messageFromJson function

Map<String, Object?> messageFromJson(Object? json, List<Map<String, Object?>> descriptor, { List<Map<String, Object?>>? anyTypeResolver(String typeName)?, })

Converts a proto3-JSON value json (a decoded Map/List/scalar, NOT a serialized string) into a decoded message map (snake_case proto field names).

This is the object-valued sibling of unmarshalJson (unmarshalJson first jsonDecodes its string, then calls this). Generated model code delegates its fromProto3Json() here.

See messageToJson for the per-call anyTypeResolver threading (no global mutation; falls back to the library-global hook when omitted).

Implementation

Map<String, Object?> messageFromJson(
  Object? json,
  List<Map<String, Object?>> descriptor, {
  List<Map<String, Object?>>? Function(String typeName)? anyTypeResolver,
}) {
  if (json is! Map) {
    throw FormatException(
      'Expected a JSON object at top level, got ${json.runtimeType}',
    );
  }
  final stringMap = <String, Object?>{};
  for (final entry in json.entries) {
    stringMap[entry.key.toString()] = entry.value;
  }
  return _unmarshalFromMap(stringMap, descriptor, anyTypeResolver);
}