Cannot access decoded json body flutter - flutter

Question

I'm fetching data in flutter and created a helper class as seen below
import 'dart:convert';
import 'package:http/http.dart' as http;
class HttpClient {
final Map<String, String> _headers = {};
void setHeader(String key, String value) {
if (!_headers.containsKey(key)) {
_headers[key] = value;
}
}
Future<http.Response> get(String url) async {
try {
var uri = Uri.parse(url);
var response = await http.get(uri, headers: _headers);
if (response.statusCode == 200) {
dynamic result = jsonDecode(response.body);
return result;
} else {
throw Error();
}
} on Exception catch (_) {
rethrow;
}
}
}
HttpClient appClient = HttpClient();
I call the method from a class as shown below
abstract class AbstractTodoService {
dynamic getTodos() {}
}
class HttpTodoService implements AbstractTodoService {
#override
Future<Response> getTodos() async {
try {
var todos =
await appClient.get('https://jsonplaceholder.typicode.com/todos');
print(todos);
return todos;
} on Exception catch (error) {
print(error);
rethrow;
}
}
}
However, when I print todos or any string in the HttpTodoService after the await call to the HttpClient I do not see anything. However, when I print the result inside the HttpClient I see the response but does not return. When I return a normal string or map everything works normally but when I attempt to use the jsonDecoded response nothing returns.

Answer 1

Your jsonDecode(response.body); returns a List<dynamic> type, but your function return type is Future<http.Response>. This is why you are not getting data.
You can check runtime datatype of a variable by
print(result.runtimeType); // variable_name.runtimeType
Change function return types to Future<List<dynamic>> of get(String url) and getTodos() functions.

Answer 2

It might be because your function returns a future of http.Response which is actually the type of the response after you use http.get. After you use jsonDecode you should get a Map<String, dynamic> which represent the json.
From the documentation:
By looking at the dart:convert documentation, you’ll see that you can decode the JSON by calling the jsonDecode() function, with the JSON string as the method argument.
Map<String, dynamic> user = jsonDecode(jsonString);
print('Howdy, ${user['name']}!');
print('We sent the verification link to ${user['email']}.');
Unfortunately, jsonDecode() returns a Map<String, dynamic>, meaning that you do not know the types of the values until runtime. With this approach, you lose most of the statically typed language features: type safety, autocompletion and most importantly, compile-time exceptions. Your code will become instantly more error-prone.
For example, whenever you access the name or email fields, you could quickly introduce a typo. A typo that the compiler doesn’t know about since the JSON lives in a map structure.
After you use jsonDecode you should turn the map into the object you want to work with using factory fromJson method.
You can read more about is in the documentation https://flutter.dev/docs/development/data-and-backend/json