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What can you do in the before hook? - Where is the documentation?
by Gabor Szabo 28 Mar '14

28 Mar '14

Hi, I was looking to set a catch-all route that will show "site is closed" and reached https://metacpan.org/pod/Dancer#hook specifically the hook before => sub { construct. It says what does the sub receive but it does not say what can one do with it. If the return value matters, etc. I am wondering if such documentation exists and if it would be a good idea to include it here or to link to it? Gabor

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Why does send_file() require a path relative to pubdir?
by Warren Young 24 Mar '14

24 Mar '14

Dancer::send_file() gives a "No such file" error if you pass it an absolute path or one that is not directly relative to $pubdir. I'm using send_file() to send dynamically generated PDF files to the client from behind pretty routes. That is, I want '/pdf/foo.pdf' to generate and send: /home/me/app/pdfbuild/foo-$user-$yymmdd-$hhmmss.pdf The generated PDF file has the user name in it so that other users don't clobber each others' generated PDFs. The file name contains a timestamp because the data that goes into the PDF changes frequently, so a second access of the URL needs to re-generate the PDF. Because of all this dynamic generation, I'm doing the background work in this pdfbuild directory, because I don't want to expose the intermediate files. I've fixed this by putting the intermediate files in pdfbuild and the final output PDF in .../pdfbuild/../public/pdf but this effectively exposes all generated PDFs: any user can pull up any other user's dynamic PDF if they know another user name and can make sensible guesses about the timestamp. Obviously I could add a nonce to the file name to make guessing impossible, but that's solving the symptom, rather than attacking the actual source of the problem. Why doesn't send_file() just return a binary blob to Dancer, which it recognizes and inserts literally into the response content body? Why does it care where on the filesystem that data comes from?

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Automatic JSON serializer breaks error page
by Warren Young 24 Mar '14

24 Mar '14

Apparently you cannot have both serializer: "JSON" show_errors: 1 in your config.yml. Enabling the automatic JSON serializer defeats the error screen, returning the exception error object as JSON to the client: { "exception" : "Text::Xslate: LoadError: Cannot find 'foo.tx' (path: /home/bla/qux) at /usr/lib/perl5/site_perl/5.8.8/Dancer/Template/Xslate.pm line 52.\n", "error" : "Text::Xslate: LoadError: Cannot find 'foo.tx' (path: /home/bla/qux) at /usr/lib/perl5/site_perl/5.8.8/Dancer/Template/Xslate.pm line 52.\n" } Is there a way I can fix this without going back to manual JSON encoding? (i.e. Setting content_type('application/json') and using to_json() on objects in route handlers.)

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after hook breaks send_file()
by Warren Young 24 Mar '14

24 Mar '14

Part of the web app I'm porting to Dancer builds dynamic PDF files for the client when they hit certain URLs. I'm generating these files in the route handler, then calling Dancer::send_file() at the end of the route handler. All of this is working fine, except that I was getting a 500 error on the send_file call: [8802] error @0.035479> [hit #16]request to GET /pdf/foo.pdf crashed: Too late to set another cookie, headers already built at /usr/lib/perl5/site_perl/5.8.8/Dancer/Response.pm line 166. in /usr/lib/perl5/site_perl/5.8.8/Dancer/Handler.pm l. 98 After some debugging, I found that all it takes to cause this is to add this to a freshly-generated lib/myapp.pm: hook after => sub { my $sid = session->id; }; That's it, merely *accessing* the session object after send_file() is called causes the error.[*] I was able to fix this by putting this at the top of the after hook: return if request->path =~ m{\.pdf$}; I'm not sure if this creates a backdoor to my app's dynamic PDFs or not, bypassing session management. My initial thought is that it doesn't, but data security can be tricky, and requires more thought than I've been able to give this so far. Bottom line, is there any good reason why my after hook should not be able to a) check the Dancer session object; and b) redirect the user to another page, even though we've already scheduled a file download? [*] My actual "after" hook code is more involved, checking whether our back-end server marked this session ID as invalid. If it is, I redirect the user to '/' to make them log back in again. I do this in the "after" hook because it isn't until after I try talking to the back-end server that I learn whether it still believes we're logged in. Putting this in the "after" hook satisfies the DRY principle, since a worse alternative is to wrap all back-end server calls with "are we still alive?" checks. Another poor alternative is to "ping" the back-end server in the "before" hook, but that's wasteful and creates a race condition.

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All starman workers have one (deleted) file open in lsof, seem hung on an flock call
by Mike South 18 Mar '14

18 Mar '14

Hi, I recently had a problem come up with my D1 app. I have the app writing the PID to the database at start and stop of a particular route, and I have two runs that never completed. I did an strace on the worker and it looked like this: [root@host ~]# strace -p 26508 Process 26508 attached - interrupt to quit flock(10, LOCK_EX lsof on that process gave me starman 26508 apps 10wW REG 8,22 0 24 /tmp/3j6mXZXwWM (deleted) (not sure, but I think the 10 in the flock call and the 10 in the 10wW mean that we're talking about the same file?). After a little more digging I found that every starman worker had that file open (except with 10w instead of 10wW for all but the one above and stracing a few of the other workers showed the same output ( "flock(10, LOCK_EX" ) as above. I started it up from a script with qx{ plackup --server Starman --port $port --workers 50 --env $env --pid=$run_file --daemonize bin/app.pl --error-log logs/$env.log } Anyone have any idea what that file would be, and whether this is indicative of any problem? Normally I expect to see a "listen(..." call when I do an strace, which I think means the worker is waiting for a connection. This looks to me like it's trying to get a lock on a file to write to it, but I don't know what that file would be, etc. Any help would be greatly appreciated. mike

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Serving big static and private files
by Gabor Szabo 13 Mar '14

13 Mar '14

Hi, you might know that the Perl Maven site http://perlmaven.com/ runs on Dancer. Up till yesterday it was running on Starman as the web server, but yesterday I added Nginx to the mix. So now it is Nginx - Starman(Dancer). One of the reasons I made the change is that there are a few large static files (some videos/screencasts and mp3 files) that I think would be better served by Nginx directly. I can configure that in Nginx (have not done it yet), but some of these files should be only available to paying users. As long as everything went through Dancer this was easy. in the route serving the file I checked if the request comes from an authenticated user and if she has the right subscription and only served the file if everything was fine. I am not sure how to do this when the files are served directly by nginx. Is there a solution? Any recommendations? regards Gabor

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Dancer Multi language
by Hugues 13 Mar '14

13 Mar '14

Hello I would like to use Dancer to create a new website with multi language support ( English, French, Russian, and Chinese/Korean ) I use already dancer for my job, ( Dancer 1 , Twitter bootstrap, Template TK ) I've seen this plugin Dancer::Plugin::I18N What is best way ( or best practice ) to do that? thanks Hugues.

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Dancer::Plugin::SimpleCRUD use of template
by Gert van Oss 10 Mar '14

10 Mar '14

Dear Dancers, Enjoying Dancer::Plugin::SimpleCRUD. Really a great tool. Just one thing I'm having a problem with is the use of a template. Is it possible to adjust the view that comes out of the box and where can I find this view? If not then reading the docs it says that: "a template must have a "simple_crud" placeholder defined or you won't get any output. This template must be located in your "views" directory." This maybe should all be obvious but setting up a view with [% render_content %] doesn't work. Should I define all database fields in the template? Thanks, Gert

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Changing paths for testing purpose
by Cymon 08 Mar '14

08 Mar '14

Hi, I wrote this test: use strict; use warnings; use Test::More; use Test::TCP; use LWP::UserAgent; use FindBin; use t::testapp::lib::Site; BEGIN { $ENV{DANCER_VIEWS} = "views"; } Test::TCP::test_tcp( client => sub { my $port = shift; my $ua = LWP::UserAgent->new; my $res = $ua->get("http://127.0.0.1:$port/admin"); ok($res->is_success); }, server => sub { my $port = shift; use Dancer2; set(show_errors => 1, startup_info => 0, port => $port, logger => 'capture', log => 'debug', ); Site->runner->server->port($port); start; }, ); done_testing; t::testapp::lib::Site is just a dummy app I created as environment to test libraries. Problem is that it search for views in t/testapp/views, but I want it to find them under t/../views. I know that running the test as DANCER_VIEWS=views t/001_app.t it works but how can i force DANCER_VIEWS=views inside the code? I tried $ENV{DANCER_VIEWS} = $other_path but it's not working... Thank you! -- Cymon http://perlishscrewdriver.blogspot.com

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Paypal
by Lyn St George 06 Mar '14

06 Mar '14

I recently put Dancer::Plugin::PaypalExpressRoutes on CPAN. This is an interface to Business::PayPal::API::ExpressCheckout, and registers three keywords for completing a transaction: ppsetrequest, ppgetrequest, ppdorequest. For convenience it also registers getppdetails, which gives access to the details hash of customer data returned from the ppgetrequest call, and getppresult which gives access to the results hash of transaction data returned from the final ppdorequest. The documentation contains further details and examples of routes in your site.pm I use it under the Interchange6 plugin, but I suppose it should work under any Dancer app with the appropriate configuration. Lyn

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