Please see my question embedded in the comments section of the code below -
// This should return a list of all ids and their name and status info, e.g. as json
public Mono<ServerResponse> f1(String originalId) {
// this gives list of ids which are comma separated
Mono<String> ids = f2(originalId);
ids.flatMapIterable(line -> Arrays.asList(line.split(COMMA)))
.doOnNext(id -> {
Mono<String> idName = f3(id);
Mono<String> idStatus = f4(id);
Mono<Tuple2<String, String>> combined = Mono.zip(idName, idStatus);
// How do i return all the combined Mono tuples as Mono<ServerResponse>
}).subscribe();
// Need to return proper Mono - not empty
return Mono.empty();
}
Also I am not sure whether I should return a Flux or a Mono as return type of f1() as its a list of ids and their respective values
You need to return Mono<ServerResponse>.
public Mono<ServerResponse> f1(String key) {
Mono<String> ids = f2(key);
Flux<IdInfo> idInfoFlux = ids.flatMapIterable(line -> Arrays.asList(line.split(",")))
.flatMap(id -> {
Mono<String> idName = getIdName(id);
Mono<String> idStatus = getIdStatus(id);
return Mono.zip(idName, idStatus, (name, status) -> new IdInfo(name, status));
})
.doOnNext(id -> System.out.println(id));
return ServerResponse.ok().contentType(MediaType.APPLICATION_JSON).body(idInfoFlux, IdInfo.class);
}
// your DTO class that you would like to pass in response as json
public static class IdInfo {
String idName;
String idStatus;
public IdInfo(String idName, String idStatus) {
this.idName = idName;
this.idStatus = idStatus;
}
public String toString() {
return String.format("IdInfo [idName=%s, idStatus=%s]", idName, idStatus);
}
}
Related
I am new to reactive and not able to get around this.
I have following Dtos:
public class User {
int id;
Map<String, Car> carsMap;
}
public class Car {
String carName;
}
// Response object
public class VehiclesInfo {
List<String> vehicleName;
}
From database I am getting Mono<User> when querying by userId.
And I have to return Mono<VehiclesInfo>.
So, I have to map the carsMap received from Mono<User> into List i.e. List of carName and set that into VehiclesInfo and return that as Mono i.e. Mono<VehiclesInfo>.
I am doing it like below. Please let me know how this can be done without blocking.
// userMono is returned by database query
Mono<User> userMono = getUserInfoById(userId);
Optional<User> userOptional = userMono.blockOptional();
if (userOptional.isPresent()) {
User user1 = userOptional.get();
Flux<Car> carFlux = Flux.fromIterable(user1.getCarsMap().keySet())
.flatMap(i -> {
final Car c = new Car();
c.setCarName(i);
return Mono.just(c);
});
carFlux.subscribe(c -> System.out.println(c.getCarName()));
}
I am new to Reactive programming and I got stuck writing a custom Insert query.
So far I have a FriendshipRepository.java class.
public interface FriendshipRepository extends R2dbcRepository<Friendship, String> {
#Query(value = "INSERT INTO public.friendship(requester_id, addressee_id) values (:requesterid::uuid, :addresseeid::uuid)")
public Mono<Void> insertFriendRequest(
#Param("requesterid") String requesterId,
#Param("addresseeid") String addresseeId
);
}
And a FriendshipController.java class.
#RestController
public class FriendsController {
private final FriendshipRepository friendshipRepository;
public FriendsController(FriendshipRepository friendshipRepository) {
this.friendshipRepository = friendshipRepository;
}
#PostMapping(value = "/request", produces = "application/json")
public Mono<ResponseEntity<RequestResponse>> sendFriendRequest(#RequestBody FriendRequest friendRequest, #AuthenticationPrincipal Mono<User> principal) throws Exception {
String id = principal.map(User::getId).toFuture().get();
return friendshipRepository.insertFriendRequest(id, friendRequest.getUserId()).log()
.then(Mono.just("NEXT"))
.map(e -> {
return ResponseEntity.status(HttpStatus.CREATED).body(new RequestResponse("Success", ResponseCode.SUCCESS));
}).onErrorResume(e -> {
return Mono.just(ResponseEntity.status(HttpStatus.FORBIDDEN).body(new RequestResponse("Friend request was unsuccessful ", ResponseCode.REFUSED)));
});
}
}
This is a working example.
But I dont understand why I have to call .then(Mono.just("NEXT")) and create a new Mono to be able to return a custom ResponseEntity<RequestResponse>>. I also tried merge the the whole process. I meen by this at the begining when I get the Id from the ReactiveSpringSecutiryContext that is a blocking line of code and If I know it correctly that is a bad approach in Reactive programming.
I tried this approach but in this case, I can only retrun the Id of the user.
Mono<String> userId = principal.map(User::getId);
return userId.doOnNext(id -> {
friendshipRepository.insertFriendRequest(id, friendRequest.getUserId()).log()
.map(e -> {
return ResponseEntity.status(HttpStatus.CREATED).body(new RequestResponse("SIKER", ResponseCode.SUCCESS));
})
.onErrorResume(e -> {
return Mono.just(ResponseEntity.status(HttpStatus.FORBIDDEN).body(new RequestResponse("Friend request was unsuccessful ", ResponseCode.REFUSED)));
}).subscribe();
// .doOnSuccess(e -> ServerResponse.noContent().build((new RequestResponse("SIKER", ResponseCode.SUCCESS)), Void.class));
});
How could I rewrite this endpoint? Or does my whole approach inaproptirate?
Thank you in advance for your help.
Probably not the nicest solution, but better then it was.
My query:
public interface FriendshipRepository extends R2dbcRepository<Friendship, String> {
#Query(value = "INSERT INTO public.friendship(requester_id, addressee_id) values (:requesterid::uuid, :addresseeid::uuid) RETURNING id")
public Mono<String> insertFriendRequest(
#Param("requesterid") String requesterId,
#Param("addresseeid") String addresseeId
);
}
My api:
#PostMapping(value = "/request", produces = "application/json")
public Mono<ResponseEntity<RequestResponse>> sendFriendRequest(#RequestBody FriendRequest friendRequest, #AuthenticationPrincipal Mono<User> principal) throws Exception {
String id = principal.map(User::getId).toFuture().get();
return friendshipRepository.insertFriendRequest(id, friendRequest.getUserId()).log()
.map(e -> {
return ResponseEntity.status(HttpStatus.CREATED).body(new RequestResponse("Success", ResponseCode.SUCCESS));
}).onErrorResume(e -> {
return Mono.just(ResponseEntity.status(HttpStatus.FORBIDDEN).body(new RequestResponse("Friend request was unsuccessful ", ResponseCode.REFUSED)));
});
}
In case no email was found in the database the findByEmail returns null, so it breaks all the process
public Mono<UserDto> findByEmail(String email) {
return this.userRepository.findByEmail(email) // <---- ERROR HERE
.map(userEntity -> userMapper.toDto(userEntity)) // <---- ERROR HERE
.switchIfEmpty(Mono.empty());
}
#Override
public Mono<String> authenticate(String accessToken) {
return this.facebookService.verifyAccessToken(accessToken)
.flatMap(userFacebookDto ->
this.findByEmail(userFacebookDto.getEmail())
.map(userDbDto -> {
String token = "";
if (isNull(userDbDto)) {
UserEntity userEntity = this.userFacebookMapper.toEntity(userFacebookDto);
this.userRepository.save(userEntity)
.map(ue -> this.jwtTokenUtil.generateToken(ue));
} else {
token = jwtTokenUtil.generateToken(this.userMapper.toEntity(null));
}
return token;
})
);
}
What is on your opinion a good chaining strategy for this case in order to continue the execution of the rest of the code ?
The error :
"The mapper returned a null Mono"
In Spring Reactive Java how can I write an updateById() method using the Router and Handler?
For example, the Router has this code:
RouterFunctions.route(RequestPredicates.PUT("/employees/{id}").and(RequestPredicates.accept(MediaType.APPLICATION_JSON))
.and(RequestPredicates.contentType(MediaType.APPLICATION_JSON)),
employeeHandler::updateEmployeeById);
My question is how to write the employeeHandler::updateEmployeeById() keeping the ID as same but changing the other members of the Employee object?
public Mono<ServerResponse> updateEmployeeById(ServerRequest serverRequest) {
Mono<Employee> employeeMono = serverRequest.bodyToMono(Employee.class);
<And now what??>
return ServerResponse.ok().contentType(MediaType.APPLICATION_JSON).body(employeeMono, Employee.class);
}
The Employee class looks like this:
#Document
#Data
#AllArgsConstructor
#NoArgsConstructor
public class Employee {
#Id
int id;
double salary;
}
Thanks for any help.
First of all, you have to add ReactiveMongoRepository in your classpath. You can also read about it here.
#Repository
public interface EmployeeRepository extends ReactiveMongoRepository<Employee, Integer> {
Mono<Employee> findById(Integer id);
}
Then your updateEmployeeById method can have the following structure:
public Mono<ServerResponse> updateEmployeeById(ServerRequest serverRequest) {
return serverRequest
.bodyToMono(Employee.class)
.doOnSubscribe(e -> log.info("update employee request received"))
.flatMap(employee -> {
Integer id = Integer.parseInt(serverRequest.pathVariable("id"));
return employeeRepository
.findById(id)
.switchIfEmpty(Mono.error(new NotFoundException("employee with " + id + " has not been found")))
// what you need to do is to update already found entity with
// new values. Usually map() function is used for that purpose
// because map is about 'transformation' what is setting new
// values in our case
.map(foundEmployee -> {
foundEmployee.setSalary(employee.getSalary());
return foundEmployee;
});
})
.flatMap(employeeRepository::save)
.doOnError(error -> log.error("error while updating employee", error))
.doOnSuccess(e -> log.info("employee [{}] has been updated", e.getId()))
.flatMap(employee -> ServerResponse.ok().contentType(MediaType.APPLICATION_JSON).body(BodyInserters.fromValue(employee), Employee.class));
}
UPDATE:
Based on Prana's answer, I have updated the code above merging our solutions in one. Logging with a help of Slf4j was added. And switchIfEmpty() functions for the case when the entity was not found.
I would also suggest your reading about global exception handling which will make your API even better. A part of it I can provide here:
/**
* Returns routing function.
*
* #param errorAttributes errorAttributes
* #return routing function
*/
#Override
protected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) {
return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse);
}
private HttpStatus getStatus(Throwable error) {
HttpStatus status;
if (error instanceof NotFoundException) {
status = NOT_FOUND;
} else if (error instanceof ValidationException) {
status = BAD_REQUEST;
} else {
status = INTERNAL_SERVER_ERROR;
}
return status;
}
/**
* Custom global error handler.
*
* #param request request
* #return response
*/
private Mono<ServerResponse> renderErrorResponse(ServerRequest request) {
Map<String, Object> errorPropertiesMap = getErrorAttributes(request, false);
Throwable error = getError(request);
HttpStatus errorStatus = getStatus(error);
return ServerResponse
.status(errorStatus)
.contentType(APPLICATION_JSON)
.body(BodyInserters.fromValue(errorPropertiesMap));
}
A slightly different version of the above worked without any exceptions:
public Mono<ServerResponse> updateEmployeeById(ServerRequest serverRequest) {
Mono<ServerResponse> notFound = ServerResponse.notFound().build();
Mono<Employee> employeeMono = serverRequest.bodyToMono(Employee.class);
Integer employeeId = Integer.parseInt(serverRequest.pathVariable("id"));
employeeMono = employeeMono.flatMap(employee -> employeeRepository.findById(employeeId)
.map(foundEmployee -> {
foundEmployee.setSalary(employee.getSalary());
return foundEmployee;
})
.flatMap(employeeRepository::save));
return ServerResponse.ok().contentType(MediaType.APPLICATION_JSON).body(employeeMono, Employee.class).switchIfEmpty(notFound);
}
Thanks to Stepan Tsybulski.
I am playing with Spring's WebClient. The primary implementation of the REST endpoints (in DemoPOJORouter and DemoPOJOHandler) seem to work. Also, the http.Get endpoint in DemoClientRouter and DemoClientHandler seems to work.
But, the http.Post for the DemoClient implementation "does nothing". It returns success (200), but nothing gets added to the dummy repo. I have a feeling that I need to do something in DemoClient to cause the http.Post endpoint in DemoPOJOHandler to actually execute (i.e., I believe neither the statements in DemoPOJOService.add() nor DemoPOJORepo.add() are being executed).
Based on prior pratfalls in WebFlux/reactive/functional efforts, I have a feeling that I'm not successfully subscribing, and so the statements never are invoked. But, I'm having difficulty identifying the "why".
Test code follows...
DemoClient router...
#Configuration
public class DemoClientRouter {
#Bean
public RouterFunction<ServerResponse> clientRoutes(DemoClientHandler requestHandler) {
return nest(path("/v2"),
nest(accept(APPLICATION_JSON),
RouterFunctions.route(RequestPredicates.GET("/DemoClient/{id}"), requestHandler::getById)
.andRoute(RequestPredicates.POST("/DemoClient"), requestHandler::add)));
}
}
DemoClient handler...
#Component
public class DemoClientHandler {
public static final String PATH_VAR_ID = "id";
#Autowired
DemoClient demoClient;
public Mono<ServerResponse> getById(ServerRequest request) {
Mono<DemoPOJO> monoDemoPOJO;
int id;
// short-circuit if bad request or invalid value for id
id = getIdFromServerRequest(request);
if (id < 1) {
return ServerResponse.badRequest().build();
}
// non-blocking mechanism for either returning the Mono<DemoPOJO>
// or an empty response if Mono<Void> was returned by repo.getById()
return demoClient.getById(id).flatMap(demoPOJO -> ServerResponse.ok()
.contentType(MediaType.APPLICATION_JSON)
.body(Mono.just(demoPOJO), DemoPOJO.class))
.switchIfEmpty(ServerResponse.notFound().build());
}
public Mono<ServerResponse> add(ServerRequest request) {
return request.bodyToMono(DemoPOJO.class).doOnSuccess( demoPOJO -> demoClient.add(demoPOJO))
.then(ServerResponse.ok().build())
.onErrorResume(e -> simpleErrorReporter(e))
.switchIfEmpty(ServerResponse.badRequest().build());
}
private int getIdFromServerRequest(ServerRequest request) {
Map<String, String> pathVariables = request.pathVariables();
int id = -1;
// short-circuit if bad request
// should never happen, but if this method is ever called directly (vice via DemoPOJORouter)
if ((pathVariables == null)
|| (!pathVariables.containsKey(PATH_VAR_ID))) {
return id;
}
try {
id = Integer.parseInt(pathVariables.get(PATH_VAR_ID));
} catch (NumberFormatException e) {
// swallow the error, return value <0 to signal error
id = -1;
}
return id;
}
private Mono<ServerResponse> simpleErrorReporter(Throwable e) {
return ServerResponse.badRequest()
.contentType(MediaType.TEXT_PLAIN)
.syncBody(e.getMessage());
}
}
DemoClient impl...
#Component
public class DemoClient {
private final WebClient client;
public DemoClient() {
client = WebClient.create();
}
public Mono<DemoPOJO> getById(int id) {
return client.get().uri("http://localhost:8080/v2/DemoPOJO/" + id)
.accept(MediaType.APPLICATION_JSON)
.exchange()
.flatMap(response -> response.bodyToMono(DemoPOJO.class));
}
public Mono<Boolean> add(DemoPOJO demoPOJO) {
return client.post().uri("http://localhost:8080/v2/DemoPOJO")
.syncBody(demoPOJO)
.exchange()
.flatMap(response -> response.bodyToMono(Boolean.class));
}
}
And, the DemoPOJO stuff, starting with DemoPOJORouter...
#Configuration
public class DemoPOJORouter {
#Bean
public RouterFunction<ServerResponse> demoPOJORoute(DemoPOJOHandler requestHandler) {
return nest(path("/v2"),
nest(accept(APPLICATION_JSON),
RouterFunctions.route(RequestPredicates.GET("/DemoPOJO/{id}"), requestHandler::getById)
.andRoute(RequestPredicates.POST("/DemoPOJO"), requestHandler::add)));
}
}
DemoPOJOHandler...
#Component
public class DemoPOJOHandler {
public static final String PATH_VAR_ID = "id";
#Autowired
private DemoPOJOService service;
public Mono<ServerResponse> getById(ServerRequest request) {
Mono<DemoPOJO> monoDemoPOJO;
int id;
// short-circuit if bad request or invalid value for id
id = getIdFromServerRequest(request);
if (id < 1) {
return ServerResponse.badRequest().build();
}
// non-blocking mechanism for either returning the Mono<DemoPOJO>
// or an empty response if Mono<Void> was returned by repo.getById()
return service.getById(id).flatMap(demoPOJO -> ServerResponse.ok()
.contentType(MediaType.APPLICATION_JSON)
.body(Mono.just(demoPOJO), DemoPOJO.class))
.switchIfEmpty(ServerResponse.notFound().build());
}
public Mono<ServerResponse> add(ServerRequest request) {
return request.bodyToMono(DemoPOJO.class).doOnSuccess( demoPOJO -> service.add(demoPOJO))
.then(ServerResponse.ok().build())
.onErrorResume(e -> simpleErrorReporter(e))
.switchIfEmpty(ServerResponse.badRequest().build());
}
private int getIdFromServerRequest(ServerRequest request) {
Map<String, String> pathVariables = request.pathVariables();
int id = -1;
// short-circuit if bad request
// should never happen, but if this method is ever called directly (vice via DemoPOJORouter)
if ((pathVariables == null)
|| (!pathVariables.containsKey(PATH_VAR_ID))) {
return id;
}
try {
id = Integer.parseInt(pathVariables.get(PATH_VAR_ID));
} catch (NumberFormatException e) {
// swallow the exception, return illegal value to signal error
id = -1;
}
return id;
}
private Mono<ServerResponse> simpleErrorReporter(Throwable e) {
return ServerResponse.badRequest()
.contentType(MediaType.TEXT_PLAIN)
.syncBody(e.getMessage());
}
}
DemoPOJOService...
#Component
public class DemoPOJOService {
#Autowired
private DemoPOJORepo demoPOJORepo;
public Mono<DemoPOJO> getById(int id) {
DemoPOJO demoPOJO = demoPOJORepo.getById(id);
return (demoPOJO == null) ? Mono.empty()
: Mono.just(demoPOJO);
}
public Mono<Boolean> add(DemoPOJO demoPOJO) {
return Mono.just(demoPOJORepo.add(demoPOJO));
}
}
DemoPOJORepo...
#Component
public class DemoPOJORepo {
private static final int NUM_OBJS = 5;
private static DemoPOJORepo demoRepo = null;
private Map<Integer, DemoPOJO> demoPOJOMap;
private DemoPOJORepo() {
initMap();
}
public static DemoPOJORepo getInstance() {
if (demoRepo == null) {
demoRepo = new DemoPOJORepo();
}
return demoRepo;
}
public DemoPOJO getById(int id) {
return demoPOJOMap.get(id);
}
public boolean add(DemoPOJO demoPOJO) throws InvalidParameterException {
// short-circuit on null pointer or duplicate id
if (demoPOJO == null) {
throw new InvalidParameterException("Add failed, null object detected...");
} else if (demoPOJOMap.containsKey(demoPOJO.getId())) {
throw new InvalidParameterException("Add failed, duplicate id detected...");
}
demoPOJOMap.put(demoPOJO.getId(), demoPOJO);
// if the return statement is reached, then the new demoPOJO was added
return true;
}
}
Finally, DemoPOJO...
public class DemoPOJO {
public static final String DEF_NAME = "DEFAULT NAME";
public static final int DEF_VALUE = 99;
private int id;
private String name;
private int value;
public DemoPOJO(int id) {
this(id, DEF_NAME, DEF_VALUE);
}
public DemoPOJO(#JsonProperty("id") int id, #JsonProperty("name") String name, #JsonProperty("value") int value) {
this.id = id;
this.name = name;
this.value = value;
}
/*
* setters and getters go here
*/
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append(id);
builder.append(" :: ");
builder.append(name);
builder.append(" :: ");
builder.append(value);
return builder.toString();
}
}
Here is probably your problem.
DemoPOJOHandler.class
request.bodyToMono(DemoPOJO.class).doOnSuccess(demoPOJO -> service.add(demoPOJO))
DemoPOJOService.class
public Mono<Boolean> add(DemoPOJO demoPOJO) {
return Mono.just(demoPOJORepo.add(demoPOJO));
}
doOnSuccess returns Void, but you are calling a method that wraps the "action" in a returning Mono. So the demoPOJORepo#add function will never be triggered because you have broken the event chain here. The easiest fix is to just remove the wrapping Mono and return void.
public void add(DemoPOJO demoPOJO) {
demoPOJORepo.add(demoPOJO);
}
This took me way to long to find so here are some pointers when asking a question.
The names of your classes are too like each other, it was hard to follow the codeflow.
DemoPOJOService service your names are so alike so when i saw service was it the DemoPOJOService or the DemoClientService? clear names please.
There is nothing called http.POST when you wrote that i had no idea what you where talking about.
you had problems with the POST part but you posted everything, even the working GET parts, please only post code you suspect is relevant and are part of the problem.
Explain the question more clearly, what you have done, how you do it, what your application structure is and so fourth
Your endpoint urls say nothing "/DemoClient"?
How this question could have been asked to be more clear:
I have two endpoints in two routers in the same spring reactive
application.
When I do a POST request to the "/add" endpoint, this endpoint in turn
makes an a POST call using a WebClient to the same application just on
another endpoint called "/addToMap".
When this first call returns, it returns me a 200 OK status but when i
check the map (that the second endpoint is supposed to add the posted
data to) nothing gets added.
So please, next time asking a question, be clear, very clear, a lot clearer than you think. make sure your code is clear too with good variable and class names and clear url names. If you have messy names on your own computer its fine but when posting here be polite and clean up the code .It takes 5 minutes to add good names to classes and parameters so that we understand your code quicker.
take the time to read the "how to ask a good question" please.
How to ask a good question