Make grids inheritable

lib/datagrid/columns.rb

@@ -42,6 +42,12 @@ def column_by_name(name)
           col.name.to_sym == name.to_sym
         end
       end
+
+      def inherited(child_class)
+        super(child_class)
+        child_class.columns_array = self.columns_array.clone
+      end
+
     end # ClassMethods
 
     module InstanceMethods

lib/datagrid/filters.rb

@@ -1,3 +1,5 @@
+require "active_support/core_ext/class/attribute"
+
 module Datagrid
   module Filters
 
@@ -29,24 +31,21 @@ def self.included(base)
 
         include Datagrid::Core
         include Datagrid::Filters::CompositeFilters
+        class_attribute :filters
+        self.filters = []
 
       end
       base.send :include, InstanceMethods
     end # self.included
 
     module ClassMethods
 
-      def filters
-        @filters ||= []
-      end
-
       def filter_by_name(attribute)
         self.filters.find do |filter|
           filter.name.to_sym == attribute.to_sym
         end
       end
 
-
       def filter(attribute, *args, &block)
         options = args.extract_options!
         type = args.shift || :default
@@ -73,6 +72,11 @@ def default_filter(attribute)
         end
       end
 
+      def inherited(child_class)
+        super(child_class)
+        child_class.filters = self.filters.clone
+      end
+
     end # ClassMethods
 
     module InstanceMethods

spec/datagrid/columns_spec.rb

@@ -70,6 +70,8 @@
     child = Class.new(parent) do
       column(:group_id)
     end
+    parent.column_by_name(:name).should_not be_nil
+    parent.column_by_name(:group_id).should be_nil
     child.column_by_name(:name).should_not be_nil
     child.column_by_name(:group_id).should_not be_nil
   end

spec/datagrid/filters_spec.rb

@@ -55,6 +55,19 @@ class TheReport
     TheReport.new(:name => 'hello')
   end
 
+  it "should support inheritence" do
+    parent = Class.new do
+      include Datagrid
+      scope {Entry}
+      filter(:name)
+    end
+    child = Class.new(parent) do
+      filter(:group_id)
+    end
+    parent.filters.size.should == 1
+    child.filters.size.should == 2
+  end
+
   describe "allow_blank and allow_nil options" do
 
     def check_performed(value, result, options)