Fix a problem when using scopes with a nil value for the scoped field.

lib/permalink_fu.rb

@@ -117,11 +117,14 @@ def create_unique_permalink
         conditions       << id
       end
       if self.class.permalink_options[:scope]
-        scopes = [self.class.permalink_options[:scope]]
-        scopes.flatten!
-        scopes.each do |scope|
-          conditions.first << " and #{scope} = ?"
-          conditions       << send(scope)
+        [self.class.permalink_options[:scope]].flatten.each do |scope|
+          value = send(scope)
+          if value
+            conditions.first << " and #{scope} = ?"
+            conditions       << send(scope)
+          else
+            conditions.first << " and #{scope} IS NULL"
+          end
         end
       end
       while self.class.exists?(conditions)

test/permalink_fu_test.rb

@@ -129,6 +129,14 @@ def self.exists?(conditions)
   has_permalink :title, :scope => :foo
 end
 
+class ScopedModelForNilScope < BaseModel
+  def self.exists?(conditions)
+    (conditions[0] == 'permalink = ? and foo IS NULL') ? (conditions[1] == 'ack') : false
+  end
+
+  has_permalink :title, :scope => :foo
+end
+
 class OverrideModel < BaseModel
   has_permalink :title
 
@@ -358,4 +366,18 @@ def test_should_update_permalink_if_changed_method_does_not_exist
     @m.validate
     assert_equal 'the-permalink', @m.read_attribute(:permalink)
   end
+
+  def test_should_work_correctly_for_scoped_fields_with_nil_value
+    s1 = ScopedModelForNilScope.new
+    s1.title = 'ack'
+    s1.foo = 3
+    s1.validate
+    assert_equal 'ack', s1.permalink
+
+    s2 = ScopedModelForNilScope.new
+    s2.title = 'ack'
+    s2.foo = nil
+    s2.validate
+    assert_equal 'ack-2', s2.permalink
+  end
 end