Feature for deserializing Generic Classes was introduced to freeze a few months back.
I am trying to follow the documentation, but I am facing a compile time error:
The argument type 'NameOfClass Function(Map<String, dynamic>)' can't be assigned to the parameter type 'NameOfClass Function(Object?)'.
Here is a simplified version of my data classes to explain what I am trying to achieve.
1. Outer Class
@Freezed(genericArgumentFactories: true)
class ResponseWrapper<T> with _$ResponseWrapper<T>{
const factory ResponseWrapper ({
final String? Status,
final T? Response,
}) = _ResponseWrapper;
factory ResponseWrapper.fromJson(Map<String, dynamic> json,
T Function(Object? json) fromJsonT)
=> _$ResponseWrapperFromJson<T>(json, fromJsonT);
}
2. Inner Class
@freezed
class NewUser with _$NewUser {
const factory NewUser({
String? firstName,
String? middleName,
String? surname,
String? username,
String? emailId,
}) = _NewUser;
factory NewUser.fromJson(Map<String, dynamic> json) =>
_$NewUserFromJson(json);
}
Running the command flutter pub run build_runner build runs without any errors and all the red squiggly lines disappear.
3. Attempting to deserialize
I am using the following code to deserialize the json.
const String stringResponse = '{"Status": "Success", "Response": { "firstName": "XYZ", "middleName": "ABC", "surname": "EDF", "username": "abc", "emailId": "[email protected]" } }';
final Map<String, dynamic> encoded = jsonDecode(stringResponse);
final ResponseWrapper<NewUser> newUserWithWrapper = ResponseWrapper.fromJson(encoded, NewUser.fromJson);
In the above code block, on the last line's NewUser.fromJson I am getting red squiggly line error that says:
The argument type 'NewUser Function(Map<String, dynamic>)' can't be assigned to the parameter type 'NewUser Function(Object?)'.