public function getConstrainedKeys($constraint)
	{
		$this->related->select($this->relatedKey);

		return $this->getConstrained($constraint)->fieldsByKey($this->relatedKey);
	}
public function getConstrainedKeys($constraint)
	{
		$this->related->select($this->relatedKey);

		return $this->getConstrained($constraint)->fieldsByKey($this->relatedKey);
	}
public function getConstrainedKeys ( $ constraint ) { $ this -> related -> select ( $ this -> relatedKey ) ; return $ this -> getConstrained ( $ constraint ) -> fieldsByKey ( $ this -> relatedKey ) ; }
Gets keys based on a given constraint

@param   closure  $constraint  The constraint function to apply
@return  array
@since   2.0.0
Gets keys based on a given constraint