CODEWITHSUNDEEP
flutter
Farzad Jafari
Farzad Jafari

Reputation: 73

TextField's text does not update after changing its controller's text in onChanged field

I have a textfield with a controller. What I want to do is change the input characters as they are being received. But what happens is that it replaces the first entered character, but then, the controller's text does not update on changes afterwards. Actually, nothing happens when you press a key.

here is my textfield:

TextEditingController amountController = TextEditingController();
TextField(
  controller: amountController,
  onChanged: (value) {
  amountController.text = replaceFarsiNumber(value);
  },
)

Here is the replaceFarsiNumber() function for further information:

String replaceFarsiNumber(String input) {
  const english = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9'];
  const farsi = ['۰', '۱', '۲', '۳', '۴', '۵', '۶', '۷', '۸', '۹'];
  for (int i = 0; i < english.length; i++) {
    input = input.replaceAll(english[i], farsi[i]);
  }
  return input;
}

Upvotes: 2

Views: 3413

Answers (3)

Farzad Jafari
Farzad Jafari

Reputation: 73

After a lot of struggle, I figured out that when we change the amountController.text, the cursor moves to the beginning of the text, and therefore, you can't edit the textField's value nor it updates on changes. So, you had to reposition the cursor to the end of string manually:

    onChanged: (value) {
      controller1.text = replaceFarsiNumber(value);
      //reposition the cursor to the end of string
      controller1.selection =
          TextSelection.fromPosition(
              TextPosition(offset: value.length));
    },

Upvotes: 2

aedemirsen
aedemirsen

Reputation: 142

your code seems correct, to double check I tried your code and it runs correctly. Here is the output:

enter image description here

There may be another reason of your problem...

Upvotes: 1

Ivo
Ivo

Reputation: 23164

I believe the problem is that it enters an infinite loop. onChanged changes the text which in turn triggers a new onChanged and this goes on infinitely. It might help to only assign to the text when the text is different. So like

onChanged: (value) {
  var newValue = replaceFarsiNumber(value);
  if (value != newValue) {
    amountController.text = newValue;
  }
},

Upvotes: 0

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