Flutter Question posted in
The official Flutter documentation can be found here.

bad state error while fetching record from a list using first in flutter

I Have a list that contains some details based on date, like daysummarymodel.

in my app tapping on any date..it should show its summary and that i am using following code

final daySummeryModel=daySummeryList.where((element) => element.dateTime.isSameDate(date)).toList().first;

its working fine but if there is no summary of given date..its showing error like bad state

how to return null if no summary found..so that i can check later if its null nothing to do

class DaySummeryModel
{
  DateTime dateTime;
  int entries;
  double expenseTotal;
  double incomeTotal;

  DaySummeryModel({required this.dateTime,required this.expenseTotal,required this.incomeTotal,required this.entries});

  double get balance=>incomeTotal-expenseTotal;
}
Tags:

2

Answers


  1. 0

    The issue occurs because .first throws an error when the list is empty. Here are a few ways to solve this:

    Using firstOrNull (Recommended for Dart 2.12+):

    final daySummeryModel = daySummeryList
.where((element) => element.dateTime.isSameDate(date))
.firstOrNull;

    If you’re using an older version of Dart or prefer more explicit control, you can use a different approach:

    final filteredList = daySummeryList
.where((element) => element.dateTime.isSameDate(date))
.toList(); 
final daySummeryModel = filteredList.isNotEmpty ? filteredList.first : null;
    Login or Signup to reply.
  2. 0

    Please check the list daySummeryList before take first from list :

    final daySummeryModel = daySummeryList.where((element) => element.dateTime.isSameDate(date)).toList();

DaySummeryModel? summary;
if (daySummeryModel.isNotEmpty) {
  summary = daySummeryModel.first;
} else {
  summary = null;
}
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search