Adding uniqueness validation support out of the box

lib/couchrest/model/validations.rb

@@ -1,6 +1,11 @@
 # encoding: utf-8
 
 require "couchrest/model/validations/casted_model"
+require "couchrest/model/validations/uniqueness"
+
+I18n.load_path << File.join(
+  File.dirname(__FILE__), "validations", "locale", "en.yml"
+)
 
 module CouchRest
   module Model
@@ -23,8 +28,32 @@ module CouchRest
           validates_with(CastedModelValidator, _merge_attributes(args))
         end
         
-        # TODO: Here will lie validates_uniqueness_of
+        # Validates if the field is unique for this type of document. Automatically creates
-        
+        # a view if one does not already exist and performs a search for all matching
+        # documents.
+        #
+        # Example:
+        #
+        #   class Person < CouchRest::Model::Base
+        #     property :title, String
+        # 
+        #     validates_uniqueness_of :title
+        #   end
+        #
+        # Asside from the standard options, a +:proxy+ parameter is also accepted if you would 
+        # like to call a method on the document on which the view should be performed.
+        #
+        # Examples:
+        #
+        #   # Same as not including proxy:
+        #   validates_uniqueness_of :title, :proxy => 'class'
+        #
+        #   # Person#company.people provides a proxy object for people
+        #   validates_uniqueness_of :title, :proxy => 'company.people'
+        #
+        def validates_uniqueness_of(*args)
+          validates_with(UniquenessValidator, _merge_attributes(args))
+        end
       end
 
     end

lib/couchrest/model/validations/locale/en.yml

@@ -0,0 +1,5 @@
+en:
+  errors:
+    messages:
+      taken: "is already taken"
+

lib/couchrest/model/validations/uniqueness.rb

@@ -0,0 +1,42 @@
+# encoding: urf-8
+
+module CouchRest
+  module Model
+    module Validations
+      
+      # Validates if a field is unique 
+      class UniquenessValidator < ActiveModel::EachValidator
+
+        # Ensure we have a class available so we can check for a usable view
+        # or add one if necessary.
+        def setup(klass)
+          @klass = klass
+        end
+
+
+        def validate_each(document, attribute, value)
+          unless @klass.has_view?("by_#{attribute}")
+            @klass.view_by attribute
+          end
+
+          # Determine the base of the search
+          base = options[:proxy].nil? ? @klass : document.send(options[:proxy])
+
+          docs = base.view("by_#{attribute}", :key => value, :limit => 2, :include_docs => false)['rows']
+          return if docs.empty?
+
+          unless document.new?
+            return if docs.find{|doc| doc['id'] == document.id}
+          end
+          
+          if docs.length > 0
+            document.errors.add(attribute, :taken, :default => options[:message], :value => value)
+          end
+        end
+
+
+      end
+
+    end
+  end
+end

spec/couchrest/validations.rb

@@ -0,0 +1,58 @@
+require File.expand_path("../../spec_helper", __FILE__)
+
+require File.join(FIXTURE_PATH, 'more', 'cat')
+require File.join(FIXTURE_PATH, 'more', 'article')
+require File.join(FIXTURE_PATH, 'more', 'course')
+require File.join(FIXTURE_PATH, 'more', 'card')
+require File.join(FIXTURE_PATH, 'base')
+
+# TODO Move validations from other specs to here
+
+describe "Validations" do
+
+  describe "Uniqueness" do
+
+    before(:all) do
+      @objs = ['title 1', 'title 2', 'title 3'].map{|t| WithUniqueValidation.create(:title => t)}
+    end
+    
+    it "should validate a new unique document" do
+      @obj = WithUniqueValidation.create(:title => 'title 4')
+      @obj.new?.should_not be_true
+      @obj.should be_valid
+    end
+
+    it "should not validate a non-unique document" do
+      @obj = WithUniqueValidation.create(:title => 'title 1')
+      @obj.should_not be_valid
+      @obj.errors[:title].should eql(['is already taken'])
+    end
+
+    it "should save already created document" do
+      @obj = @objs.first
+      @obj.save.should_not be_false
+      @obj.should be_valid
+    end
+
+    context "with a proxy parameter" do
+      it "should be used" do
+        @obj = @objs.first
+        proxy = @obj.should_receive('proxy').and_return(@obj.class)
+        @obj.class.validates_uniqueness_of :title, :proxy => 'proxy'
+        @obj.valid?.should be_true
+      end
+    end
+
+    context "with a pre-defined view" do
+      it "should no try to create new view" do
+        @obj = @objs.first
+        @obj.class.should_not_receive('view_by')
+        @obj.class.should_receive('has_view?').and_return(true)
+        @obj.class.should_receive('view').and_return({'rows' => [ ]})
+        @obj.valid?
+      end
+    end
+  
+  end
+
+end

spec/fixtures/base.rb

@@ -114,4 +114,12 @@ class WithAfterInitializeMethod < CouchRest::Model::Base
 
 end
 
+class WithUniqueValidation < CouchRest::Model::Base
+  use_database DB
+
+  property :title
+
+  validates_uniqueness_of :title
+end
+