Flutter error type 'List<Object?>' is not a subtype of type 'List<String>-CodePudding

I have this list:

List<dynamic> activityDays = [];

And this code:

  getItems(AsyncSnapshot<QuerySnapshot> snapshot) {
    if (widget.user.uid.isNotEmpty) {
      // ignore: missing_return
      snapshot.data.documents.map<Column>((f) {
        if (f.documentID == widget.currentList.keys.elementAt(widget.i)) {
          f.data.forEach((a, b) {
            if (a == "activities") {
              List<dynamic> markMap = f.data['activities'];
              for (var element in markMap) {
                activityDays.add(element['days']);
              }
            }
          });
        }
      }).toList();

And printing the list gives the result: [[M, T, L], [T, T, L]]

But when I am trying to get an item from the list it gives me error: type 'List' is not a subtype of type 'List'

I am using it like this:

GroupedCheckbox(
                                                            itemList:
                                                                activityDays
                                                                    .elementAt(
                                                                        i),
                                                            checkedItemList:
                                                                checkedItemList,
                                                            onChanged:
                                                                (itemList) {
                                                              setState(() {
                                                                // selectedItemList = itemList;
                                                                print(
                                                                    'SELECTED ITEM LIST $itemList');
                                                              });
                                                            },
                                                            orientation:
                                                                CheckboxOrientation
                                                                    .VERTICAL,
                                                            checkColor:
                                                                Colors.blue,
                                                            activeColor:
                                                                Colors.red),

What am I doing wrong?

CodePudding user response：

Did you tried just declaring your lists as List<String> to avoid variable type conflict?

CodePudding user response：

Instead of defining data type as List<dynamic> you can define it as List<List<String>> or what ever type you are getting for f.data['activities']. If not do type case list as List<DATA_TYPE>

CodePudding user response：

List<String> activityDays = []; // Change to String

try like that

getItems(AsyncSnapshot<QuerySnapshot> snapshot) {
    if (widget.user.uid.isNotEmpty) {
      // ignore: missing_return
      snapshot.data.documents.map<Column>((f) {
        if (f.documentID == widget.currentList.keys.elementAt(widget.i)) {
          f.data.forEach((a, b) {
            if (a == "activities") {
              List<dynamic> markMap = f.data['activities'];
              for (var element in markMap) {
                activityDays.add(element['days'].toString()); // assign as String
              }
            }
          });
        }
      }).toList();