January 2016 - dancer-users - lists.preshweb.co.uk

D2 compatibility with Perl 5.8
by Warren Young 14 Jan '16

14 Jan '16

We recently rejected a plan to migrate to D2 when we discovered that Dancer2::Text::Xslate requires Perl 5.10. We still have to support 5.8 because we have an existing fleet of CentOS 5 boxes which aren’t going away any time soon. (Upgrading them in the field is as good as impossible, and we lack a good business reason to have them shipped back to be upgraded. They won’t go away until our customers just stop using them, or they fall over dead and need to be replaced.) Is dropping Perl 5.8 support an intentional move? If so, we’ll have to stick with D1 for years to come. I know the Modern Perl movement is trying to get beyond 5.8, but the fact is, it was the primary version of Perl for nearly 5 years, so it left a big “pulse” in the timeline that will take a long time to dissipate. Incidentally, a big factor in our choice to use Dancer 1 was that it still supports Perl 5.8. We rejected Catalyst and Mojolicious without even evaluating them because they both require Perl 5.10.

5 7

Using Dancer::Exception -- searching for best patterns
by Hermann Calabria 13 Jan '16

13 Jan '16

Following this useful Advent about Dancer::Exception: http://advent.perldancer.org/2011/6 I am attempting to refactor exception handling in a large D1 app, using Dancer::Exception. Ideally I’d like to Raise Friendly => ‘Some Friendly Error Message’ to report user-friendly error messages without logging, and everything else (whether raised by Dancer, die(), or by something else such as a database error) should just report “Internal Server Error” and log it. Furthermore, I’d like to be able to use Raise Friendly => ‘Some Friendly Error Message’ anywhere within the route code or within any package used by the route (example below uses Some::Package). See code below. It *appears* to work for all shown cases (1, 2, 3a-3d), but I would really appreciate critique and recommendations. In particular: 1. I don’t want to repeat the same catch {} section within every single route (following principles of D.R.Y.), so would really appreciate recommendations for cleanup. I tried using hook before_error_init and before_error_render but got nowhere fast (maybe I shouldn’t have given up?) 2. Am I using register_exception(‘Friendly’); correctly? I get a compilation error if I attempt to register_exception(‘Friendly’); within Some::Package. 3. Following D.R.Y., it would be nice to not have to register_exception(‘Friendly’) in every single route. I tried declaring it within app.pl but got the expected compilation error. Thanks all, Hermann --- package mytest; use strict; use Dancer ':syntax'; use Dancer::Exception qw(:all); register_exception('Friendly'); use lib "/home/s1/modules"; use Some::Package; get '/' => sub { try { # Case 1 Raise Friendly => ‘Friendly within mytest’; # Case 2 die ‘Unfriendly within my test’; # Case 3a-3d &Some::Package::Test(); } catch { my ($exception) = @_; if (ref($exception) =~ /^Dancer\:\:Exception/) { if ($exception->does('Friendly')) { status 400; return "got a friendly exception: " . $exception->message; } warning 'got an unknown exception to rethrow'; $exception->rethrow; } die $exception; }; }; ---- package Some::Package; use Dancer ':syntax'; use Dancer::Plugin::Database; use Dancer::Exception qw(:all); return –1; sub Test { # Case 3a: raise Friendly => 'A friendly error within Some::Package’; # Case 3b: die ‘Unfriendly within Some::Package’; # Case 3c: database error (unfriendly) database(‘mydb’)->selectrow_array("SELbarfECT 1"); # Case 3d: Some other package &Some::Other::Package::Test(); }; ----- And for completeness, app.pl: use strict; use Dancer; use mytest; dance;

2 2

Default config for DPAE::Provider::DBIC
by Andrew Beverley 13 Jan '16

13 Jan '16

Dear all, I'm in the process of improving the docs for Dancer2::Plugin::Auth::Extensible::Provider::DBIC, and have just realised that I chose some poor defaults for the configuration. I'd like to fix this, but I realise that it has the potential to break people's code. I'd like to get a feel for whether anyone actually uses the defaults though, to see whether this is likely to be a problem. I suspect that nobody will be using the defaults, hence the desire to change them. The 3 settings are "users_table", "roles_table" and "user_roles_table". The defaults are currently "users", "roles" and "user_roles", but I would like to change them to "user", "role" and "user_role" respectively. This would bring them into line with standard DBIC naming practices (they are actually lower case versions of the resultset). The names of these keys are misleading, but that is another topic of conversation. Any thoughts welcome, Andy

1 2

Logging and handling errors made easy
by Andrew Beverley 13 Jan '16

13 Jan '16

A few of you may have seen my talk about Dancer2::Plugin::LogReport and Dancer2::Logger::LogReport. The modules aim to make logging and handling errors (both user and application) nice and easy. For those that haven't, or those that have and would like a recap, I have written a Dancer advent article: https://github.com/abeverley/advent-calendar/blob/master/2015/9-easy-except… I'll post an updated link as and when required. I realise that the modules can be quite complicated, so I'm very happy to answer questions, either here or on IRC. Andy

1 0

Non-blocking stuff
by David H 12 Jan '16

12 Jan '16

Hi All, I'm looking for some advice/pointers on having stuff non-block in my code. I have an application which runs on Dancer2 and is ~12,000 lines of code. It is actually (currently) four separate applications. It works really really well at the moment but for one thing, and that is that it continually blocks on pretty much everything. I've tried various solutions including starman which doesn't seem to run its allocated 10 workers for some reason. I've seen the model of nodejs and I'm looking for something similar to the call-back event non-blocking model of nodejs. I've tried using the apache road but that seems to recompile on every request, which adds ~ 1.5 seconds to each request, since that is the application startup time. Keen to see how other people solve this. Thanks, David

4 13

Perl::Dancer Conference 2016 - Meeting 2016-01-11
by Sam Batschelet 12 Jan '16

12 Jan '16

Fellow Dancer, Happy New Year! It is my pleasure to announce that the next iteration of the Perl::Dancer Conference will take place in 2016. In the spirit of open source we are going to host a meeting on IRC Monday January 11th on the #dancer channel (irc.perl.org) at 3pm CET (9am EST). The meeting will take input on date / venue and general improvements. See you then! Sam Batschelet Perl::Dancer conference 2016. https://www.perl.dance

1 1

Code behaves differently on digitalocean.
by Richard Reina 10 Jan '16

10 Jan '16

This code works (the file uploads) when I run it from my web app on my local host. However, it does not when I try it on the digitalocean version of my app. I get no errors and $file->copy_to($destination) returns true. But the file does not upload. Anyone have an idea as to what the problem could be? post '/upload' => sub { my $user_id = session 'UID'; my $d_filename = 'user_' . $user_id . '.jpg'; my $file = request->upload('file'); my $tmpname = $file->tempname; my $destination = $upload_dir . '/' . $d_filename; my ($crslt) = $file->copy_to($destination) || warn $!; unlink $tmpname if -e $tmpname; debug "crslt: ", $crslt; template 'upload'; redirect '/playerdash'; };

4 5