I am building a NativeScript mobile app and among other things I am capturing for analytics purposes, I need to capture "app crashes" possibly with errors/reasons it crashed.
I came across this SO post but there it was in the response of a question on how not to let the app crash. Following was suggested to catch crash events:
var application = require("application");
application.on(application.uncaughtErrorEvent, function (args) {
if (args.android) {
// For Android applications, args.android is an NativeScriptError.
console.log("NativeScriptError: " + args.android);
} else if (args.ios) {
// For iOS applications, args.ios is NativeScriptError.
console.log("NativeScriptError: " + args.ios);
}
});
If I go by the above then I have the following questions. Would appreciate if somebody can confirm if this means every-time the app is crashing it will generate this application.uncaughtErrorEvent event? Can I rely on it?
If it is true then maybe I can make a REST call to my backend and store date, time and whatever is in args.android or args.ios.
If above is not the correct way then can somebody please help me on how to go about doing this?
Any help is highly appreciated. Thank you!
The application.onUncaughtError will be hit probably 95-98% of the time during a crash; it is pretty reliable. I have seen the app crash without any notice at all it just goes poof, but I'm not sure any reporting system can handle that one.
The way I do it is during the app startup I register a couple things:
I create a global.error function; this is used for anything (like try/catch, promise/catch) that needs to send the errors through to be logged remotely. So anywhere in my codebase I can do a global.error(theError); and it will be handled; this way I do NOT have to worry about trying to load or require things while an error is taking place, as that can cause other errors.
I use the onUncaughtError event to catch anything that is not normally caught, and then notify the user that an error has occurred and quit the app. (in this case, trying to recover is not recommended as you have no idea where the error was thrown from...)
If I use a worker thread, When I startup a worker I register the worker.onerror to forward its data to the main threads global.error function AND I have a specific message from the workers' version of the global.error that sends the error back to the primary thread. This way if the worker itself calls global.error that message is passed back to the main thread and then to the global.error on the main thread which handles everything properly.
This technique allows me to catch pretty much all errors that can occur. The main global.error function and the onUncaughtError both use a simple reporting library that I built that reports all the data back to one of my servers, IF the device is online. If the device is offline, it can optionally save the data to a reporting file to be uploaded later; or just ignore it.
It also has safety checks to verify the error isn't a network error (we don't want the error reporting to go into a loop, i.e. trying to report the error causes an error, which then tries to report the error; so in the event it is a certain type of network error; it will ignore those. )
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[Clarified]
I'm writing my first Laravel app using Vue components; it is a CRUD. I know how to report significant problems to laravel.log via the Log::error("There is an error") technique but that's only useful while I'm in the PHP code; as far as I can figure out, there's no way to write to laravel.log from within a Vue component. (Correct me if I'm wrong!!)
This raises the question of how I should report an error in a Vue component in a Laravel app. I know about console.log(), Debugger for Chrome, and Devtools and those are fine for development. But what about errors that might reasonably happen in production? Clearly, user errors like bad input on a form needs to be dealt with by notifying the user and letting the user correct their input but some errors are beyond the user's scope. For example, it's not hard to imagine my Vue component failing to access the database because it is down for some reason. Shouldn't that kind of problem be written to a log so that whoever monitors production apps can deal with it?
How would a professional app deal with that kind of situation?
My initial inclination is just to write it to laravel.log if possible but that may be either impossible or be considered a bad approach. I'd be curious to know what experienced Laravel developers do in such situations. Maybe automatically sending a text to a support person would be a better approach. I'm really not sure how this should be handled in a modern professional way.
In any case, whoever is responsible for situations beyond the user's control needs to be told somehow so they can begin the steps that would be necessary to fix the problem. Furthermore, this person needs to be given sufficient details of what happened to be able to solve the problem. I expect that would include things like stacktraces, error codes, etc. I wouldn't want to send all of that as a stream of texts, I'd want it all to be accessible in a log of some kind. Then, you simply notify the support person that there is a problem of such-and-such severity which occurred at such-and-such a time and remind them where to find the details.
My approach may be dated though and newer, better alternatives may exist. Those are what I'm looking for with my question.
I can give a general purpose answer for your question.
React introduced the concept of ErrorBoundary,
Error boundaries are React components that catch JavaScript errors anywhere in their child component tree, log those errors, and display a fallback UI instead of the component tree that crashed.
Using Error Boundary in Vue
use vue-error-boundary
This simple code of handleError method shows ErrorBoundary receiving a callback function through the on-error prop.
<template>
<ErrorBoundary :on-error="handleError">...</ErrorBoundary>
<template>
<script>
// ...
methods: {
handleError (err, vm, info) {
// do something
}
}
// ...
</script>
read the docs for the npm module to know more.
while handling errors, you can pass the errors to a link to your production site.
eg. /logging so it would be like https://www.example.com/logging, and post the errors in a format eg Date: Error File: Error Message.
You can even use authentication tokens along this link (though no one would use it as it would be frontend errors everyone can see it at console).
Then use routes to log those errors to laravel logs.
I have problem with launching Google-Cast application similar to sample CastHelloText-chrome. I slightly modified example code for my specific purposes. The goal for creating this application is to send and show image data directly in Chromecast device.
Particularly the difference between official sample and my code is in message format and its content, sent by sender application. Sender application took png image coded by base64 and send through message bus with custom namespace. Receiver application get this message and use this as data source for html object <img>.
Error appears when I do this steps:
Reload sender page, checking console if any device found.
Send the form by just pushing enter on input box (text is ignored).
Now a popup from Chromecast extension shows. Next there are two scenarios:
3a) I confirm casting to device by choosing one from the list, then I get this error message in console:
onError: {"code":"channel_error","description":"Error: Timeout","details":null}
3b) I just click somewhere else, I get this error:
onError: {"code":"cancel","description":"User closed popup menu","details":null}
Both of errors are caused by calling function chrome.cast.requestSession in chromehellotext.html at line 161, but what's really wrong I don't know.
When I step sender script I realize that function sessionListener is never called. I know that something go wrong when code try to call chrome.cast.requestSession, where described error raises. So I need help if I missed about right way to use Google-Cast API or If this problem has something to do with networking issues.
Receiver application is registered on Google Cast SDK Developer Console and I'm testing on registered device with some serial number. I'm using Google Chrome in version 42.0.2300.2 canary (64-bit) and Chrome version 40.0.2214.111 (current stable I suppose). For testing I also tried to turn off Windows Firewall entirely but with no luck.
Edit:
There were some syntactic errors that caused error message described above.
It seems like you are trying to use the data/control channel to send an image; please don't do that; that channel is not meant to be used for large data communications; in fact it cannot send anything which approaches or exceeds 64k. If your goal is to send images from your local machine, you would need to run a local web server on your local machine and serve images through the web server.
For and easiest tutorial you can have a look to this tutorial.
It is well explained in this tutorial.
Chromecast Sender application
There is no need to maintain session by yourself.
just add button and enjoy casting
mCastManager.addMediaRouterButton(mediaRoutebtn);
I found a source of my problem. There was something wrong in receiver code - syntactic and runtime errors, so I must admit that my code wasn't functional. Now its working in terms of launching application and getting session.
Unfortunate thing is that the error message generated by Chromecast extension didn't match the actual error - at least it was a bit confusing when I didn't know what's really happening on receiver side without ability to debug the code.
I want to turn off the display at a particular point using DisplayRequest.RequestRelease but im getting various exception. When i tried for desktop im getting "Arithmetic result exceeded 32 bits" error. In phone im getting system.excecutionEngine exception. I need to know the correct usage of this function.
There are two things wrong here.
DisplayRequest.RequestRelease is used to release a previous request to keep the display alive. If you haven't called RequestActive before, then it won't work and will throw the exception.
If you are doing it to release a previous call, then it's possible that things are going wrong after a suspend operation, because you may have inadvertently called RequestRelease in your OnNavigatingFrom member. Please see my blog for full details at Most of my Windows 8 Apps are broken. Yours probably are too
I have run into an Interesting scenario. Its also present here by someone on msdn forums
When I launch my application, if I lock the screen or if a call comes at that time and on resume after unlocking or disconnecting the call in respective scenarios, the application crashes throwing 0x8000ffff error. This I have observed also happens when an emailcomposetask is open from my application.
Previously I thought that it was because I was not handling Obscured and Unobscured. But now that I am handling them, still I am receiving the same case. I have observed that many other applications also crash but there are some applications like Facebook and Twitter which are able to handle it. Has any one faced this same situation? Can you please provide me a fix for this?
Am I doing anything wrong?
also note that I have changed my default loading page. Its not mainPage.xaml but xyz.xaml, where I am checking for tokens and redirecting user to mainPage automatically without any button click.
Edit : Added StackTrace
at Microsoft.Phone.Execution.NativeEmInterop.NotifyFullObscurityChanged(Boolean isObscured)
at Microsoft.Phone.Shell.PhoneApplicationService.OnFullObscurityChanged(Object sender, LockStateChangeEventArgs e)
at Microsoft.Phone.Shell.Interop.ShellPageManager.ShellPageCallback_OnLockStateChange(Object source, LockStateChangeEventArgs e)
at Microsoft.Phone.Shell.Interop.ShellPageCallback.FireOnLockStateChange(Boolean fLocked)`
This mainly happens because of the code in OnNavigatedTo() and Page_Loaded() event handlers. Place break points and check for the issues in those two methods.
When an app is resumed in the cases you mentioned, these two methods are called in the same order.
Hope this solves your problem.
Update based on your comments:
There you are. You are clearing the entire Navigation history, and hence it dont know where to go now(even the current page is removed).
My suggestion is, Move your back history removal code from OnNavigated to the Page_Loaded event.
Just want to check I have not missed anything obvious. There is no way to Navigate the user to a "ooops something bad has happened" page from the UnhandledException handler is there?
What is everyone else doing
I know I can "handle" the error and popup up messagebox but I would prefer a whole page offering them the oppurtunity to file a bug report.
The samples I have seen simply set the RootFrame directly but I have seen that just makes for a messy UI with what looks like a Page displayed on top of another page
TIA
Pat
If you get an UnhandledException it occurs while your applicaiton is about to be shut down. The best you can do in this situation is warn the user that something went wrong (using a messagebox or similar) but be prepared that this may not be displayed to the user for long, depending on the actual exception.
Rather than try and continue executing application functionality when an unhandled exception occurs, simply save the details of the exception. Then, when the application is next started, display a message to the user to indicate that "the last time that app ran there was a problem". You can also use this opportunity to send exception details to yourself/ your web reporting service so you can analyse the issues and fix/prevent them in a future version.
You can call RootFrame.Navigate(your errorPage) to navigate to your custom error page in the UnhandledException handler.
Basically, using a custom MessageBox to show a nice easy-going error info and providing an button to send bug report is very common. And this article is MSDN pointed out that errorinfo not be a separate page in best practice.