In Struts 2 we can develop @CustomValidator
which can be used in application widely:
@CustomValidator(type = "CustomerNumberValidator", fieldName = "customerNo")
For validation more than one field we use @ExpressionValidator
:
@ExpressionValidator(expression =
"( (!''.equals(account.firstName) && (!''.equals(account.lastName) )
|| (presonalAccount == false)",
key = "validate.account.name")
If the expression is too complicated and needs to work on more than one field we use OGNL to call the static
method. The static
method will do the validation and return a boolean
for example
@ExpressionValidator(expression = "@foo.bar.CalendarUtil@compareDates(fromDate,toDate)", key = "validate.date.before")
Above is something how a Custom Expression Validator works!
And we use @foo.bar.CalendarUtil@compareDates
in application wide to make this validation for us.
Is there another approach which enables us to use a custom expression validator?!
Is there any custom expression validator which can be added to Struts and we can call it in Action
in the way we use @CustomValidator
?
Create a Custom Validator (not field related):
public final class CompareDatesValidator extends ValidatorSupport {
private String fromDate; // getter and setter
private String toDate; // getter and setter
@Override
public void validate(Object o) throws ValidationException {
Date d1 = (Date)parse(fromDate, Date.class);
Date d2 = (Date)parse(toDate, Date.class);
if (d1==null || d2==null || d2.before(d1)){
addActionError(getDefaultMessage());
}
}
}
Register the custom validator in validators.xml
file:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE validators PUBLIC
"-//OpenSymphony Group//XWork Validator Config 1.0//EN"
"http://www.opensymphony.com/xwork/xwork-validator-config-1.0.dtd">
<validators>
<validator name="compareDatesValidator"
class="org.foo.bar.CompareDatesValidator"/>
</validators>
Use the validator in an action:
private Date startDate; // getter and setter
private Date endDate; // getter and setter
@Validations(
customValidators={
@CustomValidator(type="compareDatesValidator",
message="Dates provided are not valid."
parameters={
@ValidationParameter(name="fromDate", value="${startDate}"),
@ValidationParameter(name="toDate", value="${endDate}")})})
public String execute(){
return SUCCESS;
}