protected function get_validate_rules() {
		$rules = [];

		foreach ( $this->fields as $key => $field ) {
			// TODO: Group field cannot validate at moment.
			if ( 'group' === $field->get_type() ) {
				continue;
			}

			if ( $rule = $field->get_option( 'validate' ) ) {
				$key           = $field->is_repeatable() ? $key . '.*' : $key;
				$rules[ $key ] = $rule;
			}
		}

		return $rules;
	}