I need to create a folder when it doesn't exist. In my case, the only way to do so is to capture the error and handle it to create the folder wanted.
But all i can find is
public static Observable<Boolean> folderExists(final Context context, final String targetPath, final String currentpath) {
Application application = Application.get(context);
//i browse the folder to get all the items
return browseFolderObservable(context,currentpath)
.subscribeOn(application.defaultSubscribeScheduler())
.doOnError(new Action1<Throwable>() {
#Override
public void call(Throwable throwable) {
BsSdkLog.d("Error no file found");
}
})
.map(new Func1<ArrayList<Item>, Boolean>() {
#Override
public Boolean call(ArrayList<Item> items) {
if(items.isEmpty()) {
BsSdkLog.d(" No items");
return false;
}else {
for(int i=0;i<items.size();i++)
{
Item item=items.get(i);
BsSdkLog.d(item.toString());
}
BsSdkLog.d("Right-here");
return true;
}
}
});
}
I want to call the method that i have that creates the folder when the error occurs but i don't know how to do that.
I'm new to this so i'd really appreciate the help
Thanks
The basic principe looks like this. I used the Java NIO library for testing.
The method 'createFolder' just wraps creating a folder. The test 'name' invokes the Single and checks for an Exception. If it is an IOException it will return a fallback value. You may do something different in there. You just provide a fallback single. If it is an error different from IOException, it will return the error.
#Test
void name() throws Exception {
final String TO_CREATE = "/home/sergej/Downloads/Wurstbrot";
this.createFolder(TO_CREATE)
.onErrorResumeNext(throwable -> { // handle Exception:
// Validate Exception
if (throwable instanceof IOException) {
// Return fallback
return Single.just(Paths.get("/home/sergej/Downloads/"));
}
return Single.error(throwable);
})
.test()
.await()
.assertValueCount(1)
.assertValue(path -> path.endsWith(TO_CREATE))
.assertNoErrors();
}
private Single<Path> createFolder(String p) {
return Single.defer(() -> { // may throw some IOException
Path path = Paths.get(p);
if (!Files.exists(path)) {
Path createdDirectory = Files.createDirectory(path); // will throw if already exists
return Single.just(createdDirectory);
}
// Or just return Path, because it already exists???
return Single.error(new IOException("Already exists"));
});
}
Related
I want to fetch records for newly created records in a table in postgresql as a live/continuous stream. Is it possible to use using spring r2dbc? If so what options do I have?
Thanks
You need to use pg_notify and start to listing on it. Any change that you want to see should be wrapped in simple trigger that will send message to pg_notify.
I have an example of this on my github, but long story short:
prepare function and trigger:
CREATE OR REPLACE FUNCTION notify_member_saved()
RETURNS TRIGGER
AS $$
BEGIN
PERFORM pg_notify('MEMBER_SAVED', row_to_json(NEW)::text);
RETURN NULL;
END;
$$ LANGUAGE plpgsql;
CREATE TRIGGER member_saved_trigger
AFTER INSERT OR UPDATE
ON members
FOR EACH ROW
EXECUTE PROCEDURE notify_member_saved();
In java code prepare listener
#Service
#RequiredArgsConstructor
#Slf4j
class NotificationService {
private final ConnectionFactory connectionFactory;
private final Set<NotificationTopic> watchedTopics = Collections.synchronizedSet(new HashSet<>());
#Qualifier("postgres-event-mapper")
private final ObjectMapper objectMapper;
private PostgresqlConnection connection;
#PreDestroy
private void preDestroy() {
this.getConnection().close().subscribe();
}
private PostgresqlConnection getConnection() {
if(connection == null) {
synchronized(NotificationService.class) {
if(connection == null) {
try {
connection = Mono.from(connectionFactory.create())
.cast(Wrapped.class)
.map(Wrapped::unwrap)
.cast(PostgresqlConnection.class)
.toFuture().get();
} catch(InterruptedException e) {
throw new RuntimeException(e);
} catch(ExecutionException e) {
throw new RuntimeException(e);
}
}
}
}
return this.connection;
}
public <T> Flux<T> listen(final NotificationTopic topic, final Class<T> clazz) {
if(!watchedTopics.contains(topic)) {
executeListenStatement(topic);
}
return getConnection().getNotifications()
.log("notifications")
.filter(notification -> topic.name().equals(notification.getName()) && notification.getParameter() != null)
.handle((notification, sink) -> {
final String json = notification.getParameter();
if(!StringUtils.isBlank(json)) {
try {
sink.next(objectMapper.readValue(json, clazz));
} catch(JsonProcessingException e) {
log.error(String.format("Problem deserializing an instance of [%s] " +
"with the following json: %s ", clazz.getSimpleName(), json), e);
Mono.error(new DeserializationException(topic, e));
}
}
});
}
private void executeListenStatement(final NotificationTopic topic) {
getConnection().createStatement(String.format("LISTEN \"%s\"", topic)).execute()
.doOnComplete(() -> watchedTopics.add(topic))
.subscribe();
}
public void unlisten(final NotificationTopic topic) {
if(watchedTopics.contains(topic)) {
executeUnlistenStatement(topic);
}
}
private void executeUnlistenStatement(final NotificationTopic topic) {
getConnection().createStatement(String.format("UNLISTEN \"%s\"", topic)).execute()
.doOnComplete(() -> watchedTopics.remove(topic))
.subscribe();
}
}
start listiong from controller
#GetMapping("/events")
public Flux<ServerSentEvent<Object>> listenToEvents() {
return Flux.merge(listenToDeletedItems(), listenToSavedItems())
.map(o -> ServerSentEvent.builder()
.retry(Duration.ofSeconds(4L))
.event(o.getClass().getName())
.data(o).build()
);
}
#GetMapping("/unevents")
public Mono<ResponseEntity<Void>> unlistenToEvents() {
unlistenToDeletedItems();
unlistenToSavedItems();
return Mono.just(
ResponseEntity
.status(HttpStatus.I_AM_A_TEAPOT)
.body(null)
);
}
private Flux<Member> listenToSavedItems() {
return this.notificationService.listen(MEMBER_SAVED, Member.class);
}
private void unlistenToSavedItems() {
this.notificationService.unlisten(MEMBER_SAVED);
}
but remember that if something broke then you lost pg_notify events for some time so it is for non-mission-citical solutions.
For some reason a context inside the doAfterSuccessOrError method is not available (populated) from the upstream. I've tried to access it using Mono.subscriberContext() (see the snipped). I would expect to have it present but for some reason is not. Am I doing something wrong?
public class LoggingRequestExchangeFunction implements ExchangeFilterFunction {
private final Logger log = LoggerFactory.getLogger(getClass());
#Override
public Mono<ClientResponse> filter(ClientRequest request, ExchangeFunction next) {
long start = System.currentTimeMillis();
return next.exchange(request).doAfterSuccessOrError((res, ex) -> {
Mono.subscriberContext().map((ctx -> {
log.info("doAfterSuccessOrError Context {}",ctx);
// log req/res ...
return ctx;
})).subscribe();
}).subscriberContext( ctx -> {
log.info("SubscriberContext: {}" , ctx);
return ctx;
});
}
}
Here is a log output
23:16:59.426 INFO [reactor-http-epoll-2] .p.c.LoggingRequestExchangeFunction [] SubscriberContext: Context1{nexmo-tracing-context=TracingContext{{traceId=f04961da-933a-4d1d-85d5-3bea2c47432f, clientIp=N/A}}}
23:16:59.589 INFO [reactor-http-epoll-2] .p.c.LoggingRequestExchangeFunction [] doAfterSuccessOrError Context Context0{}
The reason is that you create a new Mono inside doAfterSuccessOrError which is independent from the original reactor chain since you subscribe to it separately.
If you just want to log something inside, your alternative is to use doOnEach operator which beside the signal type gives you access to the context as well.
Mono.just("hello")
.doOnEach((signal) ->
{
if (signal.isOnError() || signal.isOnComplete())
{
Context ctx = signal.getContext();
log.info("doAfterSuccessOrError Context {}",ctx);
// log req/res ...
}
})
.subscriberContext( ctx -> {
log.info("SubscriberContext: {}" , ctx);
return ctx;
})
.subscribe();
I have written a common validator as part of Ninject interceptor. My requirement is that I have to return a response object, just like how any service method in my project returns, for consistency sake. By returning a response object also helps me to send back an appropriate validation message when the validator fails. How do I do that in the interceptor? I understood that the Intercept() returns nothing. I tried throwing an exception but I don't know where to catch it. Can someone help me?
public void Intercept(IInvocation invocation)
{
var validationFails = false;
if (validationFails)
{
// return an object
// response.ErrorMessage = "Validation Error"
// Or throw exception, but where should I catch it
throw new Exception(statusMessage);
}
else
{
invocation.Proceed();
}
}
Assign the ReturnValue and don't call Proceed when validation fails.
public class MyRequestHandler
{
Response ProcessRequest(string input) { return new Response(); }
}
public MyValidationInterceptor : IInterceptor
{
public void Intercept( IInvocation invocation )
{
if (NeedsValidation(invocation.Method) &&
!IsValidRequest((string)invocation.Arguments[0]))
{
invocation.ReturnValue =
new Response { ErrorMessage = "Validation Error" };
return;
}
invocation.Proceed();
}
}
I had to hook up my interceptor to business layer methods, instead of service methods, and am able to return proper return value as part of my response.
I need errors to be logged in the same way across a large number of function calls. Here I want errors from foo.create(...) and File.new_tmp(...) to be logged by handle_error(...).
// compile with `valac --pkg gio-2.0 main.vala`
void log_error(Error e) {
// error logging here
}
void main() {
var foo = File.new_for_path("foo");
try {
foo.create(FileCreateFlags.NONE);
} catch (Error e) {
log_error(e);
}
FileIOStream tmp_stream;
try {
File.new_tmp(null, out tmp_stream);
} catch (Error e) {
log_error(e);
}
}
(Yes, main should continue with the FileIOStream stuff if foo.create fails, which is why they're in separate try/catch blocks.)
I want to factor out the use of try {...} catch (Error e) {log_error(e);} into a function like so:
delegate void Action();
void log_error(global::Action action) {
try {
action();
} catch (Error e) {
// error logging here
}
}
void main() {
var foo = File.new_for_path("foo");
log_error(() => foo.create(FileCreateFlags.NONE));
FileIOStream tmp_stream;
log_error(() => File.new_tmp(null, out tmp_stream));
}
But valac gives the warning unhandled error 'GLib.IOError' because you can't seem to catch errors thrown within a closure, nor can I just rewrite log_error(...) as a #define macro as vala doesn't support them. So what can I do?
You can catch exceptions thrown in closures, you just need to have the delegate throw the exception. What you want is probably something like this:
public delegate T? Action<T> () throws GLib.Error;
T? log_error<T> (global::Action<T> func) {
try {
return func ();
} catch (GLib.Error e) {
// error logging here
return null;
}
}
void main () {
var foo = File.new_for_path("foo");
log_error<GLib.FileOutputStream> (() => foo.create (FileCreateFlags.NONE));
FileIOStream? tmp_stream = null;
GLib.File? f = log_error<GLib.File> (() => File.new_tmp (null, out tmp_stream));
}
Note that I've made it a generic so you can actually use a return value. If you want it should be trivial to remove the generic type argument and just return void, though you'll lose some flexivility.
I'm using Struts2. I have two web forms that have the same code. I would like to eliminate one form. Here is the structure of my Struts project.
\Web Pages
form.jsp
\WEB-INF
\Content
error.jsp
form.jsp
success.jsp
\Source Packages
\action
MyAction.java
MyAction.java
package action;
import com.opensymphony.xwork2.ActionSupport;
import org.apache.struts2.convention.annotation.*;
public class MyAction extends ActionSupport {
#Action(value = "foo", results = {
#Result(name = "input", location = "form.jsp"),
#Result(name = "success", location = "success.jsp"),
#Result(name = "error", location = "error.jsp")
})
public String execute() throws Exception {
if (user.length() == 1) {
return "success";
} else {
return "error";
}
}
private String user = "";
public void validate() {
if (user.length() == 0) {
addFieldError("user", getText("user required"));
}
}
public String getUser() {
return user;
}
public void setUser(String user) {
this.user = user;
}
}
I tried to eliminate form.jsp under \Web Pages by adding a new action method to MyAction.java.
#Action(value="bar", results = {
#Result(name = "success", location = "form.jsp"),
})
public String another() {
return "success";
}
But I got the following error when I go to http : //localhost .../bar.action
HTTP Status 404 - No result defined for action action.MyAction and result input
Your MyAction has an implementation of validate(), which means it is validation aware.
What's happening is that you're calling another, but validate() is kicking in (as it's in the interceptor stack). Validation is failing, and therefore sending to INPUT result, which is not defined in another.
You should
Add #SkipValidation to the another method if you don't want validation there
Add the INPUT result to another() if you want a default input result
On a more general note, when you get that kind of error (No result defined for action X and result input) it usually means you're either having validation errors, parameter population errors (eg: an exception in preparable).