The method '[]' can't be unconditionally invoked because the receiver can be 'nu-CodePudding

I want to call the data from API using horizontal_data_table on flutter. this is the code where it gets the error

       Container(
          width: 200,
          height: 52,
          padding: const EdgeInsets.fromLTRB(5, 0, 0, 0),
          alignment: Alignment.centerLeft,
          child: Text(widget.leavelistmodel.response[index].paidLeaveEmployeeNip),
        ),

and the data model from the result looks like this:

class LeaveListResult {
  int? paidLeaveId;
  String? paidLeaveEmployeeNip;
  String? paidLeaveEmployeeFullName;
}

I'm already changing it into? and ! it still got an error, how can I fix the error?

CodePudding user response：

We used nullSafty for the model variable. ?

class LeaveListResult {
  int? paidLeaveId;
  String? paidLeaveEmployeeNip;
  String? paidLeaveEmployeeFullName;
}

Since it is the same as Swift's optional, nullSafty must be canceled.

Container(
          width: 200,
          height: 52,
          padding: const EdgeInsets.fromLTRB(5, 0, 0, 0),
          alignment: Alignment.centerLeft,
          child: Text(widget.leavelistmodel.response[index].paidLeaveEmployeeNip ?? 'NULL'),
        ),

You can force unwrapping with !, but this is not a good practice. The reason is that an error occurs when it is null. When it is null by using channing, an exception handling message should be displayed instead of an error.

CodePudding user response：

the Text can't accept a nullable String?, if you're sure that your data isn't null then do this:

  child: Text(widget.leavelistmodel!.response[index]!.paidLeaveEmployeeNip),

you can also set a default value for the String? that will be shown when it's null :

  child: Text(widget.leavelistmodel?.response[index]?.paidLeaveEmployeeNip ?? "default value"),

CodePudding user response：

The response can be null on this case. You can check the null value and then move forward. As for paidLeaveEmployeeNip filed also a nullable String but Text widget doesnt accept null value. You can directly accept null string

 child: Text("${widget.leavelistmodel.response?[index].paidLeaveEmployeeNip}"),

Or for default value

Text(widget.leavelistmodel.response?[index].paidLeaveEmployeeNip ?? "Got Null")