Flutter Unhandled Exception: type 'Null' is not a subtype of type 'List<dynamic>' in type cast

Question

I need to assign a model to a list in the application, but I am getting the error I mentioned in the title.

Although I get this error on the android side, I do not have a problem, but when I try it on the ios side, my application crashes.

List<MessageModel> messageList = [];
String? message;
bool success = false;

@override
MessageService decode(dynamic data) {
messageList = (data as List).map((e) => MessageModel.fromJsonData(e)).toList(); ----> Unhandled Exception: type 'Null' is not a subtype of type 'List<dynamic>' in type cast
return this;
}

聂超群 · Accepted Answer · 2021-12-08 07:07:01Z

1

The reason you get the error is data is null.

Try my solution:

List<MessageModel> messageList = [];
String? message;
bool success = false;

@override
MessageService decode(dynamic data) {
  messageList = data?.map((e) => MessageModel.fromJsonData(e))?.toList() ?? [];
  return this;
}

answered Dec 8, 2021 at 7:07

聂超群

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2 Comments

Kutluhan Özbakan Over a year ago

now my list doesnt get anymore and get [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: type '_TypeError' is not a subtype of type 'DioError' in type cast errors

聂超群 Over a year ago

what is your data's type?

Dharman · Accepted Answer · 2022-09-22 21:47:59Z

1

You can declare it as nullable:

List<MessageModel> ?messageList = [];

edited Sep 22, 2022 at 21:47

Dharman♦

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answered Dec 8, 2021 at 6:58

Anmol Mishra

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