[SOLVED] Null is not a subtype

I have 10 attributes in my collection and when I run the application it gives an error at this point:

TypeScript

    databases ?? init();
    try {
      String userId = await AuthHelper.instance.getUserId() ?? "";
      DocumentList response = await databases!.listDocuments(
        databaseId: "64046c8b50eba8c807d0",
        collectionId: "6405162fd68c7c61df67",
      );
      return response.documents
          .map(
            (e) => TodoModel.fromJson(e.data, e.$id,)
          )
          .toList();
    } catch (e) {
      rethrow;
    }
  }```

Exception has occurred.
_TypeError (type 'Null' is not a subtype of type 'String')

This is what my data model looks like:

class TodoModel { String name; int scores; double progress; List<dynamic> errors; List<dynamic> friends; int alchiki; String refcode; DateTime createdAt; String id; String userId;

TodoModel({ required this.name, required this.scores, required this.progress, required this.errors, required this.friends, required this.alchiki, required this.refcode, required this.createdAt, required this.userId, required this.id, });

TodoModel.fromJson(Map<String, dynamic> json, String tempId) : name = json['first_name'], scores = json['scores'], progress = json['progress'], errors = json['errors'], friends = json['friends'], alchiki = json['alchiki'], refcode = json['refcode'], createdAt = DateTime.parse(json['createdAt']), userId = json['userId'], id = tempId;

Map<String, dynamic> toJson() => { 'first_name': name, 'scores': scores, 'progress': progress, 'errors': errors, 'friends': friends, 'alchiki': alchiki, 'refcode': refcode, 'createdAt': createdAt.toIso8601String(), 'userId': userId, }; } ```

TL;DR

It seems like there's an issue with the `refcode` attribute being null in your data model. One solution is to remove the `refcode` attribute from the model, which should make the application work fine. If you want to keep the `refcode` attribute, make sure to handle null values properly in your code. You can modify the `fromJson` method in your data model as follows: ``` TodoModel.fromJson(Map<String, dynamic> json, String tempId) : name = json['first_name'] ?? "", scores = json['scores'], progress = json['progress'], errors = json['

If I remove the "refcode" attribute from the model, then the application will work fine.