id')           # => 1
+    #   task.read_attribute_before_type_cast('completed_on') # => "2012-10-21"
+    #
+    # In addition to #read_attribute_before_type_cast and #attributes_before_type_cast,
+    # it declares a method for all attributes with the <tt>*_before_type_cast</tt>
+    # suffix.
+    #
+    #   task.id_before_type_cast           # => "1"
+    #   task.completed_on_before_type_cast # => "2012-10-21"
     module BeforeTypeCast
       extend ActiveSupport::Concern