public function getConstraint($fieldName, $constraintName)
    {
        if (isset($this->constraints[$fieldName][$constraintName])) {
            return $this->constraints[$fieldName][$constraintName];
        }
    }
public function getConstraint($fieldName, $constraintName)
    {
        if (isset($this->constraints[$fieldName][$constraintName])) {
            return $this->constraints[$fieldName][$constraintName];
        }
    }
public function getConstraint ( $ fieldName , $ constraintName ) { if ( isset ( $ this -> constraints [ $ fieldName ] [ $ constraintName ] ) ) { return $ this -> constraints [ $ fieldName ] [ $ constraintName ] ; } }
get a constraint by fieldName, constraintName
@param string $fieldName
@param string $constraintName
@return ZenValidatorConstraint
get a constraint by fieldName constraintName