import 'package:backend_dart/domain/errors/app_error.dart'; import 'package:fpdart/fpdart.dart'; TaskEither> Function(Map) validateJsonKeys(List requiredKeys) { return (json) { final missingKeys = requiredKeys.where((key) => !json.containsKey(key)).toList(); if (missingKeys.isNotEmpty) { return TaskEither.left(AppError.validationError( message: 'Missing required keys: ${missingKeys.join(', ')}', )); } return TaskEither.right(json); }; }