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

dancer2's prototype is there, feedback needed
by sukria 05 Oct '12

05 Oct '12

Hi there, I am very glad and proud to announce here that I've came up with a prototype of dancer2 that pleases me enough to be advertised. -*- https://github.com/sukria/dancer2 -*- dancer2 is a complete rewrite of Dancer aiming at providing the same awesomeness with the following major changes: - no more globals in the core - 100% object-oriented backend (based on Moo) - better scoping for sub-applications - better design (no more encapsulation violations, Law of Demeter, ...) The prototype I've pushed to GitHub currently covers ~80% of the DSL of Dancer. It's able to run simple applications (it can run the PerlDancer.org website for instance). Of course, with your real-life applications, it will break in many places in this current shape, and this is where you can help. I'd like to have as many reports as possible regarding upgrades tests. You can test very easily your app with dancer2: $ git clone http://github.com/sukria/dancer2.git $ cd YOUR_APP $ perl -I../dancer2/lib bin/app.pl Also, important to know: most of the plugins may not be working well. Thanks a lot ;)

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a REST question immediately followed by a Dancer-implementation question
by Mr. Puneet Kishor 30 Sep '11

30 Sep '11

So, I have a lot of methods such as get '/foo' => { .. }; get '/bar' => { .. }; get '/baz' => { .. }; get '/qux' => { .. }; All the above methods are reachable via a browser in which they depict some visual representation of the data. Most of the above methods have their '.:format' counterparts, mostly returning JSON packets when reached either via the browser or via the command line. All the methods above return something by default or modified by parameters. So, "http://server/app/foo" may work, or may require some parameters as in "http://server/app/foo?age=27&before=yesterday&for=rascals" I would like to implement a "meta" method, say get '/rest' => { .. }; which should return a listing of all the methods above, along with their parameters, if any, and whether those parameters are optional or required. http://server/app/rest {"resources": [ {"name": "foo, "params": [ {"required": [ {"name": "age", "type": "int"} ]}, {"optional": [ {"name": "before", "type": "string"} {"name": "for", "type": "string"} ]}, ]} ]} In other words, this meta method returns all the resources available at the http://server/app. Of course, I could code this for each app, but it would be nice to automate it. Suggestions? Ideas? -- Puneet Kishor

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Global app-wide "prefix" settings
by Assaf Gordon 28 Sep '11

28 Sep '11

Hello, (Somewhat related to the previous thread of "Deploying many many apps") Is there a way to specify a application-wide "prefix" settings ? The "prefix" keyword affects only the routes subroutines, but not the static/public files. For example, With WSGI/Pylon, they have a "prefix" settings that can be specified in the INI file, and that affects all the components of the application (including static files). This allows the following: 1. Write your application as usual (so route '/' is really '/', and images are /images/XXXX.jpg and javascripts are in /javascript/XXXX.js, etc.) 2. Add a "prefix" setting to the INI file (e.g. "prefix=dancer"), now: the root route because "/dancer/", images come from /dancer/images/XXXX.jpg javascripts come from /dancer/javascripts/XXXXX.js css files come from /dancer/css/XXXXXX.css etc. 3. In Apache (or NGinx), do something like: RewriteRule ^/dancer/images/(.*) /home/gordon/projects/my_dancer_app/public/images/$1 [L] RewriteRule ^/dancer/javascripts/(.*) /home/gordon/projects/my_dancer_app/public/javascripts/$1 [L] RewriteRule ^/dancer/css/(.*) /home/gordon/projects/my_dancer_app/public/css/$1 [L] RewriteRule ^/dancer(.*) http://localhost:3000$1 [P] The outcome: 1. Static content is served by Apache directly, doesn't even go to the application (based on a "rewrite_rule"). 2. Multiple applications can be deployed with different URL-prefix, without changing a single line of code in the application (just in the INI file). Does Dancer support something similar ? I haven't deployed a production server yet, but I'm planning do do so with several applications running on the same server (with different prefixes), and after reading Dancer::Deployment I'm still not sure what's the recommended way to do so. suggestions are very welcomed, -gordon

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How to set config-environments when using Dancer as script
by Assaf Gordon 28 Sep '11

28 Sep '11

Hello, I want to use "Dancer" (with some plugins, especially Database) from a command-line script, to accompany my website (some sort of behind-the-scenes access to the website infra-structure). But I've noticed that Dancer (when used with ":script" option) ignores any command line arguments, and so the "environment" can't be set, and so the configuration settings are always loaded from "development.yml". Example: === use Data::Dumper; use Dancer ':script'; use Dancer::Plugin::Database; ## too late - dancer already initialized with "development" environment setting ( "environment" => "production" ) ; my @result = database->quick_select( ### Whatever ### ) ; print Dumper(\@result),"\n"; === A work-around is to load Dancer with ":syntax" and initialize manually, but is this the best way? === use Data::Dumper; use Dancer ':syntax'; use Dancer::Plugin::Database; setting( "environment" => "production" ) ; Dancer::_init_script_dir($0); Dancer::Config->load; my @result = database->quick_select( ### Whatever ### ) ; print Dumper(\@result),"\n"; === Perhaps I'm doing something wrong, so any help is appreciated. Thanks, -gordon

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Memcached beginners problem
by Niels Larsen 27 Sep '11

27 Sep '11

Greetings, I, a Dancer newcomer, have trouble getting Dancer::Session::Memcached to work. All works with session Simple, but with memcached I get the error below. The memcached server was started with ./memcached (responds on port 11211) and the Cache::Memcached module is installed. The application was started with just ./application.pl --environment development, and the development.yml file has in it session: "memcached" memcached_servers: "127.0.0.1:11211" I did not 'use Dancer::Session::Memcached' because documentation does not say so, and I'm sure its a dumb mistake by me. But the crash is not so informative, and the format of the listing could be also be improved: module names (not file names) and line numbers should be at the left so they line up, and the traceback should include application code. It only shows Dancer code. And a wish: the Messagepack library is the fastest serialization method, I think, and I hope Dancer will support it some day. I use it already, and Kyoto Tycoon for permanent storage, works well. Unlike Membase/cache one can save pretty big strings, which reduces the number of times one must touch the storage, which again speeds the whole thing. Niels Larsen http://genomics.dk ------------------------------------------------------------------------ Error 500 runtime error Warning caught during route execution: Use of uninitialized value $key in concatenation (.) or string at /home/donate/DONATE/Software/Package_installs/Perl_modules/lib/perl5/Cache/Memcached.pm line 521. 518 $exptime = int($exptime || 0); 519 520 local $SIG{'PIPE'} = "IGNORE" unless $FLAG_NOSIGNAL; 521 my $line = "$cmdname $self->{namespace}$key $flags $exptime $len \r\n$val\r\n"; 522 523 my $res = _write_and_read($self, $sock, $line); 524 ------------------------------------------------------------------------

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Plugin::Database - suggestion to read username/password from a different file
by Assaf Gordon 26 Sep '11

26 Sep '11

Hello Dancers, Somewhat related to the "sensitive" config data in SCM" topic discussed recently, I would like to suggest the followng small patch to "Dancer::Plugin::Database" : Instead of specifying "username/password" in your yml config file, I've added a new setting called "credentials". This one points to a simple text file that would contain the user name and password. With this one can checkin all the configuration files, never worrying about passwords. Samba uses similar option in "smbclient" . So my new config looks like this: ==== plugins: Database: driver: 'mysql' database: 'devdb' credentials: 'database.secret' ===== And the username password are stored in "database.secret": ===== $ cat database.secret username=myuser password=mypassword ==== The patch is available here: https://github.com/agordon/Dancer-Plugin-Database/commit/5564d0c729899c45b8… Comments are welcomed, -gordon

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serving static and dynamic content separately
by Mr. Puneet Kishor 18 Sep '11

18 Sep '11

Pursuant to my earlier post in which I expressed curiosity about serving static and dynamic content from different servers, I have the following (not directly Dancer related but causing me to sub-optimally serve Dancer content) problem. I am unable to configure apache2 frontend proxy to Starman and also serve apache2 content. My intent is to have apache2 serve some static content and some dynamic apps, both with domain names and those as sub-folders of the document root, and also serve some dynamic apps, both with domain names and without, proxied behind apache2. In other words, I want to do the following http://my.server.edu/ (served by apache2 from "/Users/me/Sites") http://my.server.edu/lib (served by apache2 from "/Users/me/Sites/lib") http://my.server.edu/app0 (served by apache2 from "/Users/me/Sites/app0" http://my.server.edu/app1 (served by Starman from "Users/me/Docs/www/app1") http://vapp1.org (served by Starman from "Users/me/Docs/www/vapp1") http://vapp1.org/lib (served by apache2 from "/Users/me/Sites") http://subapp.vapp1.org (served by Starman from "Users/me/Docs/www/subapp") http://subapp.vapp1.org/lib (served by apache2 from "/Users/me/Sites") Here is my (simplified) conf file with my intent and the unexpected exhibited behavior in the comments. #################################################### # Default settings for http://my.server.edu/ #################################################### Listen 80 ServerName my.server.edu:80 DocumentRoot "/Users/me/Sites" <Directory /> Options FollowSymLinks AllowOverride None Order deny,allow Deny from all </Directory> <Directory "/Users/me/Sites"> Options FollowSymLinks AllowOverride None Order allow,deny Allow from all </Directory> #################################################### # Static content for http://my.server.edu/lib #################################################### Alias /lib "/Users/me/Sites/lib" # The server responds with a "502 Bad gateway" error ScriptAlias /cgi-bin/ "/Users/me/cgi-bin/" <Directory "/Users/me/cgi-bin"> AllowOverride None Options None Order allow,deny Allow from all </Directory> #################################################### # Proxies #################################################### ProxyRequests Off <Proxy *> Order deny,allow Allow from all </Proxy> # The following app should get their static content # from http://my.server.edu/lib, but the server responds # with a "502 Bad gateway" error #################################################### # http://my.server.edu/app1 #################################################### ProxyPass /app1 http://127.0.0.1:5000 ProxyPassReverse /app1 http://127.0.0.1:5000 # The server responds with a "502 Bad gateway" error # when serving static content #################################################### # Virtual host http://vapp1.org #################################################### <VirtualHost *:80> ServerName vapp1.org #################################################### # Static content for http://vapp1.org/lib #################################################### Alias /lib "/Users/me/Sites/lib" ProxyRequests Off <Proxy *> Order deny,allow Allow from all </Proxy> ProxyPass / http://127.0.0.1:5001 ProxyPassReverse / http://127.0.0.1:5001 </VirtualHost> ##################################################### # Virtual host subdomain http://subapp.vapp1.org ##################################################### <VirtualHost *:80> ServerName subapp.vapp1.org # The server responds with a "502 Bad gateway" error # when serving static content #################################################### # Static content for http://subapp.vapp1.org/lib #################################################### Alias /lib "/Users/me/Sites/lib" ProxyRequests Off <Proxy *> Order deny,allow Allow from all </Proxy> ProxyPass / http://127.0.0.1:5002 ProxyPassReverse / http://127.0.0.1:5002 </VirtualHost> As you can see from above, if I have the virtual host segments in my conf file, the server responds with a "502 Bad gateway" error for everything that is supposed to come from http://my.server.edu. However, if I remove the virtual host segments, all other apps work just fine. I am sure I had this working on a previous machine, but now I am unable to reproduce that. What am I doing wrong?

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OT: sysadmins guys mock Dancers
by Dave Doyle 16 Sep '11

16 Sep '11

Hi Dancers, Sorry for the OT. Just thought this was amusing. My team came back from lunch yesterday to find the center of our pod newly decorated: http://i.imgur.com/umSpt.jpg Our SysAdmins have noticed my teams recent fetish for Dancer (2 restful API's, a new client facing dancer app and a new internal dancer app coming soon). This is the result. (for those not all to familiar with what's hanging there, see: http://en.wikipedia.org/wiki/Dance_Dance_Revolution ) Keep on dancin', meraxes -- dave.s.doyle(a)gmail.com

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Input-validation and Error-Handling in a fun 'dancer' way
by Assaf Gordon 15 Sep '11

15 Sep '11

Hello Dancers, I have another dancer-newbie question: Is there a recommended way to verify input (or general variables) and report errors to the user ? Common scenario: I have a form with 3 inputs, and they need to by in a certain format (verifiable by a simple regex). If the inputs do not conform, I want to: 1. Log the error for later inspection 2. Inform the user (e.g. using Plugin::Dancer::FlashMessage) (The error message reported to the user is not necessarily the same one written to the log, if I wish to include more technical details in the log, or be more descriptive and verbose to the user). 3. Stop processing the request. And I wish to do it in the most 'fun' dancer kind of way. Looking at a naive implementation (below), there's alot of redundant code for validating and reporting the error back to the user (and more validation code than actual processing code). Any suggestions ? Thanks! -gordon ==================== post '/dosomething' => sub { my $email = params->{email}; my $gene = params->{gene}; my $cutoff = param->{cutoff}; if (!defined $email) { warning "Missing email address"; flash error => 'Missing email address'; return template 'form_errors' ; } elsif (!valid_email($email)) { warning "Got Invalid email address: $email"; flash error => 'Invalid email address"; return template 'form_errors' ; } if (!defined $gene) { warning "Missing gene identifier"; flash error => 'Missing gene identifier'; return template 'form_errors' ; } elsif (!valid_gene_identifier($gene)) { warning "Got Invalid gene identifier: $gene"; flash error => 'Invalid gene identifier"; return template 'form_errors' ; } if (!defined $cutoff) { warning "Missing cutoff identifier"; flash error => 'Missing cutoff identifier'; return template 'form_errors' ; } elsif (!valid_cutoff_value($cutoff)) { warning "Got Invalid cutoff value: $cutoff"; flash error => 'Invalid Cutoff value: must a value between 0.1 and 0.55'; return template 'form_errors' ; } ## Input IS OK, do some processing and return the result my ($result, $error) = process($email, $gene, $cutoff); template 'result.tt', { email => $email, cutoff => $cutoff, gene => $gene, result => $result, error => $error, }; }

5 5

Bug in Dancer::Request (+1-line patch)
by Richard Huxton 14 Sep '11

14 Sep '11

Current version of Dancer (1.3072) Line 52: sub forwarded_for_address { $_[0]->env->{X_FORWARDED_FOR} } Should read: sub forwarded_for_address { $_[0]->env->{HTTP_X_FORWARDED_FOR} } At least with my install of Apache on Debian. It's possible that the intention is to strip the HTTP_ from env entries, but it doesn't look like it here. I also suspect some of the other env vars might be missing a HTTP_ too. -- Richard Huxton Archonet Ltd

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