From 10eac99b443ee6de52d9201f76ddec8bdfa11b19 Mon Sep 17 00:00:00 2001
From: Michael Schuerig <michael@schuerig.de>
Date: Sun, 10 Nov 2013 18:02:34 +0100
Subject: [PATCH] Inherit decorator from superclass.

If the class itself does not have a decorator, try the superclass.
---
 lib/draper/decoratable.rb       | 8 ++++++--
 spec/draper/decoratable_spec.rb | 6 ++++++
 spec/spec_helper.rb             | 1 +
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/lib/draper/decoratable.rb b/lib/draper/decoratable.rb
index 2c39dd6..3771e57 100644
--- a/lib/draper/decoratable.rb
+++ b/lib/draper/decoratable.rb
@@ -75,8 +75,12 @@ module Draper
         decorator_name = "#{prefix}Decorator"
         decorator_name.constantize
       rescue NameError => error
-        raise unless error.missing_name?(decorator_name)
-        raise Draper::UninferrableDecoratorError.new(self)
+        if superclass.respond_to?(:decorator_class)
+          superclass.decorator_class
+        else
+          raise unless error.missing_name?(decorator_name)
+          raise Draper::UninferrableDecoratorError.new(self)
+        end
       end
 
       # Compares with possibly-decorated objects.
diff --git a/spec/draper/decoratable_spec.rb b/spec/draper/decoratable_spec.rb
index 46ef103..023d5d6 100644
--- a/spec/draper/decoratable_spec.rb
+++ b/spec/draper/decoratable_spec.rb
@@ -152,6 +152,12 @@ module Draper
         it "infers the decorator from the class" do
           expect(Product.decorator_class).to be ProductDecorator
         end
+
+        context "without a decorator on its own" do
+          it "infers the decorator from a superclass" do
+            expect(SpecialProduct.decorator_class).to be ProductDecorator
+          end
+        end
       end
 
       context "for ActiveModel classes" do
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 2e3d2a2..9e1334c 100755
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -13,6 +13,7 @@ end
 class Model; include Draper::Decoratable; end
 
 class Product < Model; end
+class SpecialProduct < Product; end
 class ProductDecorator < Draper::Decorator; end
 class ProductsDecorator < Draper::CollectionDecorator; end