Programming
Cross field validation with Bean Validation
Bean Validation provides a quite flexible API for writing your own validators, allowing cross field validation.
See the example below, where the ZIP code is validated according to the country code:
@ValidAddress
public class Address {
@NotNull
@Size(max = 50)
private String street1;
@Size(max = 50)
private String street2;
@NotNull
@Size(max = 10)
private String zipCode;
@NotNull
@Size(max = 20)
private String city;
@Valid
@NotNull
private Country country;
// Getters and setters
}
public class Country {
@NotNull
@Size(min = 2, max = 2)
private String iso2;
// Getters and setters
}
@Documented
@Target(TYPE)
@Retention(RUNTIME)
@Constraint(validatedBy = { MultiCountryAddressValidator.class })
public @interface ValidAddress {
String message() default "{com.example.validation.ValidAddress.message}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
public class MultiCountryAddressValidator
implements ConstraintValidator<ValidAddress, Address> {
public void initialize(ValidateAddress constraintAnnotation) {
}
@Override
public boolean isValid(Address address,
ConstraintValidatorContext constraintValidatorContext) {
Country country = address.getCountry();
if (country == null || country.getIso2() == null || address.getZipCode() == null) {
return true;
}
switch (country.getIso2()) {
case "FR":
return // Check if address.getZipCode() is valid for France
case "GR":
return // Check if address.getZipCode() is valid for Greece
default:
return true;
}
}
}