JAX-RS - Performing Entity Validation by Using @Valid

Request entity bodies can be mapped to resource method parameters as Java bean (explained here). Entity validation can be enabled by using @Valid with such entity parameters, given that the Java bean class is decorated with Bean Validation annotations.

Example

A JAX-RS resource

@Path("/customers")
public class CustomerResource {

    @POST
    public String createCustomer(@Valid Customer customer) {
        System.out.println("-- in createCustomer() method --");
        return String.format("Customer created : %s%n", customer);
    }
}

The Java Bean

@XmlRootElement
public class Customer {
    @NotNull
    private String name;
    @NotNull
    private String address;
    @NotNull
    @Pattern(regexp = "\\d{3}-\\d{3}-\\d{4}")
    private String phoneNumber;
    .............
}

Writing an ExceptionMapper

We are going to write an exception Mapper to return a custom validation error message.

@Provider
public class MyExceptionMapper
                 implements ExceptionMapper<ConstraintViolationException> {

    @Override
    public Response toResponse(final ConstraintViolationException exception) {
        return Response.status(Response.Status.BAD_REQUEST)
                       .entity(prepareMessage(exception))
                       .type("text/plain")
                       .build();
    }

    private String prepareMessage(ConstraintViolationException exception) {
        String msg = "";
        for (ConstraintViolation<?> cv : exception.getConstraintViolations()) {
            msg+=cv.getPropertyPath()+" "+cv.getMessage()+"\n";
        }
        return msg;
    }
}

mvn tomcat7:run-war

JAX-RS client

public class MyClient {

    public static void main(String[] args) throws Exception {
        Customer customer = new Customer();
        customer.setName(null);
        customer.setAddress(null);
        customer.setPhoneNumber("343-343-343");

        Client client = ClientBuilder.newBuilder().build();
        WebTarget target =
                client.target("http://localhost:8080/customers");
        Response response = target.request()
                                .post(Entity.entity(customer,
                                        MediaType.TEXT_XML), Response.class);
        System.out.println(response.readEntity(String.class));
    }
}

Output

createCustomer.arg0.address may not be null
createCustomer.arg0.phoneNumber must match "\d{3}-\d{3}-\d{4}"
createCustomer.arg0.name may not be null

Example Project

Dependencies and Technologies Used:

• jersey-server 2.25.1: Jersey core server implementation.
• jersey-container-servlet 2.25.1: Jersey core Servlet 3.x implementation.
• jersey-bean-validation 2.25.1: Jersey extension module providing support for Bean Validation (JSR-349) API.
• JDK 1.8
• Maven 3.3.9