How to put a path param to the request body before validation happens? - jax-rs

Question

I got the following test entity:
public class Test {
public String id;
public String name;
}
My test resource looks like this:
#Path("test")
#Consumes(MediaType.APPLICATION_JSON)
#Produces(MediaType.APPLICATION_JSON)
public class TestResource {
#Path("{id}")
#POST
public Test test(#Valid Test test){
return test;
}
}
If I do a POST with name as request body, I will end up with an entity which has a name but no id set. If I want to have set the id, I define a #PathParam("id") String id and then set the id with test.id = id. That is what I am using right now.
In this case, if I put a #NotNull constraint to the ID, the validation fails.
How can I 'put' the parsed ID to the request body, before the validation is happening? Ideal, not manually in any case.

Answer 1

You should remove the #NotNull annotation and ensure that no ID is given from the POST request. And in your GET endpoints ensure that the field is not null, probably with an own annotation. I did this with my own annotation #TestIdNull(false).
In your code you would place the annotation like this:
#Path("{id}")
#POST
public Test test(#TestIdNull(true) Test test){
return test;
}
while the annotation interface looks quite simple:
#Target({ElementType.PARAMETER,ElementType.TYPE_USE})
#Retention(RetentionPolicy.RUNTIME)
#Documented
#Constraint(validatedBy = PetIdNullValidator.class)
public #interface TestIdNull {
String message() default "Post request. ID value forbidden.";
boolean value() default true;
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
and the implementation would be
#Provider
#NoArgsConstructor
public class TestIdNullValidator implements ConstraintValidator<TestIdNull, Test> {
private boolean switchNullCheck;
/**
* {#inheritDoc}
*/
#Override
public void initialize(final TestIdNull constraintAnnotation) {
switchNullCheck = constraintAnnotation.value();
}
/**
* {#inheritDoc}
*/
#Override
public boolean isValid(final Test test, final ConstraintValidatorContext context) {
if (null == test) {
return true;
}
context.disableDefaultConstraintViolation();
context.buildConstraintViolationWithTemplate("ENTER YOUR MESSAGE HERE").addConstraintViolation();
return switchNullCheck ? test.id() == null : test.id() != null;
}
}
On your "way back" (the GET methods) you must ensure the ID is not null with placing the annotation to your DTO. Code could look like this:
#TestIdNull(false)
final Test test = mapper.map(entity, Test.class);
I know it's not a very elegant way but your idea placing the ID in a POST first and then validate is not possible I'm afraid.