- some refactoring

- added support for blocks to generate slugs

Gemfile

@@ -2,3 +2,4 @@ source "http://rubygems.org"
 
 # Specify your gem's dependencies in has_unique_slug.gemspec
 gemspec
+gem 'rspec'

README.md

@@ -7,31 +7,39 @@ Add `gem has_unique_slug` to your Gemfile and run `bundle install` to get it ins
 
 ## Usage
 
-Assume you have a Post model that has a title and slug column in which the slug column is generated from the post title.
+Assume you have a Post model that has a title and slug column, you can use the following to uniquely parameterize title:
 
 	class Post < ActiveRecord::Base
 		has_unique_slug
 	end
 
 
 A unique slug will be generated automatically on creation.  
-If the generated slug is not unique, "-n" is appended onto the end. n starts at 2 and will increment by 1 until a unique slug is found.
-If a slug is provided, one will not be generated, however the same rule applies as the above if the slug is not unique.
+If the generated slug is not unique, a number is added onto the end to endure uniqueness. The series starts at 2 and increments
+up by one until a unique slug is found.
+If a slug is already specified, this slug will be used however the above rules still apply for uniqueness.
 
 You can specify which column to use to generate the slug and which column to use to store the slug. Below is the default:
 
 	class Post < ActiveRecord::Base
-		has_unique_slug :title, :slug
-	end
-
+		has_unique_slug :slug, :title
+	end	
 
-Or if only 1 argument is given, use that column to generate the slug
+Or if only 1 argument is given, use that column to store the slug:
 
 	class Post < ActiveRecord::Base
-		has_unique_slug :name		# Uses the name column to generate the slug
+		has_unique_slug :permalink		# Uses the permalink column to store the slug
 	end
-
+
+Optionally, a block can be provided to generate the slug:
+
+    class Car < ActiveRecord::Base
+        has_unique_slug {|car| "#{car.year} #{car.name}"}
+    end
+Note the space: parameterize will be called on the result of the block to ensure the slug is url friendly.
 
 ## TODO:
 
-Would like to write some tests.
+- Would like to write some tests.
+- Would like to be able to specify scope for uniqueness
+- Possibly consider optimizing the method to ensure uniqueness

lib/has_unique_slug.rb

@@ -5,24 +5,37 @@ def self.included(base)
     base.extend ClassMethods
   end
 
+  # Builds a slug from the subject_column unless a block is specified.
+  # If a block is specified, the result of the block is returned.
+  def build_slug(record, subject_column, &block)
+    ( block_given? ? yield(record) : record[subject_column] ).parameterize
+  end
+
   module ClassMethods
 
-    def has_unique_slug(title_col = "title", slug_col = "slug")
+    def has_unique_slug(*args, &block)
+
+      options = { :scope => nil }
+      options.merge! args.pop if args.last.is_a? Hash
+      slug_column, subject_column = args
+      slug_column ||= :slug
+      subject_column ||= :title
 
       # Add ActiveRecord Callback
-      before_create do |record|
+      before_save do |record|
 
         # Add a slug if slug doesn't exist
-        if record[slug_col].blank?
-          record[slug_col] = record[title_col].parameterize
-        end
+        slug_prefix = record[slug_column].blank? ? build_slug(record, subject_column, &block) : record[slug_column]
 
         # Ensure the current slug is unique in the database, if not, make it unqiue
-        i = 2
-        while not record.class.where("#{slug_col} = ?", record[slug_col]).count.zero? 
-          record[slug_col] = "#{record[slug_col]}-#{i}"
-          i += 1
-        end  
+        test_slug, i = slug_prefix, 1
+        record_scope = record.new_record? ? record.class.scoped : record.class.where("id != ?", record.id)
+        while not record_scope.where("#{slug_column} = ?", test_slug).count.zero? 
+          test_slug = "#{slug_prefix}-#{(i += 1)}"
+        end
+
+        # Set the slug
+        record[slug_column] = test_slug
       end
 
       # Add instance methods to objects using has_unique_slug
@@ -33,11 +46,7 @@ def has_unique_slug(title_col = "title", slug_col = "slug")
       # Add configuration mechanism
       instance_eval <<-EOV
         def slug_column
-          '#{slug_col}'
-        end
-        
-        def title_column
-          '#{title_col}'
+          '#{slug_column}'
         end
       EOV
 

spec/has_unique_slug_spec.rb

@@ -0,0 +1,5 @@
+require 'spec_helper'
+
+describe HasUniqueSlug
+  pending "Write test simulating active record"
+end

spec/spec_helper.rb

@@ -0,0 +1,8 @@
+require 'rubygems'
+require 'bundler/setup'
+
+require 'has_unique_slug' # and any other gems you need
+
+RSpec.configure do |config|
+  # some (optional) config here
+end