From d597e556f4205e7abfe8016c66083944099ea32c Mon Sep 17 00:00:00 2001
From: Bogdan Gusiev <agresso@gmail.com>
Date: Thu, 28 Jun 2012 23:35:16 +0300
Subject: [PATCH] Support inheritence of columns

---
 lib/datagrid/columns.rb       |  8 +++++---
 lib/datagrid/core.rb          | 21 ++++++++++++---------
 spec/datagrid/columns_spec.rb | 13 +++++++++++++
 3 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/lib/datagrid/columns.rb b/lib/datagrid/columns.rb
index 1fd58302..ecba15d5 100644
--- a/lib/datagrid/columns.rb
+++ b/lib/datagrid/columns.rb
@@ -1,4 +1,5 @@
 require "datagrid/utils"
+require "active_support/core_ext/class/attribute"
 
 module Datagrid
 
@@ -10,6 +11,8 @@ def self.included(base)
       base.class_eval do
 
         include Datagrid::Core
+        class_attribute :columns_array
+        self.columns_array = []
 
       end
       base.send :include, InstanceMethods
@@ -21,7 +24,7 @@ def columns(*args)
         options = args.extract_options!
         args.compact!
         args.map!(&:to_sym)
-        (@columns ||= []).select do |column|
+        columns_array.select do |column|
           (!options[:data] || column.data?) && (args.empty? || args.include?(column.name))
         end
       end
@@ -31,8 +34,7 @@ def column(name, options = {}, &block)
         block ||= lambda do |model|
           model.send(name)
         end
-        @columns ||= []
-        @columns << Datagrid::Columns::Column.new(self, name, options, &block)
+        columns_array << Datagrid::Columns::Column.new(self, name, options, &block)
       end
 
       def column_by_name(name)
diff --git a/lib/datagrid/core.rb b/lib/datagrid/core.rb
index 95c7f461..d9ee8de7 100644
--- a/lib/datagrid/core.rb
+++ b/lib/datagrid/core.rb
@@ -1,4 +1,5 @@
 require "datagrid/drivers"
+require "active_support/core_ext/class/attribute"
 
 module Datagrid
   module Core
@@ -6,7 +7,7 @@ module Core
     def self.included(base)
       base.extend         ClassMethods
       base.class_eval do
-
+        class_attribute :scope_value
       end
       base.send :include, InstanceMethods
     end # self.included
@@ -35,10 +36,10 @@ def datagrid_attributes
 
       def scope(&block)
         if block
-          @scope = block
+          self.scope_value = block
         else
           check_scope_defined!
-          @scope.call
+          scope_value.call
         end
       end
 
@@ -47,8 +48,9 @@ def driver
       end
 
       protected
-      def check_scope_defined!(message = "Scope not defined")
-        raise(Datagrid::ConfigurationError, message) unless @scope
+      def check_scope_defined!(message = nil)
+        message ||= "Scope not defined"
+        raise(Datagrid::ConfigurationError, message) unless scope_value
       end
 
     end # ClassMethods
@@ -96,9 +98,10 @@ def paginate(*args, &block)
 
       def scope(&block)
         if block_given?
-          @current_scope = block
+          self.scope_value = block
         else
-          @current_scope ? @current_scope.call : self.class.scope
+          check_scope_defined!
+          scope_value.call
         end
       end
 
@@ -106,8 +109,8 @@ def driver
         self.class.driver
       end
 
-      def check_scope_defined!(message)
-        self.class.check_scope_defined!(message)
+      def check_scope_defined!(message = nil)
+        self.class.send :check_scope_defined!, message
       end
 
     end # InstanceMethods
diff --git a/spec/datagrid/columns_spec.rb b/spec/datagrid/columns_spec.rb
index 01ac2d8b..1720a391 100644
--- a/spec/datagrid/columns_spec.rb
+++ b/spec/datagrid/columns_spec.rb
@@ -60,5 +60,18 @@
     report.rows.last.first.should be_false
   end
 
+  it "should inherit columns correctly" do
+    parent = Class.new do
+      include Datagrid
+      scope { Entry }
+      column(:name)
+    end
+
+    child = Class.new(parent) do
+      column(:group_id)
+    end
+    child.column_by_name(:name).should_not be_nil
+    child.column_by_name(:group_id).should_not be_nil
+  end
 
 end