validate method
Validates the given value
against the validation rule.
value
: The value to be validated.fields
: A map of form field states for cross-field validation.
Returns true
if the validation passes, false
otherwise.
Implementation
@override
bool validate(T value, Map<String, FormFieldState> fields) {
if (!fields.containsKey(otherField)) {
throw ArgumentError('No field found with name $otherField');
}
return value != fields[otherField]?.value;
}