如何在Flutter的TextField中添加遮罩？ [英] How to add a mask in a TextField in Flutter?

问题描述

由于我不喜欢日期选择器，所以我试图将日期掩码添加到textField，因为例如对于出生日期，它并不那么灵活。
之后，从字符串转换为日期时间，我相信我可以继续进行该项目，
预先感谢。

I'm trying to add a date mask to a textField since I did not like the Date Picker because for date of birth, for example, it is not as nimble. After that, converting from string to datetime, I believe I can continue the project, Thanks in advance.

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; 
}

推荐答案

我修改了一些内容并进行了管理以获得预期的结果。

I modified some things and managed to get the expected result.

我创建了此类来定义变量

I created this class to define the variable

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输入格式

And finally I added an inputformat to the textfield

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,
              ]
        ),

现在可以了，谢谢

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