update.rb in rom-repository-1.0.0.rc1

- old
+ new

@@ -1,14 +1,19 @@
 module ROM
   class Changeset
     # Changeset specialization for update commands
     #
+    # Update changesets will only execute their commands when
+    # the data is different from the original tuple. Original tuple
+    # is fetched from changeset's relation using `by_pk` relation view.
+    # This means the underlying adapter must provide this view, or you
+    # you need to implement it yourself in your relations if you want to
+    # use Update changesets.
+    #
     # @api public
-    class Update < Changeset
-      # @!attribute [r] primary_key
-      #   @return [Symbol] The name of the relation's primary key attribute
-      option :primary_key, reader: true
+    class Update < Stateful
+      command_type :update
 
       # Commit update changeset if there's a diff
       #
       # This returns original tuple if there's no diff
       #
@@ -19,35 +24,17 @@
       # @api public
       def commit
         diff? ? super : original
       end
 
-      # Return true
-      #
-      # @return [TrueClass]
-      #
-      # @api public
-      def update?
-        true
-      end
-
-      # Return false
-      #
-      # @return [FalseClass]
-      #
-      # @api public
-      def create?
-        false
-      end
-
       # Return original tuple that this changeset may update
       #
       # @return [Hash]
       #
       # @api public
       def original
-        @original ||= relation.fetch(primary_key)
+        @original ||= Hash(relation.one)
       end
 
       # Return diff hash sent through the pipe
       #
       # @return [Hash]
@@ -76,30 +63,20 @@
         diff.empty?
       end
 
       # Calculate the diff between the original and changeset data
       #
-      # @return [Hash[
+      # @return [Hash, Array]
       #
       # @api public
       def diff
         @diff ||=
           begin
             new_tuple = __data__.to_a
             ori_tuple = original.to_a
 
             Hash[new_tuple - (new_tuple & ori_tuple)]
           end
-      end
-
-      # @api private
-      def command
-        command_compiler.(command_type, relation, mapper: false).curry(to_h) if diff?
-      end
-
-      # @api private
-      def default_command_type
-        :update
       end
     end
   end
 end