This video is about Input Validation and RegExp.

As part of this, I’ll give you an overview of regular expressions (regex) and how they work by using a live web regex validator.

Then we will see how to implement a Regex validator in Dart and integrate it with Flutter’s TextField widget, so that we can validate user input.

I will use a demo app to illustrate two sample use cases:

  • Make a payment (numeric validator with 2 decimal digits, 4 non-decimal digits)
  • Forgot password (email input validation)

Included

  • Demo app preview
  • Regex web examples
  • Regex in Flutter
  • Input Validation Page & TextField
  • TextInputFormatter
  • Email validation
  • Editing / submitting text
  • InputValidationPage implementation
  • keeping focus on the keyboard
  • Wrap up

Notes:

  • I’m using the iOS simulator, but you can open the Android emulator and run the same code.
  • This code was tested with Flutter Beta 0.8.2.

Thanks for watching!