ADD self link for item in Custom ResponseHandler - spring-data-jpa

Question

I have the following ResponseHandler to override a Data Rest Response Handlers. Instead of returning all data, the handler returns only data for the owner (logged in user- currently hardcoded).
package com.osde.prepo.controller;
import com.osde.prepo.entity.Company;
import com.osde.prepo.repository.CompanyRepository;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.rest.webmvc.RepositoryRestController;
import org.springframework.hateoas.CollectionModel;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import java.util.ArrayList;
import java.util.List;
import static org.springframework.hateoas.server.mvc.WebMvcLinkBuilder.linkTo;
import static org.springframework.hateoas.server.mvc.WebMvcLinkBuilder.methodOn;
/**
* customer controller to override some Data Rest Response Handlers
*/
#RepositoryRestController
public class CompanyController {
Logger logger = LoggerFactory.getLogger(CompanyController.class);
private final CompanyRepository companyRepository;
#Autowired
public CompanyController(CompanyRepository repo) {
companyRepository = repo;
}
#RequestMapping(method = RequestMethod.GET, value = "/companies")
public #ResponseBody
ResponseEntity<?> getAllCompaniesForCurrentUser() {
logger.info("custom implementation for get called!!");
List<Company> companies = new ArrayList<>();
companies = companyRepository.findByOwnerId("google-oauth2|107634743108791790006");
// convert to HATEOAS
CollectionModel<Company> resources = CollectionModel.of(companies);
resources.add(linkTo(methodOn(CompanyController.class)
.getAllCompaniesForCurrentUser())
.withSelfRel());
return ResponseEntity.ok(resources);
}
}
I get the following response, when consuming the API:
{
"_embedded": {
"companies": [
{
"ownerId": "google-oauth2|107634743108791790006",
"name": "Company 1",
"city": "Ort 1",
"country": "Germany",
"profile": "We are 1 ...",
"logoUrl": null
}
]
},
"_links": {
"self": {
"href": "http://localhost:8080/companies"
}
}
}
The original API has the following response (including self-links to the items) How do I have to change my code to get this response (paging is not of interest so far!)?
{
"_embedded": {
"companies": [
{
"ownerId": "google-oauth2|107634743108791790006",
"name": "Company 1",
"city": "Ort 1",
"country": "Germany",
"profile": "We are 1 ...",
"logoUrl": null,
"_links": {
"self": {
"href": "http://localhost:8080/api/companies/1"
},
"company": {
"href": "http://localhost:8080/api/companies/1"
}
}
}
]
},
"_links": {
"self": {
"href": "http://localhost:8080/api/companies/"
},
"profile": {
"href": "http://localhost:8080/api/profile/companies"
},
"search": {
"href": "http://localhost:8080/api/companies/search"
}
},
"page": {
"size": 20,
"totalElements": 1,
"totalPages": 1,
"number": 0
}
}

Answer 1

Here is a sample code to achieve this. I have assumed that your Entity has a getter for id as getId().It can be changed as per the code.
There is a need to extend this RepresentationModel on the entity class to get the add method.
eg
public class Company extends RepresentationModel<Company> implements Serializable {
#RequestMapping(method = RequestMethod.GET, value = "/companies")
public #ResponseBody
ResponseEntity<?> getAllCompaniesForCurrentUser() {
logger.info("custom implementation for get called!!");
List<Company> companies = companyRepository.findByOwnerId("google-oauth2|107634743108791790006");
for (Company company : companies) {
Link selfLink = linkTo(methodOn(CompanyController.class)
.getCompaniesById(company.getId())).withSelfRel();
company.add(selfLink);
}
Link link = linkTo(methodOn(CompanyController.class).getAllCompaniesForCurrentUser()).withSelfRel();
CollectionModel<Company> result = CollectionModel.of(companies, link);
return ResponseEntity.ok().body(companies);
}
There is an another way to do this as well. This won't require any change on the Entity class.
import org.springframework.hateoas.EntityModel;
#RequestMapping(method = RequestMethod.GET, value = "/companies")
public #ResponseBody
ResponseEntity<?> getAllCompaniesForCurrentUser() {
logger.info("custom implementation for get called!!");
List<EntityModel<Company>> companies = companyRepository
.findByOwnerId("google-oauth2|107634743108791790006")
.stream()
.map(this::generateLinks)
.collect(Collectors.toList());
CollectionModel<EntityModel<Company>> resource = CollectionModel.of(companies);
resource.add(entityLinks.linkToCollectionResource(Company.class));
resource.add(entityLinks.linksToSearchResources(Company.class));
return ResponseEntity.ok().body(resource);
}
private EntityModel<Company> generateLinks(Company company) {
EntityModel<Company> resource = EntityModel.of(company);
resource.add(entityLinks.linkToItemResource(Company.class, company.getId()).withSelfRel());
resource.add(entityLinks.linkToCollectionResource(Company.class));
resource.add(entityLinks.linksToSearchResources(Company.class));
return resource;
}

Answer 2

That points to the correct direction!
Now I get the following output:
[
{
"companyId": 1,
"ownerId": "google-oauth2|107634743108791790006",
"name": "Company 1",
"city": "Ort 1",
"country": "Germany",
"profile": "We are 1 ...",
"logoUrl": null,
"links": [
{
"rel": "self",
"href": "http://localhost:8080/api/companies/1"
},
{
"rel": "companies",
"href": "http://localhost:8080/api/companies{?page,size,sort}"
}
]
}
]
How to adjust the following aspects:
link to companies should be on the collection-level and just be http://localhost:8080/api/companies
rename links to _links