I'm trying to set up a hook to catch all exceptions and errors thrown from my Dancer application ( an API ) and pass them to a function that sets the HTTP status code and returns the hash ( serialized as JSON ).
Everything works fine when I use try/catch, but when I move it to a hook it runs the code but the response is formed using the default error mechanism instead of my function.
This is the hook I'm using:
# Handle errors
hook on_handler_exception => sub {
my $e = shift;
debug "ON HANDLER EXCEPTION";
return API::Exception->handle($e); # sets status code and returns hash depending on the exception
};
I also tried using halt instead of return to stop any further processing of the exception but it didn't alter anything.
How would I accomplish this with Dancer? Thanks.
use the "on_route_exception" hook instead ...
hook on_route_exception => sub
{
my ( $exception ) = #_;
error( $exception );
status( 'error' );
halt( { errors => [ { message => 'An unhandled exception occurred', code => 0 } ] } );
};
Have a look at the code of Dancer::Error.
I think something like
my $content = Dancer::Engine->engine("template")->apply_renderer($template_name, $ops);
return Dancer::Response->new(
status => $self->code,
headers => ['Content-Type' => 'text/html'],
content => $content);
from the _render_html method could help you.
Related
Example:
hook on_route_exception => sub {
# This code is not executed
}
hook on_handler_exception => sub {
# This code is not executed
}
hook after => sub {
# This code is not executed
}
hook after_error_render => sub {
# This code is not executed
}
hook before => sub {
if ($some_condition) {
halt("Unauthorized");
# This code is not executed :
do_stuff();
}
};
get '/' => sub {
"hello there";
};
I can find this piece of documentation:
Thus, any code after a halt is ignored, until the end of the route.
But hooks are after the end of route, so should not be ignored. Should be?
Why hooks are ignored too?
I would think that the reason is that the processing was halted. The
halt("Unauthorized");
would essentially return that content in the response object and no further events are required. The halt effectively halted all processing for that request/response.
That is a guess based on how it is behaving and the description.
A closer look at :https://metacpan.org/release/BIGPRESH/Dancer-1.3513/source/lib/Dancer.pm#L156
shows that after the Response Content is set to "Unauthorized" it calls:
Dancer::Continuation::Halted->new->throw
which dies:
https://metacpan.org/release/BIGPRESH/Dancer-1.3513/source/lib/Dancer/Continuation.pm#L14
sub throw { die shift }
At least that's how I read that code. Since it dies there is nothing else to do.
Likely a deliberate design decision based on the intention to halt.
I am trying to create a slack application in Perl with mojolicious and I am having the following use case:
Slack sends a request to my API from a slash command and needs a response in a 3 seconds timeframe. However, Slack also gives me the opportunity to send up to 5 more responses in a 30 minute timeframe but still needs an initial response in 3 seconds (it just sends a "late_response_url" in the initial call back so that I could POST something to that url later on). In my case I would like to send an initial response to slack to inform the user that the operation is "running" and after a while send the actual outcome of my slow function to Slack.
Currently, I can do this by spawning a second process using fork() and using one process to respond imidiately as Slack dictates and the second to do the rest of the work and respond later on.
I am trying to do this with Mojolicious' subprocesses to avoid using fork(). However I can't find a way to get this to work....
a sample code of what I am already doing with fork is like this:
sub withpath
{
my $c = shift;
my $user = $c->param('user_name');
my $response_body = {
response_type => "ephemeral",
text => "Running for $user:",
attachments => [
{ text => 'analyze' },
],
};
my $pid = fork();
if($pid != 0){
$c->render( json => $response_body );
}else{
$output = do_time_consuming_things()
$response_body = {
response_type => "in-channel",
text => "Result for $user:",
attachments => [
{ text => $output },
],
};
my $ua = Mojo::UserAgent->new;
my $tx = $ua->post(
$response_url,
{ Accept => '*/*' },
json => $response_body,
);
if( my $res = $tx->success )
{
print "\n success \n";
}
else
{
my $err = $tx->error;
print "$err->{code} response: $err->{message}\n" if $err->{code};
print "Connection error: $err->{message}\n";
}
}
}
So the problem is that no matter how I tried I couldn't replicate the exact same code with Mojolicious' subproccesses. Any ideas?
Thanks in advance!
Actually I just found a solution to my problem!
So here is my solution:
my $c = shift; #receive request
my $user = $c->param('user_name'); #get parameters
my $response_url = $c->param('response_url');
my $text = $c->param('text');
my $response_body = { #create the imidiate response that Slack is waiting for
response_type => "ephemeral",
text => "Running for $user:",
attachments => [
{ text => 'analyze' },
],
};
my $subprocess = Mojo::IOLoop::Subprocess->new; #create the subprocesses
$subprocess->run(
sub {do_time_consuming_things($user,$response_url,$text)}, #this callback is the
#actuall subprocess that will run in background and contains the POST request
#from my "fork" code (with the output) that should send a late response to Slack
sub {# this is a dummy subprocess doing nothing as this is needed by Mojo.
my ($subprocess, $err, #results) = #_;
say $err if $err;
say "\n\nok\n\n";
}
);
#and here is the actual imidiate response outside of the subprocesses in order
#to avoid making the server wait for the subprocess to finish before responding!
$c->render( json => $response_body );
So I actually simply had to put my code of do_time_consuming_things in the first callback (in order for it to run as a subprocess) and use the second callback (that is actually linked to the parent process) as a dummy one and keep my "imidiate" response in the main body of the whole function instead of putting it inside one of the subprocesses. See code comments for more information!
I am using slim framework 3 . I am new to this framework. I am working on catching the errors and returning the custom JSON error and message.
I used this code to catch notFoundHandler error :
$container['notFoundHandler'] = function ($c) {
return function ($request, $response) use ($c) {
return $c['response']
->withStatus(404)
->withHeader('Content-Type', 'application/json')
->write('Page not found');
};
};
But I am able to catch the normal syntax error.
It is showing Warning: fwrite() expects parameter 2 to be string, array given in X-api\controllers\Products.php on line 42
Instead of this message, I want my custom error to handle syntax error reporting.
I used this also,
$container['phpErrorHandler'] = function ($c) {
return function ($request, $response, $exception) use ($c) {
//Format of exception to return
$data = [
'message' => "hello"
];
return $container->get('response')->withStatus($response->getStatus())
->withHeader('Content-Type', 'application/json')
->write(json_encode($data));
};
};
But not working for me.
The default error handler can also include detailed error diagnostic information. To enable this you need to set the displayErrorDetails setting to true:
$configuration = [
'settings' => [
'displayErrorDetails' => true,
],
];
$c = new \Slim\Container($configuration);
$app = new \Slim\App($c);
Note this is not appropriate for production applications, since it may reveal some details you would want not to reveal. You can find more in Slim docs.
EDIT
If you need to handle parseErrors, then you need to define phpErrorHandler in your container, just like you did define notFoundHandler.
$container['phpErrorHandler'] = function ($container) {
return function ($request, $response, $error) use ($container) {
return $container['response']
->withStatus(500)
->withHeader('Content-Type', 'text/html')
->write('Something went wrong!');
};
};
Note: this will work with PHP7+ only, because in older versions parseErrors cannot be catched.
I have used this short of code in my dependencies.php
$container['errorHandler'] = function ($c) {
return function ($request, $response) use ($c) {
$data = [
'message' => "Syntex error"
];
return $c['response']
->withStatus(200)
->withHeader('Content-Type', 'application/json')
->write(json_encode($data));
};
};
set_error_handler(function ($severity, $message, $file, $line) {
if (!(error_reporting() & $severity)) {
// This error code is not included in error_reporting, so ignore it
return;
}
throw new \ErrorException($message, 0, $severity, $file, $line);
});
Now its working for me.
I have a small slim 3 app, and when I throw an exception slim simply shows the generic error message:
Slim Application Error
A website error has occurred. Sorry for the temporary inconvenience.
In slim 2 you can do something like this to turn on debug mode giving you backtraces etc:
$app->config('debug', true);
In slim 3 there doesn't seem to be one. Additionally, it seems to be overriding my exception and error handlers.
How can I get slim to spit out errors, or at least to call my error handlers (Which pipe the output to kint for debug information)
Looking through the source, it's possible to initialize slim 3 with error display like so:
$app = new \Slim\App(['settings' => ['displayErrorDetails' => true]]);
I'm not sure if it's possible to change this setting after the fact without replacing the errorHandler altogether.
To show full stack trace on default exception handler use what j-v said.
If you want to handle exceptions in Slim yourself then you need to override Slim's default exception handler as it will be used before your "not in Slim" error handler:
$app = new \Slim\App();
$container = $app->getContainer();
$container['errorHandler'] = function(ServerRequestInterface $request, ResponseInterface $response, Exception $exception) {
//Handle exception here
}
Error handling is rather well documented: Official Docs
$app = new \Slim\App();
$c = $app->getContainer();
$c['errorHandler'] = function ($c) {
return function ($request, $response, $exception) use ($c) {
return $c['response']->withStatus(500)
->withHeader('Content-Type', 'text/html')
->write('Something went wrong!');
};
};
Error handling is best solution to this. You can do something like to see Error Trace
$app = new \Slim\App();
$container = $app->getContainer();
$container['phpErrorHandler'] = $container['errorHandler'] = function ($c) {
return function ($request, $response, $exception) use ($c) {
return $c['response']->withStatus(500)
->withHeader('Content-Type', 'text/html')
->write('Something went wrong!<br><br>' .
nl2br($error->getTraceAsString()));
};
};
Make displayErrorDetails->true.
You will find cause of error.
$config = ['settings' => [
'addContentLengthHeader' => true,
'displayErrorDetails' => true
]];
$app = new \Slim\App($config)
in my stage server I would like to activate the debug so the clients can find errors for themselves before the app goes to the production server.
BUT I only want the first part of the message, not the Request, or the Session Data.
For example: Couldn't render template "templates/home.tt2: file error - templates/inc/heater: not found".
The message is enough for me and for my client to see that the "header" call is misspelled.
The Request has a lot of irrelevant information for the client, but also has A LOT of internal developing information that should be hidden all the time!!
Regards
What you want is to override Catalyst's dump_these method. This returns a list of things to display on Catalyst's error debugging page.
The default implementation looks like:
sub dump_these {
my $c = shift;
[ Request => $c->req ],
[ Response => $c->res ],
[ Stash => $c->stash ],
[ Config => $c->config ];
}
but you can make it more restrictive, for example
sub dump_these {
my $c = shift;
return [ Apology => "We're sorry that you encountered a problem" ],
[ Response => substr($c->res->body, 0, 512) ];
}
You would define dump_these in your app's main module -- the one where you use Catalyst.
I had a similar problem that I solved by overriding the Catalyst method log_request_parameters.
Something like this (as #mob said, put it in your main module):
sub log_request_parameters {
my $c = shift;
my %all_params = #_;
my $copy = Clone::clone(\%all_params); # don't change the 'real' request params
# Then, do anything you want to only print what matters to you,
# for example, to hide some POST parameters:
my $body = $copy->{body} || {};
foreach my $key (keys %$body) {
$body->{$key} = '****' if $key =~ /password/;
}
return $c->SUPER::log_request_parameters( %$copy );
}
But you could also simply return at the beginning, if you don't want any GET/POST parameters displayed.
Well, I didn't think of the more obvious solution, in your case: you could simply set your log level to something higher than debug, which would prevent these debug logs from being displayed, but would keep the error logs:
# (or a similar condition to check you are not on the production server)
if ( !__PACKAGE__->config->{dev} ) {
__PACKAGE__->log->levels( 'warn', 'error', 'fatal' ) if ref __PACKAGE__->log;
}