`ActiveRecord::Store` works together with PG `hstore` columns.

This is necessary because as of 5ac2341 `hstore` columns are always stored
as `Hash` with `String` keys. `ActiveRecord::Store` expected the attribute to
be an instance of `HashWithIndifferentAccess`, which led to the bug.

4 files changed, 62 insertions, 14 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/serialization.rb b/activerecord/lib/active_record/attribute_methods/serialization.rb
index 1287de0d0d..5701804168 100644
--- a/activerecord/lib/active_record/attribute_methods/serialization.rb
+++ b/activerecord/lib/active_record/attribute_methods/serialization.rb
@@ -66,6 +66,10 @@ module ActiveRecord
         def type
           @column.type
         end
+
+        def accessor
+          ActiveRecord::Store::IndifferentHashAccessor
+        end
       end
 
       class Attribute < Struct.new(:coder, :value, :state) # :nodoc:
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid.rb
index dab876af14..4babee07b4 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid.rb
@@ -234,6 +234,10 @@ module ActiveRecord
 
             ConnectionAdapters::PostgreSQLColumn.string_to_hstore value
           end
+
+          def accessor
+            ActiveRecord::Store::StringKeyedHashAccessor
+          end
         end
 
         class Cidr < Type
@@ -250,6 +254,10 @@ module ActiveRecord
 
             ConnectionAdapters::PostgreSQLColumn.string_to_json value
           end
+
+          def accessor
+            ActiveRecord::Store::StringKeyedHashAccessor
+          end
         end
 
         class TypeMap
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index c1cc905606..3668aecd4b 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -148,6 +148,10 @@ module ActiveRecord
         @oid_type.type_cast value
       end
 
+      def accessor
+        @oid_type.accessor
+      end
+
       private
 
         def has_default_function?(default_value, default)
diff --git a/activerecord/lib/active_record/store.rb b/activerecord/lib/active_record/store.rb
index 5fc80cdb6d..b841b977fc 100644
--- a/activerecord/lib/active_record/store.rb
+++ b/activerecord/lib/active_record/store.rb
@@ -104,26 +104,58 @@ module ActiveRecord
 
     protected
       def read_store_attribute(store_attribute, key)
-        attribute = initialize_store_attribute(store_attribute)
-        attribute[key]
+        accessor = store_accessor_for(store_attribute)
+        accessor.read(self, store_attribute, key)
       end
 
       def write_store_attribute(store_attribute, key, value)
-        attribute = initialize_store_attribute(store_attribute)
-        if value != attribute[key]
-          send :"#{store_attribute}_will_change!"
-          attribute[key] = value
-        end
+        accessor = store_accessor_for(store_attribute)
+        accessor.write(self, store_attribute, key, value)
       end
 
     private
-      def initialize_store_attribute(store_attribute)
-        attribute = send(store_attribute)
-        unless attribute.is_a?(ActiveSupport::HashWithIndifferentAccess)
-          attribute = IndifferentCoder.as_indifferent_hash(attribute)
-          send :"#{store_attribute}=", attribute
+      def store_accessor_for(store_attribute)
+        @column_types[store_attribute.to_s].accessor
+      end
+
+      class HashAccessor
+        def self.read(object, attribute, key)
+          prepare(object, attribute)
+          object.public_send(attribute)[key]
+        end
+
+        def self.write(object, attribute, key, value)
+          prepare(object, attribute)
+          if value != read(object, attribute, key)
+            object.public_send :"#{attribute}_will_change!"
+            object.public_send(attribute)[key] = value
+          end
+        end
+
+        def self.prepare(object, attribute)
+          object.public_send :"#{attribute}=", {} unless object.send(attribute)
+        end
+      end
+
+      class StringKeyedHashAccessor < HashAccessor
+        def self.read(object, attribute, key)
+          super object, attribute, key.to_s
+        end
+
+        def self.write(object, attribute, key, value)
+          super object, attribute, key.to_s, value
+        end
+      end
+
+      class IndifferentHashAccessor < ActiveRecord::Store::HashAccessor
+        def self.prepare(object, store_attribute)
+          attribute = object.send(store_attribute)
+          unless attribute.is_a?(ActiveSupport::HashWithIndifferentAccess)
+            attribute = IndifferentCoder.as_indifferent_hash(attribute)
+            object.send :"#{store_attribute}=", attribute
+          end
+          attribute
         end
-        attribute
       end
 
     class IndifferentCoder # :nodoc:
@@ -141,7 +173,7 @@ module ActiveRecord
       end
 
       def load(yaml)
-        self.class.as_indifferent_hash @coder.load(yaml)
+        self.class.as_indifferent_hash(@coder.load(yaml))
       end
 
       def self.as_indifferent_hash(obj)