validate function
Implementation
String? validate(FormControls element, String value) {
var val = value.trim();
var validationMessages = <String?>[];
if (element.controlConfig.isRequired && isRequired(val) != null) {
validationMessages.add(isRequired(val));
}
if (element.controlConfig.inputType != null &&
element.controlConfig.inputType == TextInputType.emailAddress &&
isEmailValid(val)) {
validationMessages.add(emailValidationMessage(val));
}
if (element.controlConfig.validator != null) {
validationMessages.add(element.controlConfig.validator!());
}
if (element.controlConfig.alreadyExists != null &&
element.controlConfig.alreadyExists.contains(val.toLowerCase())) {
validationMessages
.add(alreadyExists(val, element.controlConfig.label!.toLowerCase()));
}
return validationMessages.isNotEmpty ? validationMessages.join(' ') : null;
}