I am trying to serialize a class so that it can be saven in Shared Prefences. For serialization I use the JsonSerializable package for Flutter.

My generated code looks like this:

class calculation {
  List<int>? calcs;
  List<int>? results;
  List<int>? selectedSpots;
  List<double>? linedataX;
  List<double>? linedataY;
  Map<int, List<int>>? someMap;



  calculation({
    this.calcs,
    this.results,
    this.selectedSpots,
    this.linedataX,
    this.linedataY,
    this.someMap,

  });




  factory calculation.fromJson(Map<String, dynamic> jsonData) {
    return calculation(
      calcs: jsonData['calcs'].cast<int>(),
      results: jsonData['results'].cast<int>(),
      selectedSpots: jsonData['selectedSpots'].cast<int>(),
      linedataX: jsonData['linedataX'].cast<double>(),
      linedataY: jsonData['linedataY'].cast<double>(),
      someMap: (jsonData['someMap'] as Map?)?.map(
            (k, e) => MapEntry(int.parse(k as String),  e as List<int>  ),
      ),

    );
  }

  static Map<String, dynamic> toMap(calculation calc) => {
        'calcs': calc.calcs,
        'results': calc.results,
        'selectedSpots': calc.selectedSpots,
        'linedataX': calc.linedataX,
        'linedataY': calc.linedataY,
    'someMap': calc.someMap?.map((k, e) => MapEntry(k.toString(), e)),

  }; 

The Error only occurs if my map is Map<int, List>?.

Map<int,int>? works fine.

Any Idea how to correctly cast to list?

CodePudding user response：

Try to change this

calcs: jsonData['calcs'].cast<int>(),
results: jsonData['results'].cast<int>(),
selectedSpots: jsonData['selectedSpots'].cast<int>(),

to this:

calcs: jsonData['calcs'].cast<List<int>>(),
results: jsonData['results'].cast<List<int>>(),
selectedSpots: jsonData['selectedSpots'].cast<List<int>>(),

Now casting to a List

CodePudding user response：

Solved it by using a custom object instead of a map.