How do I return error from a Future in dart?
In my flutter app, I have a future that handles http requests and returns the decoded data. But I want to be able to send an error if the status code != 200
that can be gotten with the .catchError()
handler.
Heres the future:
Future<List> getEvents(String customerID) async {
var response = await http.get(
Uri.encodeFull(...)
);
if (response.statusCode == 200){
return jsonDecode(response.body);
}else{
// I want to return error here
}
}
and when I call this function, I want to be able to get the error like:
getEvents(customerID)
.then(
...
).catchError(
(error) => print(error)
);
Throwing an error/exception:
You can use either return
or throw
to throw an error or an exception.
-
Using
return
:Future<void> foo() async { if (someCondition) { return Future.error('FooError'); } }
-
Using
throw
:Future<void> bar() async { if (someCondition) { throw Exception('BarException'); } }
Catching the error/exception:
You can use either catchError
or try-catch
block to catch the error or the exception.
-
Using
catchError
:foo().catchError(print);
-
Using
try-catch
:try { await bar(); } catch (e) { print(e); }
You can use throw
:
Future<List> getEvents(String customerID) async {
var response = await http.get(
Uri.encodeFull(...)
);
if (response.statusCode == 200){
return jsonDecode(response.body);
}else{
// I want to return error here
throw("some arbitrary error"); // error thrown
}
}