1 files changed, 11 insertions, 2 deletions
diff --git a/activerecord/lib/active_record/attribute.rb b/activerecord/lib/active_record/attribute.rb
index 51e4fae62e..48b50d9017 100644
--- a/activerecord/lib/active_record/attribute.rb
+++ b/activerecord/lib/active_record/attribute.rb
@@ -51,7 +51,7 @@ module ActiveRecord
     end
 
     def changed_in_place_from?(old_value)
-      type.changed_in_place?(old_value, value)
+      has_been_read? && type.changed_in_place?(old_value, value)
     end
 
     def with_value_from_user(value)
@@ -78,12 +78,21 @@ module ActiveRecord
       false
     end
 
+    def has_been_read?
+      defined?(@value)
+    end
+
     def ==(other)
       self.class == other.class &&
         name == other.name &&
         value_before_type_cast == other.value_before_type_cast &&
         type == other.type
     end
+    alias eql? ==
+
+    def hash
+      [self.class, name, value_before_type_cast, type].hash
+    end
 
     protected
 
@@ -152,6 +161,6 @@ module ActiveRecord
         false
       end
     end
-    private_constant :FromDatabase, :FromUser, :Null, :Uninitialized
+    private_constant :FromDatabase, :FromUser, :Null, :Uninitialized, :WithCastValue
   end
 end