code: public function fetchByAlias($strTable, $strAlias, $varValue)
  	{
  		if (isset($this->arrAliases[$strTable][$strAlias][$varValue]))
  		{
  			$strPk = $this->arrAliases[$strTable][$strAlias][$varValue];
  
  			if (isset($this->arrRegistry[$strTable][$strPk]))
  			{
  				return $this->arrRegistry[$strTable][$strPk];
  			}
  		}
  
  		return null;
  	}
docs: Fetch a model by one of its aliases
  
  @param string $strTable The table name
  @param string $strAlias The alias
  @param mixed  $varValue The alias value
  
  @return Model|null The model or null