From 5db0781a6adeeb1b7f6c43955c65ec4abdf5def7 Mon Sep 17 00:00:00 2001
From: Yuki Nishijima <mail@yukinishijima.net>
Date: Mon, 15 Dec 2014 00:03:16 -0500
Subject: [PATCH] Merge pull request #634 from kouyaf77/bugfix

Fixed a bug where paginates_per does not work with subclasses on mongoid
---
 lib/kaminari/models/mongoid_extension.rb | 29 ++++++++++++++++++------
 spec/fake_app/mongoid/models.rb          |  8 +++++++
 spec/models/mongoid/mongoid_spec.rb      | 12 ++++++++++
 3 files changed, 42 insertions(+), 7 deletions(-)

diff --git a/lib/kaminari/models/mongoid_extension.rb b/lib/kaminari/models/mongoid_extension.rb
index eb50cd0..2ebbc84 100644
--- a/lib/kaminari/models/mongoid_extension.rb
+++ b/lib/kaminari/models/mongoid_extension.rb
@@ -7,13 +7,28 @@ module Kaminari
       include Kaminari::ConfigurationMethods
 
       included do
-        # Fetch the values at the specified page number
-        #   Model.page(5)
-        scope Kaminari.config.page_method_name, Proc.new {|num|
-          limit(default_per_page).offset(default_per_page * ([num.to_i, 1].max - 1))
-        } do
-          include Kaminari::MongoidCriteriaMethods
-          include Kaminari::PageScopeMethods
+        Kaminari::MongoidExtension::Document.send(:define_scope, self)
+
+        class << self
+          def inherited_with_kaminari(kls)
+            inherited_without_kaminari(kls)
+            Kaminari::MongoidExtension::Document.send(:define_scope, kls)
+          end
+          alias_method_chain :inherited, :kaminari
+        end
+      end
+
+      private
+      def self.define_scope(kls)
+        kls.class_eval do
+          # Fetch the values at the specified page number
+          # Model.page(5)
+          scope Kaminari.config.page_method_name, Proc.new {|num|
+            limit(default_per_page).offset(default_per_page * ([num.to_i, 1].max - 1))
+          } do
+            include Kaminari::MongoidCriteriaMethods
+            include Kaminari::PageScopeMethods
+          end
         end
       end
     end
diff --git a/spec/fake_app/mongoid/models.rb b/spec/fake_app/mongoid/models.rb
index b2da0fd..d917b2d 100644
--- a/spec/fake_app/mongoid/models.rb
+++ b/spec/fake_app/mongoid/models.rb
@@ -12,6 +12,14 @@ class User::Address
   include ::Mongoid::Document
 end
 
+class Product
+  include ::Mongoid::Document
+end
+
+class Device < Product
+  paginates_per 100
+end
+
 class MongoMongoidExtensionDeveloper
   include ::Mongoid::Document
   field :salary, :type => Integer
diff --git a/spec/models/mongoid/mongoid_spec.rb b/spec/models/mongoid/mongoid_spec.rb
index b599237..41ff832 100644
--- a/spec/models/mongoid/mongoid_spec.rb
+++ b/spec/models/mongoid/mongoid_spec.rb
@@ -207,5 +207,17 @@ if defined? Mongoid
         its(:total_pages) { should == 2 }
       end
     end
+
+    describe '#paginates_per' do
+      context 'when paginates_per is not defined in superclass' do
+        subject { Product.all.page 1 }
+        its(:limit_value) { should == 25 }
+      end
+
+      context 'when paginates_per is defined in subclass' do
+        subject { Device.all.page 1 }
+        its(:limit_value) { should == 100 }
+      end
+    end
   end
 end