diff --git a/docs/internals/ar.md b/docs/internals/ar.md
new file mode 100644
index 0000000..e69de29
diff --git a/docs/internals/database.md b/docs/internals/database.md
new file mode 100644
index 0000000..e69de29
diff --git a/framework/base/Model.php b/framework/base/Model.php
index 1571ae4..8756b5c 100644
--- a/framework/base/Model.php
+++ b/framework/base/Model.php
@@ -119,7 +119,7 @@ class Model extends Component implements \IteratorAggregate, \ArrayAccess
 	}
 
 	/**
-	 * Returns a list of scenarios and the corresponding relevant attributes.
+	 * Returns a list of scenarios and the corresponding active attributes.
 	 * The returned array should be in the following format:
 	 *
 	 * ~~~
@@ -130,27 +130,14 @@ class Model extends Component implements \IteratorAggregate, \ArrayAccess
 	 * )
 	 * ~~~
 	 *
-	 * Attributes relevant to the current scenario are considered safe and can be
-	 * massively assigned. When [[validate()]] is invoked, these attributes will
-	 * be validated using the rules declared in [[rules()]].
-	 *
 	 * If an attribute should NOT be massively assigned (thus considered unsafe),
 	 * please prefix the attribute with an exclamation character (e.g. '!attribute').
 	 *
-	 * WARNING: The default implementation returns the 'default' scenario and the result of
-	 * [[attributes()]]. This means if the model is in 'default' scenario, all
-	 * public member variables can be massively assigned and will be validated when
-	 * calling [[validate()]]. Make sure you override this method if you do not want
-	 * this behavior (e.g. you only want some of the attributes to be massively assigned
-	 * and validated.)
-	 *
 	 * @return array a list of scenarios and the corresponding relevant attributes.
 	 */
 	public function scenarios()
 	{
-		return array(
-			'default' => $this->attributes(),
-		);
+		return array();
 	}
 
 	/**
@@ -354,8 +341,7 @@ class Model extends Component implements \IteratorAggregate, \ArrayAccess
 	 */
 	public function isAttributeSafe($attribute)
 	{
-		$scenarios = $this->scenarios();
-		return in_array($attribute, $scenarios[$this->getScenario()], true);
+		return in_array($attribute, $this->safeAttributes(), true);
 	}
 
 	/**
@@ -481,22 +467,20 @@ class Model extends Component implements \IteratorAggregate, \ArrayAccess
 	 * @param array $names list of attributes whose value needs to be returned.
 	 * Defaults to null, meaning all attributes listed in [[attributes()]] will be returned.
 	 * If it is an array, only the attributes in the array will be returned.
+	 * @param array $except list of attributes whose value should NOT be returned.
 	 * @return array attribute values (name=>value).
 	 */
-	public function getAttributes($names = null)
+	public function getAttributes($names = null, $except = array())
 	{
 		$values = array();
-
-		if (is_array($names)) {
-			foreach ($this->attributes() as $name) {
-				if (in_array($name, $names, true)) {
-					$values[$name] = $this->$name;
-				}
-			}
-		} else {
-			foreach ($this->attributes() as $name) {
-				$values[$name] = $this->$name;
-			}
+		if ($names === null) {
+			$names = $this->attributes();
+		}
+		foreach ($names as $name) {
+			$values[$name] = $this->$name;
+		}
+		foreach ($except as $name) {
+			unset($values[$name]);
 		}
 
 		return $values;
@@ -567,14 +551,19 @@ class Model extends Component implements \IteratorAggregate, \ArrayAccess
 	 */
 	public function safeAttributes()
 	{
+		$scenario = $this->getScenario();
 		$scenarios = $this->scenarios();
-		$attributes = array();
-		foreach ($scenarios[$this->getScenario()] as $attribute) {
-			if ($attribute[0] !== '!') {
-				$attributes[] = $attribute;
+		if (isset($scenarios[$scenario])) {
+			$attributes = array();
+			foreach ($scenarios[$scenario] as $attribute) {
+				if ($attribute[0] !== '!') {
+					$attributes[] = $attribute;
+				}
 			}
+			return $attributes;
+		} else {
+			return $this->activeAttributes();
 		}
-		return $attributes;
 	}
 
 	/**
@@ -583,11 +572,23 @@ class Model extends Component implements \IteratorAggregate, \ArrayAccess
 	 */
 	public function activeAttributes()
 	{
+		$scenario = $this->getScenario();
 		$scenarios = $this->scenarios();
-		$attributes = $scenarios[$this->getScenario()];
-		foreach ($attributes as $i => $attribute) {
-			if ($attribute[0] === '!') {
-				$attributes[$i] = substr($attribute, 1);
+		if (isset($scenarios[$scenario])) {
+			// scenario declared in scenarios()
+			$attributes = $scenarios[$this->getScenario()];
+			foreach ($attributes as $i => $attribute) {
+				if ($attribute[0] === '!') {
+					$attributes[$i] = substr($attribute, 1);
+				}
+			}
+		} else {
+			// use validators to determine active attributes
+			$attributes = array();
+			foreach ($this->attributes() as $attribute) {
+				if ($this->getActiveValidators($attribue) !== array()) {
+					$attributes[] = $attribute;
+				}
 			}
 		}
 		return $attributes;
diff --git a/framework/db/ar/ActiveRecord.php b/framework/db/ar/ActiveRecord.php
index 3691571..b3b69e4 100644
--- a/framework/db/ar/ActiveRecord.php
+++ b/framework/db/ar/ActiveRecord.php
@@ -44,6 +44,10 @@ use yii\util\StringHelper;
 abstract class ActiveRecord extends Model
 {
 	/**
+	 * @var ActiveRecord[] global model instances indexed by model class names
+	 */
+	private static $_models = array();
+	/**
 	 * @var array attribute values indexed by attribute names
 	 */
 	private $_attributes = array();
@@ -56,6 +60,21 @@ abstract class ActiveRecord extends Model
 	 */
 	private $_related;
 
+
+	/**
+	 * Returns a model instance to support accessing non-static methods such as [[table()]], [[primaryKey()]].
+	 * @return ActiveRecord
+	 */
+	public static function model()
+	{
+		$className = get_called_class();
+		if (isset(self::$_models[$className])) {
+			return self::$_models[$className];
+		} else {
+			return self::$_models[$className] = new static;			
+		}
+	}
+
 	/**
 	 * Returns the metadata for this AR class.
 	 * @param boolean $refresh whether to rebuild the metadata.
@@ -194,7 +213,7 @@ abstract class ActiveRecord extends Model
 	public static function updateAll($attributes, $condition = '', $params = array())
 	{
 		$query = new Query;
-		$query->update(static::tableName(), $attributes, $condition, $params);
+		$query->update(static::model()->tableName(), $attributes, $condition, $params);
 		return $query->createCommand(static::getDbConnection())->execute();
 	}
 
@@ -215,7 +234,7 @@ abstract class ActiveRecord extends Model
 			$counters[$name] = new Expression($value >= 0 ? "$quotedName+$value" : "$quotedName$value");
 		}
 		$query = new Query;
-		$query->update(static::tableName(), $counters, $condition, $params);
+		$query->update(static::model()->tableName(), $counters, $condition, $params);
 		return $query->createCommand($db)->execute();
 	}
 
@@ -229,7 +248,7 @@ abstract class ActiveRecord extends Model
 	public static function deleteAll($condition = '', $params = array())
 	{
 		$query = new Query;
-		$query->delete(static::tableName(), $condition, $params);
+		$query->delete(static::model()->tableName(), $condition, $params);
 		return $query->createCommand(static::getDbConnection())->execute();
 	}
 
@@ -250,9 +269,9 @@ abstract class ActiveRecord extends Model
 	 * You may override this method if the table is not named after this convention.
 	 * @return string the table name
 	 */
-	public static function tableName()
+	public function tableName()
 	{
-		return StringHelper::camel2id(basename(get_called_class()), '_');
+		return StringHelper::camel2id(basename(get_class($this)), '_');
 	}
 
 	/**
@@ -266,7 +285,7 @@ abstract class ActiveRecord extends Model
 	 * If the key is a composite one consisting of several columns, it should
 	 * return the array of the key column names.
 	 */
-	public static function primaryKey()
+	public function primaryKey()
 	{
 	}
 
@@ -633,27 +652,6 @@ abstract class ActiveRecord extends Model
 		$this->_attributes[$name] = $value;
 	}
 
-	/**
-	 * Returns all column attribute values.
-	 * Note, related objects are not returned.
-	 * @param null|array $names names of attributes whose value needs to be returned.
-	 * If this is true (default), then all attribute values will be returned, including
-	 * those that are not loaded from DB (null will be returned for those attributes).
-	 * If this is null, all attributes except those that are not loaded from DB will be returned.
-	 * @return array attribute values indexed by attribute names.
-	 */
-	public function getAttributes($names = null)
-	{
-		if ($names === null) {
-			$names = $this->attributes();
-		}
-		$values = array();
-		foreach ($names as $name) {
-			$values[$name] = isset($this->_attributes[$name]) ? $this->_attributes[$name] : null;
-		}
-		return $values;
-	}
-
 	public function getChangedAttributes($names = null)
 	{
 		if ($names === null) {
diff --git a/framework/db/dao/Query.php b/framework/db/dao/Query.php
index 862154c..0769f92 100644
--- a/framework/db/dao/Query.php
+++ b/framework/db/dao/Query.php
@@ -75,6 +75,7 @@ class Query extends BaseQuery
 			$qb->query = $this;
 			return call_user_func_array(array($qb, $method), $params);
 		} else {
+			/** @var $qb QueryBuilder */
 			return $qb->build($this);
 		}
 	}