how to limit number in textformfield in flutter-CodePudding

Restricts the user's input. For example, if I set the numeric limit to 4000, the user cannot enter a number greater than 4000.

TextFormField(
                //TODO:보유수량 이상 쓰는것 방지할것.
                controller: _recruitStockEditingController,
                keyboardType: TextInputType.number,
                inputFormatters: [FilteringTextInputFormatter.digitsOnly],
                decoration: InputDecoration(
                    contentPadding: EdgeInsets.only(
                        left: 21.0.w, top: 11.0.h, bottom: 11.0.h),
                    hintText: "수량을 입력해주세요.",
                    hintStyle: TextStyle(
                        fontSize: 14.0.sp, color: const Color(0xff696C75)),
                    border: OutlineInputBorder(
                        borderSide: const BorderSide(color: Color(0xffCACBD4)),
                        borderRadius: BorderRadius.circular(6))),
              ),

CodePudding user response：

Try this with TextInputFormatter

import 'package:flutter/services.dart';

 class NumberLimitFormatter extends TextInputFormatter {
   @override
   TextEditingValue formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue) {
     if(newValue.text == "") return newValue;
     if(int.parse(newValue.text.toString())<4000){
       return newValue;
     }
     return oldValue;
   }
 }

Uasge:

TextField(
              controller: myController,
                keyboardType: TextInputType.number,
                inputFormatters: [
                  NumberLimitFormatter(),
                  FilteringTextInputFormatter.digitsOnly,
                 ],
            ),

Using Validator and TextFormField:

 TextFormField(
        keyboardType: TextInputType.number,
        autovalidateMode: AutovalidateMode
            .onUserInteraction, // to instantly valid the input
        inputFormatters: [
          FilteringTextInputFormatter.digitsOnly,
        ],
        validator: (String? value) {
          if (value == null || value.isEmpty)
            return "Enter number";
          else if (int.parse(value) > 4000)
            return "Entered number can't be greater than 4000";
          else
            return null;
        }),

CodePudding user response：

try using a validator.

    validator: (value) {
    if (value > 4000) {
      return "You can't enter a value greater than 4000";
    }
    return null;
  },