I want to convert JSON data to a generic type in Flutter

Question

Hello everyone I'm new to Flutter. I want to convert JSON data to a generic type in Flutter.

class ServiceResult<T>
{
  T result;
  String message;
  bool hasError;
  bool hasSuccessMessage;
}

I can use Map<string, dynamic> But I don't want to use it dynamically. I want to cast to T. I have always seen dynamic uses in my research. Is there a method that I can cast directly to T?

Answer 1

You can't really avoid using Map<string, dynamic>. Because that's the only way you map a JSON into a class object, but if you prefer to Convert a JSON into a T class here is the example. first, create ServiceResult as you do Then create T class for the result

class ServiceResult
{
  T result;
  String message;
  bool hasError;
  bool hasSuccessMessage;
}
class T{
  String yourStringHere;
  String yourAnotherStringHere;
  int yourIntHere;
}

crucial part

ServiceResult.fromJson(Map<String, dynamic> json) {
    message= json['message'];
    hasError= json['has_error'];
    hasSuccessMessage= json['has_success_message'];
    result = json['result'] != null ? new result .fromJson(json['result']) : null;
}
T.fromJson(Map<String, dynamic> json) {
    yourStringHere= json['your_string_here'];
    yourAnotherStringHere= json['your_another_string_here'];
    yourIntHere= json['your_int_here'];
}

bonus: Javier Lecuona create genius tools to convert a JSON into a class object, so you can be lazy like I do :P here: https://javiercbk.github.io/json_to_dart/