call method

@override String? call(String attribute, String value)

Validates whether a value is numeric.

This method checks if the input value can be parsed as a numeric value. If the value is not numeric, an error message is generated using the buildMessage method.

Parameters:

• attribute: The identifier of the form attribute being validated.
• value: The value to be validated.

Returns: A validation error message if the value is not a numeric value, or null if the value is a valid numeric value.

Implementation

@override
String? call(String attribute, String value) {
  if (value.isNotEmpty) {
    final parsedValue = num.tryParse(value);
    if (parsedValue == null) {
      return buildMessage(attribute, value);
    }
  }
  return null;
}