Flutter JsonSerialization

Question

I am currently building an app where the user is able to store List items as favorites on their device. Debugging my app I am running in the following error:

Exception has occurred.
_CastError (type 'Null' is not a subtype of type 'Widget' in type cast)

This is my code:

LogEntry _$LogEntryFromJson(Map<String, dynamic> json) {
  return LogEntry(
      mechanismId: json['mechanismId'] as int?,
      timestamp: DateTime.parse(json['timestamp'] as String),
      navigation: json['navigation'] as Widget);
}

Map<String, dynamic> _$LogEntryToJson(LogEntry instance) => <String, dynamic>{
      'mechanismId': instance.mechanismId,
      'timestamp': instance.timestamp.toIso8601String(),
      'navigation:': instance.navigation,
    };

The mechanismID is the respective ID of a List item and the navigation stands for the route of the detail page.

'json['navigation'] ' is returning null, change cast to 'as Widget?' or make sure 'json['navigation'] ' cannot be null. — Artur Sikora
– Artur Sikora, Commented May 2, 2022 at 19:37

Mark Rotteveel · Accepted Answer · 2022-05-04 10:20:04Z

0

LogEntry _$LogEntryFromJson(Map<String, dynamic> json) {
  return LogEntry(
      mechanismId: json['mechanismId'] as int?,
      timestamp: DateTime.parse(json['timestamp'] as String),
      navigation: json['navigation'] as Widget?);
}

edited May 4, 2022 at 10:20

Mark Rotteveel

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answered May 3, 2022 at 17:02

Nick

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1 Comment

Mark Rotteveel Over a year ago

Please don't post only code as answer, but also provide an explanation what your code does and how it solves the problem of the question. Answers with an explanation are usually more helpful and of better quality, and are more likely to attract upvotes.

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