CODEWITHSUNDEEP
flutter
doğan kısa
doğan kısa

Reputation: 43

I need to be a nullable parameter in a custom widget

i make a custom widget and using this widget in 7-8 place. i need to add a mask but in widget source said "it cant be null". i dont want to sent null parameter in all usage because i need to use only one place

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

class TextFieldWidget extends StatelessWidget {
final text;
final controller;
final validation;
final mask;
final bool maxLength;
const TextFieldWidget({
  Key? key,
  this.text,
  this.validation,
  this.controller,
  required this.maxLength, this.mask,
}) : super(key: key);

@override
Widget build(BuildContext context) {
  return TextFormField(
    inputFormatters: [
      LengthLimitingTextInputFormatter(maxLength  ? 20 : null),
      mask
    ],
    validator: validation,
    decoration: InputDecoration(
      labelText: text,
      border: OutlineInputBorder(
          borderSide: const BorderSide(color: Colors.grey, width: 0.0),
          borderRadius: BorderRadius.circular(10)),
    ),
  );
}
}

i need to be nullable this "mask" parameter. thanks all!

Upvotes: 0

Views: 57

Answers (1)

esentis
esentis

Reputation: 4666

It's a good practice assigning the types of parameters instead of leaving them dynamic as you do. A simple workaround is below :

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

class TextFieldWidget extends StatelessWidget {
  final text;
  final controller;
  final validation;
  final TextInputFormatter? mask;
  final bool maxLength;
  const TextFieldWidget({
    Key? key,
    this.text,
    this.validation,
    this.controller,
    required this.maxLength,
    this.mask,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return TextFormField(
      inputFormatters: [
        LengthLimitingTextInputFormatter(maxLength ? 20 : null),
        if (mask != null) mask!
      ],
      validator: validation,
      decoration: InputDecoration(
        labelText: text,
        border: OutlineInputBorder(
            borderSide: const BorderSide(color: Colors.grey, width: 0.0),
            borderRadius: BorderRadius.circular(10)),
      ),
    );
  }
}

Upvotes: 3

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