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How to design API in Spring MVC?

I have a Spring MVC controller but I'm not sure that it is a good or bad design. As far as I know, api versioning is missing but apart from that I implemented Swagger for documentation and added SpringSecurity and tried to follow YARAS(Yet Another RESTful API Standard) to build it but I need another eye on that to comment it.
#Slf4j
#Controller
#RequestMapping
#RequiredArgsConstructor
public class XGameController implements GameController {
private final GameService gameService;
private final ObjectMapper mapper;
#RequestMapping(value = "/", method= RequestMethod.GET)
public String index() {
return "game";
}
#RequestMapping(value = "/login", method= RequestMethod.GET)
public String login() {
return "login";
}
#Secured("ROLE_USER")
#RequestMapping(value = "/games", method= RequestMethod.POST)
public String initializeGame(Model model) {
log.info("New XGame is initializing...");
Game game = new Game();
game = gameService.initializeGame(game.getId());
try {
model.addAttribute("game", mapper.writeValueAsString(game));
} catch (JsonProcessingException e) {
log.error(e.getMessage());
}
log.info("New XGame is initialized successfully!");
return "game";
}
#Secured("ROLE_USER")
#RequestMapping(value = "/games/{gameId}", method= RequestMethod.PUT)
public #ResponseBody Game play(#PathVariable("gameId") String gameId,
#RequestParam Integer pitNumber,
#RequestParam String action) {
log.info("Sowing stone is triggered...");
return gameService.executeGameRules(UUID.fromString(gameId), pitNumber);
}
#RequestMapping(value = "/403", method= RequestMethod.GET)
public String error403() {
return "/error/403";
}
}
My swagger snapshot;

I would make some changes.
In /games/{gameId} I would use PATCH instead of PUT. The reason is that PUT is intended to completely replace the resource (in your case, the Game). This does not seem to be what you are doing in this endpoint. PATCH is intended to partially update a resource, which seems much more suited to what you are doing here.
Still in /games/{gameId} I would use the request body to provide the needed data instead of query parameters. It simply doesn't seem right. Query parameters are way more suited to GET requests than to POST, PUT or PATCH.
I would rename /403 to something else that actually gives some context about what 403 is. Having said this, I would go with /error-pages/403. Additionally, I would also consider removing this endpoint from the swagger specification.
Other than this, it seems fine to me.

Some advices :
Use a path that represents the context or the idea of your controller and you can add the version
#RequestMapping("/V1/xgame")
Use specialized annotations such as : #GetMapping, #PostMapping etc...
For /403 use a meaning full name such as /errors
Use custom message that you will return to the users. For that you need a ControllerAdvice.
Google on patterns and best practices Rest API design
Read some books for better undertanding.

Firstly, instead of #RequestMapping use a specific Mapping(Get, Post,etc.) and the use of type of mapping is up to you which you find more particular to the cause of using it
if you are redirecting from a page to homepage try to use return "redirect:"/url"" instead of just returning HTML file directly.
Rename your method for error, RequestMapping value to some more reasonable name.
instead of using return "/error/403"
use return "redirect:/error/403"

How can I override a Spring Data REST method without disabling default implementations

I finally found a way to override methods of Spring Data REST with a custom implementation. Unfortunately this disables the default handling.
My Repository should contain findAll and findById exposed over the GET: /games and GET: /games/{id} respectively and save should not be exported because it is overriden by the controller.
#RepositoryRestResource(path = "games", exported = true)
public interface GameRepository extends Repository<Game, UUID> {
Collection<Game> findAll();
Game findById(UUID id);
#RestResource(exported = false)
Game save(Game game);
}
My controller should handle POST: /games, generate the game on the server and return the saved Game.
#RepositoryRestController
#ExposesResourceFor(Game.class)
#RequestMapping("games")
public class CustomGameController {
private final GameService gameService;
public CustomGameController(GameService gameService) {
this.gameService = gameService;
}
#ResponseBody
#RequestMapping(value = "", method = RequestMethod.POST, produces = "application/hal+json")
public PersistentEntityResource generateNewGame(#RequestBody CreateGameDTO createGameDTO, PersistentEntityResourceAssembler assembler) {
Game game = gameService.generateNewGame(createGameDTO);
return assembler.toFullResource(game);
}
}
However when I try to GET: /games it returns 405: Method Not Allowed but POST: /games works as intended. When I change the value of the generateNewGame mapping to "new" all three requests work. But POST: /games/new is no RESTful URL Layout and I would rather avoid it. I don't understand why I get this behaviour and how I may solve it. Does anybody have a clue?

Use #BasePathAwareControllerannotation above your controller to preserve default spring data rest paths and add new custom path base on your need. Although overwrite default spring data rest path.
#BasePathAwareController
public class CustomGameController {
private final GameService gameService;
public CustomGameController(GameService gameService) {
this.gameService = gameService;
}
#ResponseBody
#RequestMapping(value = "", method = RequestMethod.POST, produces =
"application/hal+json")
public PersistentEntityResource generateNewGame(#RequestBody CreateGameDTO
createGameDTO, PersistentEntityResourceAssembler assembler) {
Game game = gameService.generateNewGame(createGameDTO);
return assembler.toFullResource(game);
}
}

Maybe you can do something we usually do in Linux. Set a fake path and link to it.
POST /games ==> [filter] request.uri.euqal("/games") && request.method==POST
==> Redirect /new/games
What you see also is /games.
Don't use /games/new, it may be conflict with things inner Spring.

Prevents HTTP method in spring-data-rest

I'm using spring-data-rest.
Given following repository :
#RepositoryRestResource
public interface MyRepository extends PagingAndSortingRepository<MyEntity, Long> {}
The annotation #RestResource(exported = false) on the save() method makes the framework return a 405 Method Not Allowed error when using methods POST, PUT and PATCH.
My question : How can I just return a 405 error on PUT method while POST and PATCH are still allowed for this repository ?
Thanks !

#SWiggels
Thanks for your response :)
Your solution didn't work for me... PUT is always allowed.
For others I found this one that worked :
#BasePathAwareController
public class MyEntityController {
#RequestMapping(value = "/myentity/{id}", method = RequestMethod.PUT)
public ResponseEntity<?> preventsPut() {
return new ResponseEntity<>(HttpStatus.METHOD_NOT_ALLOWED);
}
}

You can add your allowed methods in the response of the options-probe.
#RequestMapping(method = RequestMethod.OPTIONS)
ResponseEntity<Void> getProposalsOptions() {
HttpHeaders headers = new HttpHeaders();
headers.setAllow(new HashSet<>(Arrays.asList(OPTIONS, PATCH, POST)));
return new ResponseEntity<>(headers, HttpStatus.NO_CONTENT);
}
This allows only Options, Patch, Post as request-methods. For every other tried method you get a HTTP-405-Error.

Spring Rest Controller, Path Variables on an overriden method's arguement

I have a controller annotated with #RestController and it implements an interface:
public interface ContratEndpoint {
String ROOT = "/api/contrats";
String GET_CONTRAT = "";
String GET_CONTRAT_PER_PK = "/{idContrat}";
#RequestMapping(value = GET_CONTRAT)
Contrat getContrat(#RequestParam(value = "contratId")Long contratId);
#RequestMapping(value = GET_CONTRAT_PER_ID)
ExtContrat getContratById(#PathVariable("idContrat") Long idContrat);
}
The controller:
#RestController
#RequestMapping(value = ContratEndpoint.ROOT)
public class ContratController implements ContratEndpoint {
//Injecting Services....
#Resource
private Mapper mapper;
#Override
public Contrat getContrat(Long contratId) {
return mapper.map(contratService.get(contratId),Contrat.class);
}
#Override
public ExtContrat getContratById(#PathVariable("idContrat") Long idContrat){
Preconditions.checkArgument(idContrat !=null);
return mapper.map(contratService.get(idContrat),ExtContrat.class);
}
.The above Code works just fine.
. But For the first inherited method , I didn't have to annotate arguments with #RequestParam and it worked just fine.
As for the second method I tried at first :
#Override
public ExtContrat getContratById(Long idContrat){
Preconditions.checkArgument(idContrat !=null);
return mapper.map(contratService.get(idContrat),ExtContrat.class);
}
. I expected the same behaviour Like the first Method, But i was wrong and the code ended up firing an IllegalArgumentException because of the check in ligne Preconditions.checkArgument(idContrat!=null).
My question is what is so specific about #PathVariable that i've missed ?
Or is it just something is wrong with my approach?
Thanks.

There is difference between Request param and path variable,seee below post that you can confirm with your uri the cause for the exception :
#PathVariable is to obtain some placeholder from the uri (Spring call it an URI Template) — see Spring Reference Chapter 16.3.2.2 URI Template Patterns
#RequestParam is to obtain an parameter — see Spring Reference Chapter 16.3.3.3 Binding request parameters to method parameters with #RequestParam
Assume this Url http://localhost:8080/SomeApp/user/1234/invoices?date=12-05-2013 (to get the invoices for user 1234 for today)
#RequestMapping(value="/user/{userId}/invoices", method = RequestMethod.GET)
public List<Invoice> listUsersInvoices(
#PathVariable("userId") int user,
#RequestParam(value = "date", required = false) Date dateOrNull) {
...
}

Spring Rest RequestMethod.GET returns 400 Bad Request for #RequestParam required=true when missing

I am new to Spring and Rest Endpoints.
I have a controller, which accepts #RequestParam and returns a JSON Response.
By default the #RequestParam required = "true", which is how I need it.
I am using Spring 3.1.3
This is my Get Method in the controller:
#Controller
#RequestMapping("/path")
public class MyController{
#RequestMapping(value = "/search/again.do", method = RequestMethod.GET, produces = {
"application/json"
})
public ResponseEntity<?> find(#RequestParam(value = "test", required = true) final String test) {
return new ResponseEntity<String>("Success ", HttpStatus.OK);
}
}
When I send a get with the request param it hits the endpoint , which is how I expect.
Example : path/search/again.do?test=yes
Everything is perfect.
This is where I am having issue:
When I send a Get with that value missing:
Example: path/search/again.do
I get a 400 Bad Request. May be this is correct.
But what I want to achieve is. When the required value is missing in the GET request.
I can send a JSON response as that #RequestParam Value test is missing.
Can anybody guide me how to achieve this.
I am not sure what I am missing.
Thanks in advance.

If you look closely at your code, you'll see that the answer is staring right at you. Just change required to false and you should be good to go. When the user doesn't provide a value for GET parameter test, then you can return a special message.
#Controller
#RequestMapping("/path")
public class MyController {
#RequestMapping(value = "/search/again.do", method = RequestMethod.GET, produces = {
"application/json"
})
public ResponseEntity<?> find(#RequestParam(value = "test", required = false) final String test) {
if (test == null) {
return new ResponseEntity<String>("test parameter is missing", HttpStatus.OK);
}
else {
return new ResponseEntity<String>("Success ", HttpStatus.OK);
}
}
}

Solution 1: You can use custom #ExceptionHandler in your controller, e.g
#ExceptionHandler(MissingServletRequestParameterException.class)
public ResponseEntity<?> paramterValidationHandler(HttpServletResquest request){
//validate the request here and return an ResponseEntity Object
}
Solution 2: Would be custom spring ErrorController which I never have tried myself but it possible to override it.
Solution 3: You can write an ControllerAdvice for a global controller exception handling.

Well if you set the parameter test is required. U just can't send the request without that param. Try to change the param required= false and handle the missing param in the method. You can us something likeif(test==null) throw new Exception("Param test missing")