Guy Yafe Guy Yafe - 1 month ago 6
reST (reStructuredText) Question

Jersey: Unable to Get Sub-Sub-Resource

I have a web application implementing REST API using Jersey. The web container id Tomcat

Here is a summary of the API:

/rest/patients


Gets a list of patients' metadata.

/rest/patients/{id}


Gets detailed data about a specific patient.

/rest/patients/{id}/visits


Gets a list of visits` metadata for a specific patient.

/rest/patients/{id}/visits/{visitId}


Gets detailed data about a specific visit of a specific patient.

My problem is that I can't get the sub-sub resources. For example, when I request
/rest/patients/1
the detailed data of patient #1 is received correctly.

But when I request
/rest/patients/1/visits
I get 404 error, and the flow doesn't even enter the
getVisits()
method.

It looks like that when a request for a specific patient id received (
patients/{id}
), Jersey is directing it correctly from
PatientsMetadataResource
to
PatientsResource
.

But when a visits sub-sub-resource is being requested (
patients/{id}/visits
), Jersey doesn't direct it into the
PatientsResource
.

So how can I direct a sub resource along with all of its sub-sub resources into the same class?

Code for
PatientsMetadataResource
(The name is a bit vague, and I need to change it):

@Path("/patients")
public class PatientsMetadataResource {

@GET
@Produces(MediaType.APPLICATION_JSON)
public Response getPatients(@QueryParam("page") int pageIndex) {
//.... Loads, Builds and returns the patients' metadata list correctly
}

@GET
@Produces(MediaType.APPLICATION_JSON)
@Path("/{uid:\\d+}")
public PatientResource getPatient(@PathParam("uid") int uid) {
return new PatientResource(uid);
}

}


Code for
PatientResource
:

public class PatientResource {

private final int uid;

public PatientResource(int uid) {
this.uid = uid;
}

@GET
@Produces(MediaType.APPLICATION_JSON)
public Response getPatient() {
//Returns the patient correctly
System.out.println("A Patient was asked");
Patient patient = PersistentDataProvider.loadPatientByUid(uid);
return Response.ok(patient).build();
}

@GET
@Path("/visits")
@Produces(MediaType.APPLICATION_JSON)
public VisitsResource getVisits(@PathParam("uid") int patientUid) {
//The flow doesn't even enter here. A 404 is being returned instead.
System.out.println("Visits were asked");
return new VisitsResource(patientUid);
}
}


Code for Jersey part in web.xml:

<servlet>
<servlet-name>Jersey REST Service</servlet-name>
<servlet-class>
com.sun.jersey.spi.container.servlet.ServletContainer
</servlet-class>
<init-param>
<param-name>com.sun.jersey.config.property.packages</param-name>
<param-value>il.co.site_building.dvardy.resources</param-value>
</init-param>
<init-param>
<param-name>com.sun.jersey.api.json.POJOMappingFeature</param-name>
<param-value>true</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Jersey REST Service</servlet-name>
<url-pattern>/rest/*</url-pattern>
</servlet-mapping>

Answer

Sub-Resource Locators aren't supposed to have HTTP method annotations

// @GET    <--- Remove this
// @Produces(MediaType.APPLICATION_JSON)
@Path("/{uid:\\d+}")
public PatientResource getPatient(@PathParam("uid") int uid) {
   return new PatientResource(uid);
}

Their main purpose is simply to forward request to the sub-resource class, not GET/POST/etc anything. When Jersey sees that HTTP method annotation, it no longer gets treated as a sub-resource locator.

Also you don't need need to pass the id. It will get passed accordingly

@Path("parent")
class ParentResource {
    @Path("{id}")
    public ChildResource  getChild() {
      return new ChildResource();
    }
}

class ChildResource {
    @GET
    public Response get(@PathParam("id") long id) {}

    @GET
    @Path("something")
    public Response something(@PathParam("id") long id) {}
}

Here GET 'parent/1' goes to ChildResource.get, passing the path param and GET parent/1/something goes to ChilsResource.something, passing the path param

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