Hoopla!

Dr. Nic threw down the guantlet about submitting a patch to the scope_out plugin to allow the use of the ActiveRecord::Base#count() method within a scope.

I’m just not sure why it hadn’t occurred to me to submit a patch before extending the plugin. Perhaps I was trying to show off my Ruby-fu, perhaps I didn’t realize GoogleCode allowed patch submissions, or perhaps I’m just trying to artificially raise my post count by doing them separately.

Patching a plugin is dead easy. Knowing which tools to use is about the only tough part.

1. Check out the plugin (svn checkout http://scope-out-rails.googlecode.com/svn/trunk/ scope-out-rails)
2. in your shell change the current working directory to the root of the plugin (cd scope-out-rails)
3. Edit the file that you want changed. For this job it’s ./lib/scope_out.rb
4. type ‘svn diff’ and take a look at what shows up. Does that look about right?
5. type ‘svn diff > my_clearly_named_patch.diff’ to create a patch file from your changes.
6. upload your patch to the project (http://code.google.com/p/scope-out-rails/issues/detail?id=10)

It’s far less work to make a patch than work around the problem:

Index: lib/scope_out.rb
===================================================================
--- lib/scope_out.rb    (revision 29)
+++ lib/scope_out.rb    (working copy)
@@ -112,6 +112,10 @@
         def find_#{name}(*args)
           with_#{name} {find(*args)}
         end
+        
+        def count_#{name}(*args)
+          with_#{name} {count(*args)}
+        end

         def calculate_#{name}(*args)
           with_#{name} {calculate(*args)}

Update: For shame! Here I go spewing out a patch without any tests! Many thanks to Duncan for pointing this out.

The new patch (uploaded to the scope_out project):

Index: test/scope_out_test.rb
===================================================================
--- test/scope_out_test.rb      (revision 29)
+++ test/scope_out_test.rb      (working copy)
@@ -173,6 +173,17 @@
                  Student.calculate_freshmen_active(:count, :all))
   end

+  def test_count_methods
+    assert_equal(Student.count(:conditions => "level = 'Freshman'"),
+                 Student.count_freshmen)
+    assert_equal(Student.count(:conditions => "age = 18"),
+                 Student.count_eighteen_year_olds)
+    assert_equal(Student.count(:conditions => ["active = ?", true]),
+                 Student.count_active)
+    assert_equal(Student.count(:conditions => ["active = ? and level = ?", true, 'Freshman']),
+                 Student.count_freshmen_active)
+  end
+  
   def test_passes_limit_option_to_with_scope
     assert_equal(Student.find_all_by_active(true, :limit => 1), Student.find_one_active(:all))
   end
Index: lib/scope_out.rb
===================================================================
--- lib/scope_out.rb    (revision 29)
+++ lib/scope_out.rb    (working copy)
@@ -112,6 +112,10 @@
         def find_#{name}(*args)
           with_#{name} {find(*args)}
         end
+        
+        def count_#{name}(*args)
+          with_#{name} {count(*args)}
+        end

         def calculate_#{name}(*args)
           with_#{name} {calculate(*args)}