如何在Flutter的TextField中添加蒙版？

Question

我正在尝试向textField添加日期掩码，因为我不喜欢日期选择器，因为对于出生日期，它不是那么敏捷。之后，从字符串转换为日期时间，我相信我可以继续该项目，提前谢谢。

static final TextEditingController _birthDate = new TextEditingController();
    new TextFormField( 
            controller: _birthDate, 
            maxLength: 10,
            keyboardType: TextInputType.datetime, 
            validator: _validateDate
        ), String _validateDate(String value) { 
    if(value.isEmpty)
        return null;
    if(value.length != 10)
        return 'Enter date in DD / MM / YYYY format';
    return null; 
}

Answer 1

我修改了一些东西，并设法得到预期的结果。

我创建了这个类来定义变量

static final _UsNumberTextInputFormatter _birthDate = new _UsNumberTextInputFormatter();

class _UsNumberTextInputFormatter extends TextInputFormatter {
  @override
  TextEditingValue formatEditUpdate(
TextEditingValue oldValue,
TextEditingValue newValue  ) {
final int newTextLength = newValue.text.length;
int selectionIndex = newValue.selection.end;
int usedSubstringIndex = 0;
final StringBuffer newText = new StringBuffer();
if (newTextLength >= 3) {
  newText.write(newValue.text.substring(0, usedSubstringIndex = 2) + '/');
  if (newValue.selection.end >= 2)
    selectionIndex ++;
}
if (newTextLength >= 5) {
  newText.write(newValue.text.substring(2, usedSubstringIndex = 4) + '/');
  if (newValue.selection.end >= 4)
    selectionIndex++;
}
if (newTextLength >= 9) {
  newText.write(newValue.text.substring(4, usedSubstringIndex = 8));
  if (newValue.selection.end >= 8)
    selectionIndex++;
}
// Dump the rest.
if (newTextLength >= usedSubstringIndex)
  newText.write(newValue.text.substring(usedSubstringIndex));
return new TextEditingValue(
  text: newText.toString(),
  selection: new TextSelection.collapsed(offset: selectionIndex),
); 
} 
}

最后我在文本字段中添加了一个inputformat

new TextFormField( 
          maxLength: 10,
          keyboardType: TextInputType.datetime, 
          validator: _validateDate,
          decoration: const InputDecoration(
            hintText: 'Digite sua data de nascimento',
            labelText: 'Data de Nascimento',
          ),
          inputFormatters: <TextInputFormatter> [
                WhitelistingTextInputFormatter.digitsOnly,
                // Fit the validating format.
                _birthDate,
              ]
        ),

现在没事了，谢谢

Answer 2

https://pub.dartlang.org/packages/masked_text

masked_text

一个掩盖文本的包，所以如果你想要一个电话面具，或邮政编码或任何类型的面具，只需使用它：D

入门

它非常简单，就像其他所有的Widget一样。

new MaskedTextField
(
    maskedTextFieldController: _textCPFController,
    mask: "xx/xx/xxxx",
    maxLength: 10,
    keyboardType: TextInputType.number,
    inputDecoration: new InputDecoration(
    hintText: "Digite a data do seu nascimento", labelText: "Data"),
);

'x'是您的文本将具有的普通字符。

这个样本最终再现了这样的东西：11/02/1995。

Answer 3

此解决方案检查日期是否超出范围（例如，没有像13这样的月份）。这是非常低效的，但它的工作原理。

---

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

class DateFormatter extends TextInputFormatter {
  final String mask = 'xx-xx-xxxx';
  final String separator = '-';

  @override
  TextEditingValue formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue) {
 if(newValue.text.length > 0) {
  if(newValue.text.length > oldValue.text.length) {
    String lastEnteredChar = newValue.text.substring(newValue.text.length-1);
    if(!_isNumeric(lastEnteredChar)) return oldValue;

    if(newValue.text.length > mask.length) return oldValue;
    if(newValue.text.length < mask.length && mask[newValue.text.length - 1] == separator) {

      String value = _validateValue(oldValue.text);
      print(value);

      return TextEditingValue(
        text: '$value$separator$lastEnteredChar',
        selection: TextSelection.collapsed(
          offset: newValue.selection.end + 1,
        ),
      );
    }

    if(newValue.text.length == mask.length) {
      return TextEditingValue(
        text: '${_validateValue(newValue.text)}',
        selection: TextSelection.collapsed(
          offset: newValue.selection.end,
        ),
      );
    }
  }
}
return newValue;
}

bool _isNumeric(String s) {
if(s == null) return false;
return double.parse(s, (e) => null) != null;
}

 String _validateValue(String s) {
String result = s;

if (s.length < 4) { // days
  int num = int.parse(s.substring(s.length-2));
  String raw = s.substring(0, s.length-2);
  if (num == 0) {
    result = raw + '01';
  } else if (num > 31) {
    result = raw + '31';
  } else {
    result = s;
  }
} else if (s.length < 7) { // month
  int num = int.parse(s.substring(s.length-2));
  String raw  = s.substring(0, s.length-2);
  if (num == 0) {
    result = raw + '01';
  } else if (num > 12) {
    result = raw + '12';
  } else {
    result = s;
  }
} else { // year
  int num = int.parse(s.substring(s.length-4));
  String raw  = s.substring(0, s.length-4);
  if (num < 1950) {
    result = raw + '1950';
  } else if (num > 2006) {
    result = raw + '2006';
  } else {
    result = s;
  }
}

print(result);
return result;
}

}