make sure validation rules always have 3 parameters

updated the validation docs to reflect this; also updated the example

docs/classes/validation.html

@@ -345,21 +345,23 @@ <h3><a name="errors">Error messages</a></h3>
             <h3><a name="methods">Extending Validation class</a></h3>
 
             <p>There are few aproaches to extend the validation class:</p>
-            
+
             <p>1. To extend the core class like described in the <a href="../general/extending_core.html">Extending Core Classes</a></p>
-            
+
             <p>2. To create a class in <b>app/classes/myvalidation.php</b> (for example)</p>
             <pre class="php"><code>// app/classes/myvalidation.php
 class Myvalidation {
-    
-    public function _validation_unique($val, $options)
+
+    public function _validation_unique($val, $options, $object)
     {
         list($table, $field) = explode('.', $options);
 
         $result = DB::select("LOWER (\"$field\")")
             ->where("$field", '=', MBSTRING ? mb_strtolower($val) : strtolower($val))
             ->from($table)->execute();
 
+		$object->set_message('unique', 'The field :label must have an unique value.');
+
         if($result->count() > 0)
             return false;
         else
@@ -373,17 +375,17 @@ <h3><a name="methods">Extending Validation class</a></h3>
 $val->add_callable('myvalidation'); // here we add the class to load rules from
 
 $val->add_field('username', 'Your username', 'trim|strip_tags|required|unique[users.username]');</code></pre>
-        
+
         <p>3. Calling callbacks from a model. It works like a method described above, but we only need to call it in other way:</p>
 <pre class="php"><code>$val = Validation::factory();
 $val->add_model('Model_User');</code></pre>
-        
-        <p class="note"> 
-        <strong>Note: </strong> 
+
+        <p class="note">
+        <strong>Note: </strong>
         You need the '_validation_' prefix for a method to be used in validation.
-        </p>     
+        </p>
         </article>
-        
+
         <article>
 			<h3><a name="methods">All methods</a></h3>
 
@@ -400,4 +402,4 @@ <h3><a name="methods">All methods</a></h3>
 	</section>
 
 </body>
-</html>
+</html>

fuel/core/classes/validation.php

@@ -228,7 +228,7 @@ public function run($input = null, $allow_partial = false)
 				foreach ($field->rules as $rule)
 				{
 					$callback	= $rule[0];
-					$params		= $rule[1];
+					$params		= empty($rule[1]) ? array(null) : $rule[1];
 
 					$this->_run_rule($callback, $value, $params, $field);
 				}