Check if date entered is less than 18 years old

Question

I've managed to get the date from 18 years ago today:

var formatter = DateFormat('dd/MM/yyyy');

DateTime today = DateTime.now();
final eighteenY = DateTime(today.year - 18, today.month, today.day);

But now I need to check if the date a user enters is between that date and today's date, and if it is then they are not over the age of 18. How would I go about this? Here is my code:


MaskedTextController _maskDOBController =
MaskedTextController(mask: '00/00/0000');

@override
  Widget build(BuildContext context) {

return Scaffold(

body:

return Row(
mainAxisAlignment: MainAxisAlignment.start,
children: [
  Container(
    height: 48,
    width: 500,
    child: TextFormField(
      controller: _maskDOBController,
      onChanged: (string){
           setState(() {
             provider.dobString = string;
             dobError = false;
             });
           },
        ),
     ),
   ],
 ),
),

Container(height: 80),

Container(
  GestureDetector(
    onTap: (){
      // if the date a user enters in textfield is between that date and today's date
      // print('user is underage');
    }
    child: Text(
     'Continue'
    ),
  ),
);

Does this answer your question? [How to make age validation in flutter](https://stackoverflow.com/questions/61249772/how-to-make-age-validation-in-flutter) — Alex Hartford, May 10 '21 at 19:36
Yes perfect, thanks man. I haven't actually tried your answer out - but the comment linked me to the first answer of that question which worked — James 666, May 10 '21 at 19:46
You're welcome! Most solutions will work, it's all about what syntax tickles your fancy. — Alex Hartford, May 10 '21 at 19:48

score 0 · Answer 1 · answered May 10 '21 at 19:44

This question is a duplicate but I have a solution I use now that I like I felt worth sharing.

You can use an extension to put the function right on DateTime. For example:

extension DateTimeX on DateTime {
  bool isUnderage() =>
      (DateTime(DateTime.now().year, this.month, this.day)
              .isAfter(DateTime.now())
          ? DateTime.now().year - this.year - 1
          : DateTime.now().year - this.year) < 18;
}

void main() {
  final today = DateTime.now();
  final seventeenY = DateTime(today.year - 18, today.month, today.day + 1);
  final eighteenY = DateTime(today.year - 18, today.month, today.day);
  
  print(today.isUnderage());
  print(seventeenY.isUnderage());
  print(eighteenY.isUnderage());
}

It's worth noting this doesn't require intl or any other external package. Paste this right into dartpad.dev to test it out.

You should be careful to use .utc for that, or you might be crossing a DST boundary and that'd mess up the comparisons. — Randal Schwartz, May 11 '21 at 14:30

Check if date entered is less than 18 years old

1 Answers1