flutter text form field validation custom validation error widget code example

Example 1: flutter text field form

TextField(
  decoration: InputDecoration(
    border: InputBorder.none,
    hintText: 'Enter a search term'
  ),
);

Example 2: flutter text form field email validation

String validateEmail(String value) {
    Pattern pattern =
        r"^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]"
        r"{0,253}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]"
        r"{0,253}[a-zA-Z0-9])?)*$";
    RegExp regex = new RegExp(pattern);
    if (!regex.hasMatch(value) || value == null)
      return 'Enter a valid email address';
    else
      return null;
  }