Spring Data REST Controllers vs Custom Controllers - spring-mvc

Question

I have a 2 domain classes one with reference to another like this:
#Document
public class Dummy {
#Id
private UUID id;
private String name;
#Reference
private DummyAttribute dummyAttribute;
// getters and setters omitted.
}
#Document
public class DummyAttribute {
#Id
private UUID id;
private String name;
// getters and setters omitted.
}
I also have 2 repositories corresponding to Dummy and DummyAttribute.
public interface DummyRepository extends CrudRepository<Dummy, UUID> {
}
public interface DummyAttributeRepository extends
CrudRepository<DummyAttribute, UUID> {
}
I want to create a Dummy with a DummyAttribute. So, I create a dummyAttribute by posting to /dummyattributes. I get the response body with a self link to dummyAttribute back. This self link that I get back is used during the creation of Dummy. My JSON payload to the /dummies looks like :
{
"name" : "dummy",
"dummyAttribute" : <self link of dummyAttribute generated during POST>
}
When I do a GET on the association URL generated after POST, I correctly get
the dummyAttribute that was used. So far works well in Spring Data REST.
I want to do the same using my custom controllers. So, I created controllers
for both Dummy and DummyAttribute.
#RestController
public class DummyController {
#Autowired
private DummyRepository dummyRepository;
#Autowired
private DummyResourceProcessor processor;
#RequestMapping(value = "/dummies", method = RequestMethod.POST)
public HttpEntity<Resource<Dummy>> createTenant(#RequestBody Dummy dummy)
{
Dummy save = dummyRepository.save(dummy);
Resource<Dummy> dummyr = new Resource<Dummy>(save);
return new ResponseEntity<Resource<Dummy>>(processor.process(dummyr),
HttpStatus.CREATED);
}
#RequestMapping(value = "/dummies/{id}", method = RequestMethod.GET)
public HttpEntity<Resource<Dummy>> getDummy(#PathVariable("id") Dummy
dummy) {
Resource<Dummy> dummyr = new Resource<Dummy>(dummy);
return new ResponseEntity<Resource<Dummy>>(processor.process(dummyr),
HttpStatus.OK);
}
#RestController
public class DummyAttributeController {
#Autowired
private DummyRepository dummyRepository;
#Autowired
private DummyAttributeRepository dummyAttributeRepository;
#Autowired
private DummyAttributeResourceProcessor processor;
#RequestMapping(value = "/dummyAttributes", method =
RequestMethod.POST)
public HttpEntity<Resource<DummyAttribute>> createDummyAttribute(
#RequestBody DummyAttribute dummyAttribute) {
DummyAttribute save = dummyAttributeRepository.save(dummyAttribute);
Resource<DummyAttribute> dummyr = new Resource<DummyAttribute>(save);
return new ResponseEntity<Resource<DummyAttribute>>
(processor.process(dummyr),createHeaders(request,save.getId()),
HttpStatus.CREATED);
}
#RequestMapping(value = "/dummyAttributes/{id}", method =
RequestMethod.GET)
public HttpEntity<Resource<DummyAttribute>> getDummyAttribute(
#PathVariable("id") DummyAttribute dummyAttribute) {
Resource<DummyAttribute> dummyr = new Resource<DummyAttribute>
(dummyAttribute);
return new ResponseEntity<Resource<DummyAttribute>>
(processor.process(dummyr), HttpStatus.OK);
}
I followed the same sequence of step as above. I did a POST todummyAttribute.
Using this self link , I tried to create a dummy.
This time things are not so smooth. I get this exception back.
Can not instantiate value of type [simple type,
class com.sudo.DummyAttribute] from String value
('http://localhost:8080/dummyAttributes/3fa67f88-f3f9-4efa-a502-
bbeffd3f6025'); no single-String constructor/factory method at
[Source: java.io.PushbackInputStream#224c018a; line: 2, column: 19]
(through reference chain: com.sudo.Dummy["dummyAttribute"])
When I create a constructor inside DummyAttribute, and I parse the id from the url and assign it to the id.
public DummyAttribute(String url) {
String attrId = // parse the URL to get the id;
this.id = attrId;
}
Now things are work as expected.The dummyAttribute is assigned to dummy.
What I would like to know is why are things different when I write my custom-controller ? What am I missing ? How is it that when I use Spring Data REST, the reference URL to the dummyAttribute was automatically resolved to the corresponding dummyAttribute object and in the custom controller, I had to parse it manually and assign the id value explicitly to domainAttribute id?
Also, in the constructor I believe, the dummyAttribute is not resolved by finding it from repository by doing a findOne but a new dummyAttribute is being created. Is this correct?
How do I make my POSTs to my custom controller work exactly like how it works in Spring Data REST ? Do I need a custom serializer/deserializer for this ? Do I need to register some components manually and invoked it ?
I found that when I have customer controllers and #EnableWebMvc is used, the associated resource does not get resolved. That results in the error above. If no #EnableWebMvc is present, then the associated resource gets resolved properly. Not sure how #EnableWebMvc gets in between....
The spring versions that I use are : spring-boot-starter-1.2.5, spring-boot-starter-data-rest-1.2.5, spring-data-commons-1.9.3. spring-hateoas-0.16.0, spring-data-rest-core-2.2.3, spring-data-rest-webmvc-2.2.3.