public function unique(array $columns, string $message = null)
    {
        $this->initializeUniqueValidator($message);
        $this->unique = $columns;

        return $this;
    }
public function unique(array $columns, string $message = null)
    {
        $this->initializeUniqueValidator($message);
        $this->unique = $columns;

        return $this;
    }
public function unique ( array $ columns , string $ message = null ) { $ this -> initializeUniqueValidator ( $ message ) ; $ this -> unique = $ columns ; return $ this ; }
Columns, that should be unique.

@param array $columns
@param string|null $message

@return static
Columns that should be unique .