Merge Spring data rest links with controller links on same Entity - spring-boot

Question

I would like to combine HATEAOS links to methods on both Controller and Repository.
#RepositoryRestController
#ResponseBody
#ExposesResourceFor(Group.class)
#RequestMapping(value = "/api/v2/groups", produces = MediaTypes.HAL_JSON_VALUE)
public class GroupController {
#Resource
private GroupService groupService;
#RequestMapping(value = "/external", method = POST)
public #ResponseBody PersistentEntityResource saveExternalGroup(
#RequestBody Group newGroup,
PersistentEntityResourceAssembler assembler) {
return assembler.toResource(groupService.saveExternalGroup(newGroup));
}
}
Repository:
#RepositoryRestResource(excerptProjection = GroupSummary.class)
public interface GroupDao extends DefaultDao<Group, Long> {
#NotNull
List<Group> findByState(#Nullable GroupState state);
...other methods...
I would like to achieve to have possibility to go to /api/v2/groups and have there also link to /external. Currently, only links from repository are returned:
"_links": {
"first": {
"href": "http://localhost:8300/api/v2/groups?page=0&size=20"
},
"self": {
"href": "http://localhost:8300/api/v2/groups"
},
"next": {
"href": "http://localhost:8300/api/v2/groups?page=1&size=20"
},
"last": {
"href": "http://localhost:8300/api/v2/groups?page=1&size=20"
},
"profile": {
"href": "http://localhost:8300/api/v2/profile/groups"
},
"search": {
"href": "http://localhost:8300/api/v2/groups/search"
}
},
What should I implement to get there all as above plus something like this:
"external": {
"href": "http://localhost:8300/api/v2/groups/external"
}
Or is there problem with that "/external" is POST? If so, please comment and consider this question with "method=GET".

Answer 1

Option 1:
If it's a one-off, you could add the links in the controller method using the Resource class.
#RequestMapping(value = "/external", method = POST)
public #ResponseBody PersistentEntityResource saveExternalGroup(
#RequestBody Group newGroup,
PersistentEntityResourceAssembler assembler) {
PersistentEntityResource resource = assembler.toResource(groupService.saveExternalGroup(newGroup));
// Replace with ControllerLinkBuilder call, or EntityLinks as you see fit.
resource.add(new Link("http://localhost:8300/api/v2/groups/external","search"));
return resource;
}
Option 2:
If you would like this link to be added to every rendered Resource<Group>, then create a ResourceProcessor component to add it.
#Component
public class GroupResourceProcessor implements ResourceProcessor<Resource<Group>> {
#Override
public Resource<Group> process(Resource<Group> groupResource) {
// Replace with ControllerLinkBuilder call, or EntityLinks as you see fit.
groupResource.add(new Link("http://localhost:8300/api/v2/groups/external","search"));
return groupResource;
}
}