Solving the Flutter OTP View Problem: Automatic Closure of Keyboard and Unfocusing after Filling One Field

Are you tired of dealing with the frustrating issue of the keyboard automatically closing and the OTP fields losing focus after filling just one field in your Flutter app? You’re not alone! This problem has plagued many developers, but fear not, dear reader, for we’ve got the solution right here.

Understanding the Problem

The Flutter OTP view problem arises when the keyboard closes automatically after entering a single digit in an OTP field, making it impossible for the user to enter the remaining digits. This issue is particularly annoying when you have multiple fields for the OTP, and the user is forced to re-open the keyboard multiple times.

Cause of the Problem

The root cause of this issue lies in the way Flutter handles focus nodes and keyboard management. When a TextFormField gains focus, Flutter creates a new focus node, and when the user types a digit and moves to the next field, the previous focus node is lost, causing the keyboard to close.

Solutions to the Flutter OTP View Problem

Now that we understand the problem, let’s dive into the solutions. We’ll explore three approaches to solving this issue:

Solution 1: Using a Single TextFormField with a Custom Input Formatter

This solution involves using a single TextFormField with a custom input formatter to separate the OTP digits.

class OtpInputFormatter extends TextInputFormatter {
  @override
  TextEditingValue formatEditUpdate(
    TextEditingValue oldValue,
    TextEditingValue newValue,
  ) {
    final newText = newValue.text;
    final buffer = StringBuffer();

    for (int i = 0; i < newText.length; i++) {
      buffer.write(newText[i]);
      if ((i + 1) % 4 == 0 && (i + 1) < newText.length) {
        buffer.write(' ');
      }
    }

    return TextEditingValue(
      text: buffer.toString(),
      selection: TextSelection.collapsed(offset: buffer.length),
    );
  }
}

Then, use this formatter in your TextFormField:

TextFormField(
  decoration: InputDecoration(
    border: OutlineInputBorder(),
  ),
  maxLength: 12,
  inputFormatters: [
    OtpInputFormatter(),
    FilteringTextInputFormatter.digitsOnly,
  ],
)

Solution 2: Using Multiple TextFormField with Focus Node Management

This solution involves using multiple TextFormField and managing focus nodes to prevent the keyboard from closing.

Create a list of TextFormField and a list of FocusNode:

final List _otpFields = List.generate(6, (index) => TextFormField());
final List _focusNodes = List.generate(6, (index) => FocusNode());

Then, use the following code to manage focus nodes:

_onEditingComplete(int index) {
  if (index < 5) {
    FocusScope.of(context).requestFocus(_focusNodes[index + 1]);
  }
}

Widget _buildOtpField(int index) {
  return TextFormField(
    focusNode: _focusNodes[index],
    onEditingComplete: () => _onEditingComplete(index),
    decoration: InputDecoration(
      border: OutlineInputBorder(),
    ),
    maxLength: 1,
    keyboardType: TextInputType.number,
    inputFormatters: [
      FilteringTextInputFormatter.digitsOnly,
    ],
  );
}

Finally, use the _buildOtpField function to create your OTP fields:

Row(
  children: [
    _buildOtpField(0),
    _buildOtpField(1),
    _buildOtpField(2),
    _buildOtpField(3),
    _buildOtpField(4),
    _buildOtpField(5),
  ],
)

Solution 3: Using a Third-Party Package – PinInputTextField

If you don’t want to reinvent the wheel, you can use a third-party package like PinInputTextField. This package provides a customizable OTP input field with automatic focus management.

Add the package to your pubspec.yaml file:

dependencies:
  flutter:
    sdk: flutter
  pin_input_text_field: ^2.2.0

Then, use the PinInputTextField widget:

PinInputTextField(
  pinLength: 6,
  autoFocus: true,
  onSubmit: (pin) {
    // handle OTP submission
  },
)

Best Practices for Implementing OTP Views in Flutter

When implementing OTP views in Flutter, keep the following best practices in mind:

• Use a single TextFormField with a custom input formatter for a simple OTP input.

• Use multiple TextFormField with focus node management for a more complex OTP input.

• Consider using a third-party package like PinInputTextField for a hassle-free OTP input implementation.

• Always validate user input to ensure the OTP is correct.

• Provide clear instructions to the user on how to enter the OTP.

• Implement a timeout mechanism to prevent the OTP from being sent multiple times.

Conclusion

The Flutter OTP view problem can be frustrating, but with the solutions and best practices outlined in this article, you should be able to create a seamless OTP input experience for your users. Remember to choose the solution that best fits your app’s requirements, and don’t hesitate to experiment with different approaches until you find the one that works best for you.

Solution	Pros	Cons
Solution 1: Single TextFormField with Custom Input Formatter	Simple to implement, easy to customize	Limited to simple OTP inputs, may not be suitable for complex OTP inputs
Solution 2: Multiple TextFormField with Focus Node Management	Flexible, can be used for complex OTP inputs	More complex to implement, requires focus node management
Solution 3: PinInputTextField Package	Easy to implement, customizable, hassle-free	Dependent on third-party package, may have limitations

By following the instructions and guidelines outlined in this article, you should be able to create a robust and user-friendly OTP input experience in your Flutter app. Happy coding!

Note: The solutions and code snippets provided in this article are for illustrative purposes only and may require modification to fit your specific use case.

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