UpdateById method in Spring Reactive Mongo Router Handler - spring

Question

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.

Answer 1

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));
}

Answer 2

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.