$checkKeys function Null safety

void $checkKeys(
  1. Map map,
  2. {List<String>? allowedKeys,
  3. List<String>? requiredKeys,
  4. List<String>? disallowNullValues}
)

Helper function used in generated fromJson code when JsonSerializable.disallowUnrecognizedKeys is true for an annotated type or JsonKey.required is true for any annotated fields.

Should not be used directly.

Implementation

void $checkKeys(
  Map map, {
  List<String>? allowedKeys,
  List<String>? requiredKeys,
  List<String>? disallowNullValues,
}) {
  if (allowedKeys != null) {
    final invalidKeys =
        map.keys.cast<String>().where((k) => !allowedKeys.contains(k)).toList();
    if (invalidKeys.isNotEmpty) {
      throw UnrecognizedKeysException(invalidKeys, map, allowedKeys);
    }
  }

  if (requiredKeys != null) {
    final missingKeys =
        requiredKeys.where((k) => !map.keys.contains(k)).toList();
    if (missingKeys.isNotEmpty) {
      throw MissingRequiredKeysException(missingKeys, map);
    }
  }

  if (disallowNullValues != null) {
    final nullValuedKeys = map.entries
        .where(
          (entry) =>
              disallowNullValues.contains(entry.key) && entry.value == null,
        )
        .map((entry) => entry.key as String)
        .toList();

    if (nullValuedKeys.isNotEmpty) {
      throw DisallowedNullValueException(nullValuedKeys, map);
    }
  }
}