queryParameterValidator function

Middleware queryParameterValidator({ required bool required, required String name, required List<String> allowedValues, })

Use queryParameterValidator to verify if query parameter name is allowed you can provide the list of allowed value in allowedValues if the query parameter is mandatory put required at true and else at false

Implementation

Middleware queryParameterValidator(
    {required bool required,
    required String name,
    required List<String> allowedValues}) {
  return (handler) {
    return (request) async {
      if (required) {
        if (!request.url.queryParameters.containsKey(name)) {
          final bodyResponse = BadRequest(
            'about:blank',
            'Required query parameter is missing',
            'The required query parameter \'$name\' is missing',
            400,
            '${request.requestedUri.path}?${request.requestedUri.query}',
            field: name,
          );
          return generateResponse(request, bodyResponse);
        }
      }
      if (request.url.queryParameters.containsKey(name) &&
          !allowedValues.contains(request.url.queryParameters[name])) {
        final bodyResponse = BadRequest(
          'about:blank',
          'Query parameter value not allowed',
          'The value \'${request.url.queryParameters[name]}\' is not allowed, allowed values are: \'${allowedValues.join('\', \'')}\'',
          400,
          '${request.requestedUri.path}?${request.requestedUri.query}',
          field: name,
        );
        return generateResponse(request, bodyResponse);
      }

      return handler(request);
    };
  };
}