Is there any way to dynamically call a static method [duplicate] - flutter

Question

This question already has an answer here:
Calling method on generic type Dart
(1 answer)
Closed 1 year ago.
I want to make APIHelper class.
This class will have method like get, post, put and delete.
And in these method all logic about getting data, decoding, encoding, mapping will be done.
I have base model class like this:
class Model{
Model();
Model.fromJson(Map<String, dynamic> data);
Map<String, dynamic> toJson(){
return {};
}
}
And in API model Event I inherited a class Model:
class EventModel extends Model{
final int desavanjeId;
final String desavanjeName;
EventModel({required this.desavanjeId, required this.desavanjeName});
#override
factory EventModel.fromJson(Map<String, dynamic> data) => EventModel(
desavanjeId: data['desavanjeId'],
desavanjeName: data['desavanjeName'],
);
#override
Map<String, Object> toJson() => {
'desavanjeId': this.desavanjeId,
'desavanjeName': this.desavanjeName,
};
}
And in service I have something like this:
Future<APIResponseModel> get<T>(Uri uri) async{
APIResponseModel apiRespone = APIResponseModel();
try {
Response response = await _client.get(uri);
Map<String, dynamic> data = jsonDecode(response.body);
apiRespone.addData(T.fromJson(data));
} catch (e) {
print(e);
}
return apiRespone;
}
And I am willing to use method get in this way:
get<EventModel>(Uri('...'));
But the problem is that IDE doesn't allow me to use static method fromJson in this way I need.
And I don't want to solve this problem in this way:
switch(Model){
case EventModel:
EventModel.fromJson(data)
}
Is there any other solution for this, but to keep a syntax in this way?

Answer 1

You cannot call a factory constructor or a static method from a generic type in Dart. Your only solution to obtain a similar result would be to use a callback method which will create your object. Here is a possible implementation you could use:
Code Sample
/// By looking at your implementation the Model class should be
/// abstract as it is your base model and should not be able to
/// be instantiated.
abstract class Model {
// fromJson is removed as it will be a static method
Map<String, dynamic> toJson();
}
class EventModel extends Model {
final int desavanjeId;
final String desavanjeName;
EventModel({required this.desavanjeId, required this.desavanjeName});
/// fromJson is now a static method which will return an instance of
/// your constructor so you can still call it like
/// this: EventModel.fromJson()
static EventModel fromJson(Map<String, dynamic> data) => EventModel(
desavanjeId: data['desavanjeId'],
desavanjeName: data['desavanjeName'],
);
#override
Map<String, Object> toJson() => {
'desavanjeId': this.desavanjeId,
'desavanjeName': this.desavanjeName,
};
}
/// Now your method takes a dynamic type which extends your base class Model
/// And you are passing a createCallback parameter which is a Function taking
/// a Map<String, dynamic> as its single parameter and returns an object
/// of type T it will be your method fromJson.
Future<APIResponseModel> get<T extends Model>(
Uri uri, T Function(Map<String, dynamic>) createCallback) async {
APIResponseModel apiRespone = APIResponseModel();
try {
Response response = await _client.get(uri);
final data = jsonDecode(response.body) as Map<String, dynamic>;
apiRespone.addData(createCallback(data));
} catch (e) {
print(e);
}
return apiRespone;
}
Now you should be able to make a call like this:
get<EventModel>(Uri('...'), EventModel.fromJson);
Try the full code on DartPad