February 2011 - dancer-users - lists.preshweb.co.uk

Dancer::Plugin best practices.
by Carlos Ivan Sosa 18 Feb '11

18 Feb '11

I don't know if these is really a query about Dancer::Plugin or simple Perl module usage in which I'm a bit confused. But ever since I started my mini-blog engine with several of Dancer::Plugin's, it has grown to long to follow, so I decided to separate it by routes just like the cookbook suggested. http://search.cpan.org/dist/Dancer/lib/Dancer/Cookbook.pod#Using_the_prefix… My problem comes when I want to separate functions, and interexchange them between each different prefix route file in which my routes are divided. For instance, in my feed routes file I call a function that creates a database handler from Dancer::Plugin::Database, and from most of my routes files I use this database handler. But each section does a different SQL query to a different table depending on the entry. So I came up with a package that calls Dancer::Plugin:Database, and works around with the two tables logic. package log::db; use strict; use Dancer::Plugin; use Dancer::Plugin::Database; register _connect_db => sub { my $db = database(); return $db; }; register _sql => sub { my ($table, $url) = @_; my $db = _connect_db(); my $sth = $db->quick_select($table, { url => $url}) or die $db->errstr; return $sth; }; register_plugin; 1; ... This is the feed route file: package log::feed; use Dancer ':syntax'; use log::db; use Dancer::Plugin::Feed; use DateTime::Format::Strptime; sub _feed_sql { my $db = _connect_db(); my $sql = 'select id, title, url, text, datetime from entries order by id desc'; my $sth = $db->prepare($sql) or die $db->errstr; $sth->execute or die $sth->errstr; my $entries = $sth->fetchall_arrayref({}); return $entries; } ... So I don't know if I'm doing the best practice habit, because that is my work around. So I'm asking what would be the best way or the "Perl way" for a kwalitee package. I find these more clean and helpful than doing a full-on Perl module, which never seem to work for me. Modules are still too abstract for me. My apologies for a huge mail. Cheers.

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Template engines
by Oleg A. Mamontov 16 Feb '11

16 Feb '11

Hello! There is very interesting template system at CPAN - Text::Xslate (http://search.cpan.org/~gfuji/Text-Xslate/) The module is relative young but nice and power. Author post his benchmark of other popular template system: (http://search.cpan.org/~gfuji/Text-Xslate/lib/Text/Xslate.pm#High_performan…) Briefly: Text::Xslate is faster than TT over 100 times. It's impressive. There are other interesting possibilities: smart html escaping and template cascading (often called `template inheritance`). For those who first heard about it i illustrate: assume a base template with 3 blocks: 'left','center' and 'right'. Now you can inherit your page from this template and override one, two or all of this blocks together. This method compares favorably with traditional 'wrapping' method (where you generate `content` and wrap it with `layout`). Template inheritance present in many template system in Python world: Cheetah, Django, Mako and others. Now it is in Perl! That's all lyrics, now the bad news :) There is Dancer wrapper at CPAN: http://search.cpan.org/~franckc/Dancer-Template-Xslate/ But after several unsuccessful attempts to use it i realized one simple thing: Dancer idea of template engine is not compatible with Text::Xslate fundamentally. Dancer try to resolve absolute template file name, render with template system and wrap result with `layout`. I understand that this way Dancer provides same functionality between different template engines. It also allow `auto_page` feature. It is valuable but we lose amazing features and working speed of Text::Xslate :( This template system is designed for self-searching template file in list of search directories. Unfortunately I have no good ideas on how to combine Dancer with Text::Xslate but I feel that this should be done :) I am familiar with the dancer recently and may not take into account any nuances. Any ideas and advice are welcome! Thank you. -- Cheers, Oleg A. Mamontov mailto: oleg(a)mamontov.net jabber: lonerr(a)charla.mamontov.net icq uin: 79-521-617 cell: +7-903-798-1352

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Conditional HTTP proposal
by Oleg A. Mamontov 15 Feb '11

15 Feb '11

Hello. I create small patch to enhance static files serving functionality. During development process its important to refresh pages quickly. Conditional HTTP requests is the good choise. Seems like working, but needs more testing :) --- Dancer/Renderer.pm.orig 2011-02-10 19:31:07.000000000 +0300 +++ Dancer/Renderer.pm 2011-02-10 20:28:46.000000000 +0300 @@ -3,7 +3,9 @@ use strict; use warnings; use Carp; +use File::stat; use HTTP::Headers; +use POSIX qw( strftime ); use Dancer::Route; use Dancer::HTTP; use Dancer::Cookie; @@ -164,10 +166,16 @@ my $fh = open_file('<', $static_file); binmode $fh; - Dancer::Response->status($status); + # http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html + # Wed, 15 Nov 1995 04:58:08 GMT + my $lmod = strftime '%a, %d %b %Y %H:%M:%S GMT', gmtime(stat($fh)->mtime); + my $imod = Dancer::SharedData->request->header('If-Modified-Since') || ''; + + Dancer::Response->status( $lmod eq $imod ? 304 : $status ); Dancer::Response->content_type( get_mime_type($static_file)); - Dancer::Response::set_current_content($fh); + Dancer::Response::set_current_content($fh) unless $lmod eq $imod; + Dancer::Response->header('Last-Modified' => $lmod ); return Dancer::Response->current; } return; -- Cheers, Oleg A. Mamontov mailto: oleg(a)mamontov.net jabber: lonerr(a)charla.mamontov.net icq uin: 79-521-617 cell: +7-903-798-1352

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Problem with an open filehandler within the route
by Thomas Maier 15 Feb '11

15 Feb '11

Hi, I have the follow route: {{{ get qr{/(tests/.*)} => sub { my ($filename) = splat; my $testdata = {}; open my $stdout, "-|", "cli","--flag",$filename; while(<$stdout>) { my ($id,$name) = split/:/,$_; $testdata->{$id} = qq{$name}; } template 'show_test_case', { filename => $filename, testdata => $testdata, }; }; }}} Following the route (/tests/something) for the first time gives the expected results, meaning the list of $id's and $name's. But when executing the route for the second time, it shows the follow runtime error: " Warning caught during route execution: readline() on closed filehandle $stdout " Is there some limitation for working with filehandlers withing the route subroutine? Thomas

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reusing config.yml with environments
by Dave Doyle 14 Feb '11

14 Feb '11

Hiya, This may be a colossally stupid question. I have a webapp that has many nifty things in config.yml and different settings based on the envirnoment. I'd like to use the Dancer config for cli utilities (a data loader for example) and not have to manually munge together the config.yml and the envinroment/<whatever>.yml. I don't want to use YAML, load the config.yml, find the environment, find the environment config file, load it and merge it with the main config... because Dancer already does that. Now, something like this works for a script I've got in a "scripts" folder off the root of my Dancer app: #!/usr/bin/perl use common::sense; use FindBin; use Data::Dumper::Concise; use Dancer ':syntax'; use Dancer::Config; set appdir => "$FindBin::Bin/../"; set environment => 'production'; Dancer::Config->load(); say Dumper(config); This does it just fine. Granted, it's relatively small but it seems klugy to me. Anyone else done something like this? How do you do it? Is there a better way? Am I utterly blind? Thanks, D aka meraxes -- dave.s.doyle(a)gmail.com

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Plack Middleware for subdomains
by Matthew Vickers 14 Feb '11

14 Feb '11

Hi all, I have a need for the use of subdomains being mapped to accounts and could not find a plugin or middleware already written, so I have whipped up a Dancer::Middleware::Subdomain library and have it up on github. https://github.com/mvickers/dancer_middleware_subdomain Comments/Criticisms are welcome. Matt

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uri_path under CSS
by ambs 12 Feb '11

12 Feb '11

Hello, Is there any clean way to use uri_path under the CSS file? Probably create a template for the css file but that is too much trouble... ideas are welcome :) Cheers ambs

1 2

mime types
by Oleg A. Mamontov 11 Feb '11

11 Feb '11

Hello. I discovered some problems with Dancer::MIME under Starman::Server (type Net::Server::PreFork). After some debugging i found that MIME::Types (used in Dancer::MIME) read and parse mime types from it DATA handle. This handle is opening by Perl during module load procedure. But subsequent reads occured in &MIME::Types::init (which called from constructor). In Dancer flow it occurs after fork, in different processes concurrently. Thereby some processes had invalid MIME data. I propose three different solutions: 1. Remove MIME::Types from Dancer::MIME completely :) 2. Explicitly call &MIME::Types::init early (before fork): package Dancer::MIME; use strict; use warnings; use base 'Dancer::Object::Singleton'; use MIME::Types; MIME::Types->init; 3. Use MIME::Types later (in &Dancer::MIME::init): sub init { my ($class, $instance) = @_; eval "use MIME::Types"; $instance->mime_type(MIME::Types->new(only_complete => 1)); $instance->aliases({}); } What's more properly? Thank you. -- Cheers, Oleg A. Mamontov mailto: oleg(a)mamontov.net jabber: lonerr(a)charla.mamontov.net icq uin: 79-521-617 cell: +7-903-798-1352

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perldancer.org down ?
by Matthew Vickers 11 Feb '11

11 Feb '11

Hey all, I noticed that http://www.perldancer.org/ is down, something about an internal server error ? Cheers Matt

2 1

(resending) hello! (and cookie weirdness)
by Alex Knowles 09 Feb '11

09 Feb '11

Apologies if this arrives twice - I realised I hadn't confirmed my subscription when I first sent it... Hi all, Just signed up, we're just starting to use Dancer - so far it's all being awesome. However :) I hit a bit of a weird thing today - it's probably me misreading something. If I do this: set_cookie 'blah'=> "blah", expires => (time + 3600); as per the docs here: http://search.cpan.org/~sukria/Dancer-1.3003/lib/Dancer.pm#set_cookie the next time you visit it does a comparison in Dancer::Cookies::has_changed to see if it's been updated. The value it's checking against in this case is: ['blah'], which is then compared to "blah" and obviously aren't equal it then drops a replacement with 'blah', but missing the expiry - causing the cookie to expire immediately. either of these patches will work: +++ Cookies.pm 2011-02-09 17:30:11.000000000 +0000 @@ -40,6 +40,7 @@ sub has_changed { my ($self, $cookie) = @_; my ($name, $value) = ($cookie->{name}, $cookie->{value}); + $value=$value->[0] if ref $value eq "ARRAY"; or +++ Cookies.pm 2011-02-09 17:31:14.000000000 +0000 @@ -39,7 +39,7 @@ # return true if the given cookie is not the same as the one sent by the client sub has_changed { my ($self, $cookie) = @_; - my ($name, $value) = ($cookie->{name}, $cookie->{value}); + my ($name, $value) = ($cookie->{name}, $cookie->value); or maybe it's something in Dancer::Renderer, or Dancer::Cookie... Am I on the right track? or have I done something wrong in my cookie setting? cheers. Alex

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