Does ELMAH logged exceptions even when they do not bubble up to the application? I'd like to pop up a message when an exception occurs and still log the exception. Currently I've been putting everything in try catch blocks and spitting out messages, but this gets tedious.
ELMAH has been updated to support a new feature called Signaling.
This allows you to handle exceptions how you want, while still logging them to ELMAH.
try
{
int i = 5;
int j = 0;
i = i / j; //Throws exception
}
catch (Exception ex)
{
MyPersonalHandlingCode(ex);
ErrorSignal.FromCurrentContext().Raise(ex); //ELMAH Signaling
}
Re-throwing exceptions can be a bad practice as it makes it difficult to trace the flow of an application. Using Signaling is a much better approach if you intended to handle the error in some fashion and simply want to document it.
Please check out this excellent guide by DotNetSlackers on ELMAH
A filter is the cleanest way to handle this problem. Check this solution here https://stackoverflow.com/a/5936867/965935
Related
I have a fairly simple axon application that Im trying to apply some generic "catch all" exception handling logic to.
If I have a command that goes into an aggregate that throws some kind of exception e.g.
class UserAggregate {
//...
#CommandHandler()
public void on(CreateUserCommand cmd) {
Validate.notNull(cmd.getEmail(), "Email cannot be null");
//other processing
}
}
Then when I invoke this command from the Rest Controller, then the exception is far away from what I would expect
org.axonframework.commandhandling.CommandExecutionException: Email cannot be null
at org.axonframework.axonserver.connector.ErrorCode.lambda$static$10(ErrorCode.java:88)
at org.axonframework.axonserver.connector.ErrorCode.convert(ErrorCode.java:182)
at org.axonframework.axonserver.connector.command.CommandSerializer.deserialize(CommandSerializer.java:157)
at org.axonframework.axonserver.connector.command.AxonServerCommandBus$1.onNext(AxonServerCommandBus.java:313)
at org.axonframework.axonserver.connector.command.AxonServerCommandBus$1.onNext(AxonServerCommandBus.java:306)
at io.grpc.stub.ClientCalls$StreamObserverToCallListenerAdapter.onMessage(ClientCalls.java:429)
at io.grpc.ForwardingClientCallListener.onMessage(ForwardingClientCallListener.java:33)
at io.grpc.ForwardingClientCallListener.onMessage(ForwardingClientCallListener.java:33)
at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1MessagesAvailable.runInternal(ClientCallImpl.java:596)
at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1MessagesAvailable.runInContext(ClientCallImpl.java:581)
Granted the message is useful, however, this is not always a given. This can be mitigated when implementing an ExceptionHandler like so
#ExceptionHandler
public void handle(Exception exception) {
log.info("Caught Exception - {}", exception.getMessage(), exception);
}
This now gives me a stack trace pinpointing where the issue actually came from, however, this comes at the cost of having to write such an ExceptionHandler everywhere I would like to invoke this command.
Is there a more generic way to log these exceptions without having to impose the ExceptionHandler on every class issueing commands?
I would point you to the code-samples repo, where it shows a way of handling it using a MessageHandlerInterceptor.
Quoting from the repo itself:
One of the most common ways to indicate that a logical error has occurred and that Command handling failed is to throw an exception from a Command handler. However, if the exception is directly serialized there is no guarantee that the command sending side can properly deserialize the exception in question.
That is why by default Axon Framework will wrap any exception thrown inside a Command handler into a CommandExecutionException.
In short, you are going to define a MessageHandlerInterceptor responsible to try-catch the command execution logic. There you would have your centralized way of handling the CommandExecutionException.
I'm using 'Firebase Android Crash Reporting' and can't make scenario when crash happens and we don't need to manually send it.
So I should 'log' or 'report' something manually all the time I think there could be Exception?
Like 'Fabric' works. Is there any chance to achieve that?
Firebase Crash Reporting automatically reports all uncaught exceptions. So if you let exceptions "bubble up", they'll show up in Firebase automatically.
If your code already catches/handles/swallows exceptions, you can pass those exceptions on to Firebase. An example from the reference documentation:
try {
// Some code here...
} catch (Exception e) {
// Don't know what to do with this...
FirebaseCrash.log("Caught an unexpected exception while doing some work");
FirebaseCrash.report(e);
}
FirebaseCrash.log("SQL database failed to initialize");
I wrote a Windows Service that polls data on some timeintervalls and writes them in database.
But if there occures an Error writing to Database and the service stops.
I want a robust solution that goes on even if an error occures.
I put try/catch bocks around every action that is done by the service in OnStart, OnStop and Dispose but it sopped anyway.
is try/catch the correct approach?
And where do I have to put it?
Will it help to put try/catch in Main method?
Many thanks.
Try wrapping your call in a TransactionScope, this will roll back any failed changes you are trying to make and should not break on failure.
using (var scope = new TransactionScope())
{
DeleteStuff();
UpdateStuff();
scope.Complete();
}
I am using java API to interact with MQ.
When I try to get a message from an empty queue, I get exception.
Ok, but when I control it with try catch, I am expecting not prompted any error message in console.
but I get!!
try {
queue.get(getMessage, new MQGetMessageOptions());
return getMessage.readUTF();
} catch (Exception e) {
return "";
}
get in console as "MQJE001: Completion Code '2', Reason '2033'."
How can I disable this information output?
how can I check message availability or current queue size?
Thanks
First question: How can I disable this information output?
This link might help: Hide Java Output
Second question: How can I check message availability or current queue size?
MQQueue.getCurrentDepth() method will get you the current queue size. But you must note that this may not represent the correct queue depth at all times as messages could be consumed by other applications from the same queue. Actually you should not worry about queue depth. It is best practice to keep consuming messages and handle 2033 (MQJE001: MQRC_NO_MSG_AVAILABLE) exception which is thrown when there are no messages in the queue in your application.
Easiest method is using MQException.log=null line in your application.
Details bellow:
https://www.ibm.com/support/knowledgecenter/SSFKSJ_7.5.0/com.ibm.mq.dev.doc/q031000_.htm
I am having an application heavily based on QT and on a lot of third party libs. These happen to throw some exceptions in several cases.
In a native Qt App this causes the application to abort or terminate. Often the main data model is still intact as I am keeping it in pure Qt with no external data.
So I am thinking that I could also just recover by telling the user that there has occurred an error in this an that process and he should save now or even decide to continue working on the main model.
Currently the program just silently exits without even telling a story.
Sometimes it's really hard to catch all exception. If one exception accidently slips through, the following helps a lot. Inherit from QApplication and override the notify() function in the following way
bool MyApplication::notify(
QObject * receiver,
QEvent * event )
{
try
{
return QApplication::notify(receiver, event);
}
catch(...)
{
assert( !"Oops. Forgot to catch exception?" );
// may be handle exception here ...
}
return false;
}
Then replace the QApplication in your main() function by your custom class. All events and slots are issued through this function, so that all exceptions can be caught and your application becomes stable.
As stated in the Qt documentation here, Qt is currently not fully exception safe. The "Recovering from exceptions" section on that page describes the only thing which you can do in a Qt application when an exception is thrown - clean up and exit the app.
Given that you are using third party libraries which do throw exceptions, you need to catch these at the boundary between the external library and the Qt code, and handle them there - as stated in Caleb's comment. If the error must be propagated into the Qt application, this must be done either by returning an error code (if possible), or by posting an event.