Show hint text in text field even if text field contains only spaces-CodePudding

How can I display a hint text in a TextField if it contains only space characters like ' '?

const TextField(
  decoration: InputDecoration(
    hintText: 'a hint text'
  ),
),

In this code example the hint text is only displayed if the content of the TextField is empty.

I need this because I need to detect when the user press the backspace button on an empty TextField. Read more here: https://medium.com/super-declarative/why-you-cant-detect-a-delete-action-in-an-empty-flutter-text-field-3cf53e47b631

CodePudding user response：

After diving deeper into the problem I found a solution with InputDecorator:

const InputDecorator(
  isEmpty: true, // if true, the hint text is shown
  decoration: InputDecoration(
    hintText: 'a hint text'
  ),
  child: TextField(),
),

So my solution is this:

String _value = ''; // state variable
...

InputDecorator(
  isEmpty: _value.trim().isEmpty, // override the default isEmpty behavior
  decoration: const InputDecoration(
    hintText: 'a hint text',
  ),
  child: TextField(
    onChanged: (v) => setState(() => _value = v),
  ),
),

CodePudding user response：

Probably, you should use decoration property of your TextField. Something like that:

SizedBox(
        height: 50,
        width: 100,
        child: TextField(
            decoration: InputDecoration(
              border: OutlineInputBorder(),
              label: Text('Your stable hint')
            ),
        )
      ),