How do I perform operations that have side effects in response to a stream being empty? For example, to handle the case where a client sends an empty body, and we read it with .bodyToMono(...).
See for example:
public Mono<ServerResponse> createEventDetails(ServerRequest request) {
return request.principal().flatMap(principal -> {
UserProfile userProfile = (UserProfile) ((UsernamePasswordAuthenticationToken) principal).getCredentials();
final String id = request.pathVariable("id");
final UUID eventId = UUID.fromString(id);
return request.bodyToMono(CreateEventDetailsRequest.class)
.map(body -> new CreateEventDetailsCommand(eventId, userProfile, body.getObjectId(), body.getDocumentUrls()))
.flatMap(command -> {
createEventDetailsCommandHandler.handle(command);
return ServerResponse
.created(URI.create(eventId.toString()))
.body(BodyInserters.fromObject(new CreateEventDetailsResponse(eventId)));
})
.switchIfEmpty(ServerResponse.badRequest().syncBody(new Error("missing request body for event id: " + id)))
.map(response -> {
LOG.error("POST createEventDetails: missing request body for event id: " + id);
return response;
});
});
}
This returns the desired 400 response in the case that the client omits the request body, but the log message is always printed, even for successful requests.
My best guess as to why this occurs, is that .switchIfEmpty(...).map(...) is executed as one unit by the framework, and then the result ignored.
How do I handle this case?
There are a few ways to do this. In the case above you can just add the logging to the switch
e.g.
.switchIfEmpty(ServerResponse.badRequest().syncBody(new Error("missing request body for event id: " + id))
.doOnNext(errorResponse -> LOG.error("POST createEventDetails: missing request body for event id: " + id)
)
another approach could be sending an Error signal back and in your handler catch and log it.
You can have a look here https://www.baeldung.com/spring-webflux-errors
Some light reading can be found here https://docs.spring.io/spring-framework/docs/5.0.0.BUILD-SNAPSHOT/javadoc-api/org/springframework/web/server/WebHandler.html
Use HttpWebHandlerAdapter to adapt a WebHandler to an HttpHandler. The
WebHttpHandlerBuilder provides a convenient way to do that while also
optionally configuring one or more filters and/or exception handlers.
You can view a sample handler in ResponseStatusExceptionHandler
Related
I created a filter to log some important data from the request and response...
#Override
public Mono<ClientResponse> filter(ClientRequest request, ExchangeFunction next) {
URI uri = request.url();
HttpMethod method = request.method();
return next.exchange(request).onErrorResume(err -> {
writeToFile(method, uri, 500, "", true);
return Mono.error(err);
}).flatMap((response) -> {
return response.bodyToMono(String.class).flatMap(body -> {
writeToFile(method, uri, response.rawStatusCode(), body, false);
return Mono.just(response);
});
});
}
The idea of this filter is to register some data and let the rest work exactly the same.
Expected: This was my attempt to keep the rest of the code untouched and just include a filter to store some data apart from the normal flow.
Actual: It works, except when the real code calls bodyToMono, it returns null
At some point of the normal flow, I am doing something similar to this:
return client.get().uri(...).exchangeToMono((response) -> {
return response.bodyToMono(MyObject.class);
})
It works flawlessly when I remove the filter.
So I discovered I can't call bodyToMono twice the way I am using probably because the first call is consuming the body and then it is empty in the second call.
I'm writing a web api using PostgreSQL and am checking database constraints as part of the validation process, but I also have a global exception filter as a fallback in case something gets by when saving. My problem is that the exception doesn't seem to have any message that I can present to the client without some processing. The added image is of the PostgresException data from a breakpoint. For example, in this case I would want something along the lines of "Asset Number x already exists" or just "Asset Number must be unique". Is this something that can be configured somewhere? The place that makes the most sense is at the constraint creation code, but I couldn't find an option to do so.
modelBuilder.Entity<AssetItem>().HasIndex(item => new { item.AssetNumber }).IsUnique();
public class DbExceptionFilter : IExceptionFilter
{
private const string UNIQUE_EXCEPTION = "23505";
public async void OnException(ExceptionContext context)
{
var exceptionType = context.Exception.InnerException.GetType().FullName;
if (exceptionType == "Npgsql.PostgresException")
{
var pgException = (PostgresException) context.Exception.InnerException;
switch(pgException.SqlState)
{
case UNIQUE_EXCEPTION:
var error = new {error = "Unique Error Here"};
await WriteJsonErrorResponse(context.HttpContext.Response, HttpStatusCode.BadRequest, error);
return;
}
}
else
{
var error = new { error = "Unexpected Server Error"};
await WriteJsonErrorResponse(context.HttpContext.Response, HttpStatusCode.InternalServerError, error);
return;
}
}
private async Task WriteJsonErrorResponse(HttpResponse response, HttpStatusCode statusCode, dynamic error)
{
response.ContentType = "application/json";
response.StatusCode = (int) statusCode;
await response.Body.WriteAsync(Encoding.ASCII.GetBytes(JsonConvert.SerializeObject(error)));
}
}
The closest thing to a user-readable message that PostgreSQL provides is the message text exposed on PostgresException.
However, as a general rule it is not a good idea to expose database errors directly to users (including web API users): these are intended to the application directly interacting with the database (i.e. your application). These messages generally don't mean much to the users of your API, and more importantly they leak potentially sensitive information about your database schema and are therefore not secure. It's especially problematic to dump/serialize the entire exception to the user as you seem to be doing (with JsonConvert.SerializeObject).
The best practice here would be to identify legitimate database exceptions that the user may trigger, intercept these and return and appropriately-worded message of your own (e.g. "A user with that name already exists").
As a side note, to identify PostgresException, rather than getting the name of the exception and comparing to that, you can simply use C# pattern matching:
if (context.Exception.InnerException is PostgresException postgresException)
{
// ...
}
I am just starting to use jhipster 5 and angular 5. I have a form and in that form in addition to few regular fields, I have a file input.
I could not find any documentation on how to file in jhipster.
EDIT 1:
I could somehow managed to upload file and send to server. Below is my server method to handle the form submission.
#PostMapping("/email-jobs")
#Timed
public ResponseEntity<EmailJobDTO> createEmailJob(MultipartFile file, #Valid #RequestBody EmailJobDTO emailJobDTO) throws URISyntaxException {
log.debug("REST request to save EmailJob : {}", emailJobDTO);
if (emailJobDTO.getId() != null) {
throw new BadRequestAlertException("A new emailJob cannot already have an ID", ENTITY_NAME, "idexists");
}
System.out.println(file.getName() + " File Name ");
EmailJobDTO result = emailJobService.save(emailJobDTO);
return ResponseEntity.created(new URI("/api/email-jobs/" + result.getId()))
.headers(HeaderUtil.createEntityCreationAlert(ENTITY_NAME, result.getId().toString()))
.body(result);
}
Here i get following exception,
Unsupported Media Type: Content type 'multipart/form-data;boundary=----WebKitFormBoundary73sdwuJtdeRk6xsO;charset=UTF-8' not supported
If I remove #RequestBody from method signature then I dont get above exception but then I start getting 400 bad request exception saying my form fields can not be null.
You must define MultipartFile is #RequestParam and declare produces = MediaType.APPLICATION_JSON_VALUE in post mapping, like:
#PostMapping("/email-jobs", produces = MediaType.APPLICATION_JSON_VALUE)
Client side, you can try send request as this:
Upload.upload({
url: 'api/path',
data: {
file: yourdatafile
},
headers: {'Content-Type': 'multipart/form-data'}
}).progress(function (evt) {
// handle progress
}).success(function (data, status, headers, config) {
// handle success
});
Instead of uploading a file, create a field type as a BLOB and then in your business logic, make a file if u need or else do your.
Background
Notification service has a Notify method which is invoked when an event occurs, so here Im creating the FloorActor and sending the message consisting data and post url to the Actor.
public class NotificationService
{
//HttpClient client = new HttpClient();
ActorSystem notificationSystem = ActorSystem.Create("NotificationSystem");
public void Notify(int clientID, FloorEventData data)
{
try
{
string postUrl = "http://localhost:6001";
FloorData floorData = new FloorData() { Data = data,PostURL=postUrl };
//This commented line of code post data and listener gets the POST request
//client.PostAsJsonAsync<FloorEventData>(postUrl, data);
//Create Floor Actor
var floorActor = notificationSystem.ActorOf<FloorActor>("floorActor");
floorActor.Tell(data);
}
catch (Exception exception)
{
//Log exception
}
}
}
ReceiveAsync method of the Floor Actor data just posts the event data to the specified URL.Framework used to implement Actor Model :Akka.Net
public class FloorActor : ReceiveActor
{
HttpClient client = new HttpClient();
public FloorActor()
{
ReceiveAsync<FloorData>(floorActor => client.PostAsJsonAsync<FloorEventData>(floorActor.PostURL, floorActor.Data));
}
}
Issue-
When I debugged the issue the code flow works as expected:-
1) When event occurs Notify method is invoked
2) Notify method creates the Floor Actor and sends the data
3) Floor Actor's ReceiveAsync method is called and the line of code is executed without any errors or exceptions.But the POST listener, doesn't get the POST data request, so not sure what is happening ?
Tried POST data directly from the Notify method its works, the listener gets the POST request.You can see this code snippet commented above in the Notify method.
So when I try to POST data from my Actor's Receive method, the Http listener does not get the request and there is no errors or exception.
Please let me know if I have to change anything?
ActorSystem should be treated as a singleton for your entire system. So put that instance in a static somewhere and reference it from there.
Also try to await on client.PostAsJsonAsync
In the Re-usability use-case project with RedisMQ there is a SMessageService which has the following handler.
SMessageService :Service{
public object Any(EmailMessage request)
{
var sw = Stopwatch.StartNew();
Db.InsertAll(Email.Process(request));
return new SMessageResponse { TimeTakenMs = sw.ElapsedMilliseconds };
}...
}
When the services returns, it puts the message in the mq:SMessageResponse.inq list.
My questions is if I return null instead of new SMessageResponse{...}, a message is put in the mq:EmailMessage.outq list, what is the reason for this?
Also, if I don't want to return a response at all, how would I do this or is this bad practice in the area of messaging?. In other words, I always need to have a log of what has happened.