I want to validate my ssn using FilteringTextInputFormatter.allow(RegExp()),

I want it to start with 1 or 2 with 10 length and last 9th numbers any number ,only first one should be 1 or 2

CodePudding user response：

 TextFormField(
            inputFormatters: [
              LengthLimitingTextInputFormatter(10),
              FilteringTextInputFormatter.allow(RegExp(r'^[12][0-9]*$')),
            ],
            decoration: InputDecoration(
              border: InputBorder.none,
              labelText: 'PAN Number',
            ),
          )