Introduction to Dancer!A Sinatra-inspired web framework for Perl!!!Mark Allen!mrallen1@yahoo.com!http://byte-me.org!http://github.com/mrallen1!http://bitbucket.org/mrallen1!https://metacpan.org/author/MALLEN!

The Old Days!

The Old Days

cgi-lib.pl (1994-1998)!!

The Old Days

CGI.pm (1995-2011)!!

The Old Days

mod_perl (1996-2011)!!

The Old Days

Matt’s Script Archive (1995-2011)!

!Use instead:!

http://nms-cgi.sourceforge.net/!(Thanks London.pm)!

!

The Old Days

use CGI.pm;!!my $q = CGI->new();!my ($a, $b, $c) = $q->param();!!if ($a !~ /\d+/) {!!print $q->header(-status => ‘400 Bad request’);!!print “<h1>Value of ‘a’ ($a) is not an integer</h1>”;!!exit 0;!

}!# yada, yada!

The Old Days

.htaccess Hack!!!RewriteEngine On!RewriteBase /abc!!RewriteRule ^(.*)/(.*)/(.*)$ !abc.pl?a=$1;b=$2;c=$3!!

The Old Days

.htaccess Hack!!# Use Web 2.0 style URLs, but keep CGI interface!RewriteEngine On!RewriteBase /abc!!RewriteRule ^(.*)/(.*)/(.*)$ !abc.pl?a=$1;b=$2;c=$3!!

The Old Days

.htaccess Hack!!# Use Web 2.0 style URLs, but keep CGI interface!RewriteEngine On!RewriteBase /abc!!RewriteRule ^(.*)/(.*)/(.*)$ !abc.pl?a=$1;b=$2;c=$3!!

The Old Days

.htaccess Hack!!# Use Web 2.0 style URLs, but keep CGI interface!RewriteEngine On!RewriteBase /abc!!RewriteRule ^(.*)/(.*)/(.*)$ !abc.pl?a=$1;b=$2;c=$3!!

The Old Days

h"p://flic.kr/p/5TWTR4  

The Old Days

h"p://flic.kr/p/5TWTR4  

Move over bacon, now there’s something leaner.!

!

Move over bacon

Perl 5 Renaissance:!•  Moose!•  DBIx::Class!•  Plack!•  Tons of great new stuff in

core perl 5.10+!!!

Move over bacon

Do you find Catalyst too !heavyweight or intimidating?!

!

Move over bacon

!Me too!!

!!

Move over bacon

Enter Dancer!!

Move over bacon

Other Sinatra-inspired frameworks:!•  Mojo (Perl – TMTOWTDI)!•  Flask (Python)!•  Fitzgerald (PHP)!•  Express (Node.js)!!

Move over bacon

Dancer is:!•  Easy to learn!•  Expressive!•  Efficient!

Dancer is ...!!

Easy to learn!

Easy to learn

Basic Dancer concepts:!•  One (or more) HTTP verb(s)!•  A route!•  A handler!

Easy to learn

use Dancer;!!get '/' => sub {! return 'Hello World!\n’;!};!!start;!

Easy to learn

use Dancer;!!get '/' => sub {! return 'Hello World!\n’;!};!!start;!

Easy to learn

use Dancer;!!get '/' => sub {! return 'Hello World!\n’;!};!!start;!

Easy to learn

use Dancer;!!get '/' => sub {! return 'Hello World!\n’;!};!!start;!

Easy to learn

use Dancer;!!get '/' => sub {! return 'Hello World!\n’;!};!!start;!

Easy to learn

Easy to learn

get '/' => sub {! my $db = connect_db();! my $sql = 'select id, title, text from entries order by id desc’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute or die $sth->errstr;! template 'show_entries.tt', {! 'msg' => get_flash(),! 'add_entry_url' => uri_for('/add'),! 'entries' => $sth->fetchall_hashref('id'),! };!};!

Easy to learn

get '/' => sub {! my $db = connect_db();! my $sql = 'select id, title, text from entries order by id desc’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute or die $sth->errstr;! template 'show_entries.tt', {! 'msg' => get_flash(),! 'add_entry_url' => uri_for('/add'),! 'entries' => $sth->fetchall_hashref('id'),! };!};!

Easy to learn

get '/' => sub {! my $db = connect_db();! my $sql = 'select id, title, text from entries order by id desc’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute or die $sth->errstr;! template 'show_entries.tt', {! 'msg' => get_flash(),! 'add_entry_url' => uri_for('/add'),! 'entries' => $sth->fetchall_hashref('id'),! };!};!

Easy to learn

get '/' => sub {! my $db = connect_db();! my $sql = 'select id, title, text from entries order by id desc’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute or die $sth->errstr;! template 'show_entries.tt', {! 'msg' => get_flash(),! 'add_entry_url' => uri_for('/add'),! 'entries' => $sth->fetchall_hashref('id'),! };!};!

Easy to learn

get '/' => sub {! my $db = connect_db();! my $sql = 'select id, title, text from entries order by id desc’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute or die $sth->errstr;! template 'show_entries.tt', {! 'msg' => get_flash(),! 'add_entry_url' => uri_for('/add'),! 'entries' => $sth->fetchall_hashref('id'),! };!};!

Easy to learn

get '/' => sub {! my $db = connect_db();! my $sql = 'select id, title, text from entries order by id desc’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute or die $sth->errstr;! template 'show_entries.tt', {! 'msg' => get_flash(),! 'add_entry_url' => uri_for('/add'),! 'entries' => $sth->fetchall_hashref('id'),! };!};!

Easy to learn

get '/' => sub {! my $db = connect_db();! my $sql = 'select id, title, text from entries order by id desc’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute or die $sth->errstr;! template 'show_entries.tt', {! 'msg' => get_flash(),! 'add_entry_url' => uri_for('/add'),! 'entries' => $sth->fetchall_hashref('id'),! };!};!

Easy to learn

get '/' => sub {! my $db = connect_db();! my $sql = 'select id, title, text from entries order by id desc’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute or die $sth->errstr;! template 'show_entries.tt', {! 'msg' => get_flash(),! 'add_entry_url' => uri_for('/add'),! 'entries' => $sth->fetchall_hashref('id'),! };!};!

Easy to learn

get '/' => sub {! my $db = connect_db();! my $sql = 'select id, title, text from entries order by id desc’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute or die $sth->errstr;! template 'show_entries.tt', {! 'msg' => get_flash(),! 'add_entry_url' => uri_for('/add'),! 'entries' => $sth->fetchall_hashref('id'),! };!};!

Easy to learn

show_entries.tt!!<ul class=entries>! <% IF entries.size %>! <% FOREACH id IN entries.keys.nsort %>! <li><h2><% entries.$id.title %></h2>! <% entries.$id.text %>! <% END %>! <% ELSE %>! <li><em>Unbelievable. No entries here so far</em>! <% END %>!</ul>!!

Easy to learn

show_entries.tt!!<ul class=entries>! <% IF entries.size %>! <% FOREACH id IN entries.keys.nsort %>! <li><h2><% entries.$id.title %></h2>! <% entries.$id.text %>! <% END %>! <% ELSE %>! <li><em>Unbelievable. No entries here so far</em>! <% END %>!</ul>!!

Easy to learn

show_entries.tt!!<ul class=entries>! <% IF entries.size %>! <% FOREACH id IN entries.keys.nsort %>! <li><h2><% entries.$id.title %></h2>! <% entries.$id.text %>! <% END %>! <% ELSE %>! <li><em>Unbelievable. No entries here so far</em>! <% END %>!</ul>!!

Easy to learn

show_entries.tt!!<ul class=entries>! <% IF entries.size %>! <% FOREACH id IN entries.keys.nsort %>! <li><h2><% entries.$id.title %></h2>! <% entries.$id.text %>! <% END %>! <% ELSE %>! <li><em>Unbelievable. No entries here so far</em>! <% END %>!</ul>!!

Easy to learn

get '/' => sub {! my $db = connect_db();! my $sql = 'select id, title, text from entries order by id desc’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute or die $sth->errstr;! template 'show_entries.tt', {! 'msg' => get_flash(),! 'add_entry_url' => uri_for('/add'),! 'entries' => $sth->fetchall_hashref('id'),! };!};!

Easy to learn

show_entries.tt!!<ul class=entries>! <% IF entries.size %>! <% FOREACH id IN entries.keys.nsort %>! <li><h2><% entries.$id.title %></h2>! <% entries.$id.text %>! <% END %>! <% ELSE %>! <li><em>Unbelievable. No entries here so far</em>! <% END %>!</ul>!!

Easy to learn

show_entries.tt!!<ul class=entries> <!– CSS class -->! <% IF entries.size %>! <% FOREACH id IN entries.keys.nsort %>! <li><h2><% entries.$id.title %></h2>! <% entries.$id.text %>! <% END %>! <% ELSE %>! <li><em>Unbelievable. No entries here so far</em>! <% END %>!</ul>!!

Easy to learn

Directory structure !

dancr/!├── dancr.pl!├── public!│   └── css!│   └── style.css!└── views! ├── layouts! │   └── main.tt! ├── login.tt! └── show_entries.tt!

Easy to learn

Directory structure !

dancr/!├── dancr.pl!├── public!│   └── css!│   └── style.css!└── views! ├── layouts! │   └── main.tt! ├── login.tt! └── show_entries.tt!

Easy to learn

Directory structure !

dancr/!├── dancr.pl!├── public!│   └── css!│   └── style.css!└── views! ├── layouts! │   └── main.tt! ├── login.tt! └── show_entries.tt!

Easy to learn

Directory structure !

dancr/!├── dancr.pl!├── public!│   └── css!│   └── style.css!└── views! ├── layouts! │   └── main.tt! ├── login.tt! └── show_entries.tt!

Dancer is...!!

Expressive!

Expressive

post '/add' => sub {! if ( not session('logged_in') ) {! return send_error("Not logged in", 401);! }!! my $db = connect_db();! my $sql = 'insert into entries (title, text) values (?, ?)’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute(params->{'title'}, params->{'text'}) or die $sth->errstr;!! set_flash('New entry posted!');! redirect '/’;!};!

Expressive

post '/add' => sub {! if ( not session('logged_in') ) {! return send_error("Not logged in", 401);! }!! my $db = connect_db();! my $sql = 'insert into entries (title, text) values (?, ?)’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute(params->{'title'}, params->{'text'}) or die $sth->errstr;!! set_flash('New entry posted!');! redirect '/’;!};!

Expressive

post '/add' => sub {! if ( not session('logged_in') ) {! return send_error("Not logged in", 401);! }!! my $db = connect_db();! my $sql = 'insert into entries (title, text) values (?, ?)’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute(params->{'title'}, params->{'text'}) or die $sth->errstr;!! set_flash('New entry posted!');! redirect '/’;!};!

Expressive

post '/add' => sub {! if ( not session('logged_in') ) {! return send_error("Not logged in", 401);! }!! my $db = connect_db();! my $sql = 'insert into entries (title, text) values (?, ?)’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute(params->{'title'}, params->{'text'}) or die $sth->errstr;!! set_flash('New entry posted!');! redirect '/’;!};!

Expressive

post '/add' => sub {! if ( not session('logged_in') ) {! return send_error("Not logged in", 401);! }!! my $db = connect_db();! my $sql = 'insert into entries (title, text) values (?, ?)’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute(params->{'title'}, params->{'text'}) or die $sth->errstr;!! set_flash('New entry posted!');! redirect '/’;!};!

Expressive

post '/add' => sub {! if ( not session('logged_in') ) {! return send_error("Not logged in", 401);! }!! my $db = connect_db();! my $sql = 'insert into entries (title, text) values (?, ?)’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute(params->{'title'}, params->{'text'}) or die $sth->errstr;!! set_flash('New entry posted!');! redirect '/’;!};!

Expressive

post '/add' => sub {! if ( not session('logged_in') ) {! return send_error("Not logged in", 401);! }!! my $db = connect_db();! my $sql = 'insert into entries (title, text) values (?, ?)’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute(params->{'title'}, params->{'text'}) or die $sth->errstr;!! set_flash('New entry posted!');! redirect '/’;!};!

Expressive

Little Bobby Tables!

h"p://xkcd.com/327/  

Expressive

post '/add' => sub {! if ( not session('logged_in') ) {! return send_error("Not logged in", 401);! }! # http://bobby-tables.com! my $db = connect_db();! my $sql = 'insert into entries (title, text) values (?, ?)’;! my $sth = $db->prepare($sql) or die $db->errstr;! $sth->execute(params->{'title'}, params->{'text'}) or die $sth->errstr;!! set_flash('New entry posted!');! redirect '/’;!};!

Expressive

Expressive

Configuration !•  Session Engine!•  Template Engine!•  Logging !•  Plugins!

Expressive

Configuration Examples!set 'session' => 'Simple'; set 'template' =>'template_toolkit'; set 'logger' => 'console'; set 'log' => 'debug'; set 'show_errors' => 1; !

Expressive

Configuration Examples!set 'session' => 'Simple'; set 'template' =>'template_toolkit'; set 'logger' => 'console'; set 'log' => 'debug'; set 'show_errors' => 1; !

Expressive

Configuration Use any non-reserved key/value pair.set 'username' => 'admin'; set 'password' => 'password';!!

Expressive

Routes with regex!!get qr{\A\/(?<code>[A-Za-z0-9]+)\Z} => sub {! my $decode = decode_base36( uc captures->{'code'}! );! ...;!};!

Expressive

Routes with regex!!get qr{\A\/(?<code>[A-Za-z0-9]+)\Z} => sub {! my $decode = decode_base36( uc captures->{'code'}! );! ...;!};!

Expressive

Routes with regex!!use v5.10; get qr{\A\/(?<code>[A-Za-z0-9]+)\Z} => sub {! my $decode = decode_base36( uc captures->{'code'}! );! ...;!};!

Expressive

Routes with regex!!use v5.10; get qr{\A\/(?<code>[A-Za-z0-9]+)\Z} => sub {! my $decode = decode_base36( uc captures->{'code'}! );! ...;!};!

Expressive

Routes with named params!!get '/:code/stats' => sub {! my $decode = decode_base36( uc params->{'code'} );! ...;!};!

Expressive

Routes with named params!!get '/:code/stats' => sub {! my $decode = decode_base36( uc params->{'code'} );! ...;!};!

Expressive

Routes with named params!!get qr{^/(.+)/stats$} => sub { params(‘code’) = $1; # input sanity goes here ...; };!

Expressive

use CGI.pm;!!my $q = CGI->new();!my ($a, $b, $c) = $q->param();!!if ($a !~ /\d+/) {!!print $q->header(-status => ‘400 Bad request’);!!print “<h1>Value of ‘a’ ($a) is not an integer</h1>”;!!exit 0;!

}!# yada, yada!

Expressive

!!!!use v5.10; use Dancer; !get qr{/(?<a>\d+)/(?<b>.+)/(?<c>.+)} => sub {! # Route will only match if a is an integer! # No more sanitation/validation necessary ...; };!!

Dancer is...!

Efficient!

Efficient

any ['get', 'post'] => '/login' => sub {! my $err;! if ( request->is_post ) {! if ( params->{'username'} ne setting('username') ) {! $err = "Invalid username”;! }! elsif ( params->{'password'} ne setting('password') ) {! $err = "Invalid password”;! }! else {! session 'logged_in' => true;! set_flash('You are logged in.');! redirect '/’;! }! }! template 'login.tt', {! 'err' => $err,! };!};!

Efficient

any ['get', 'post'] => '/login' => sub {! my $err;! if ( request->is_post ) {! if ( params->{'username'} ne setting('username') ) {! $err = "Invalid username”;! }! elsif ( params->{'password'} ne setting('password') ) {! $err = "Invalid password”;! }! else {! session 'logged_in' => true;! set_flash('You are logged in.');! redirect '/’;! }! }! template 'login.tt', {! 'err' => $err,! };!};!

Efficient

any ['get', 'post'] => '/login' => sub {! my $err;! if ( request->is_post ) {! if ( params->{'username'} ne setting('username') ) {! $err = "Invalid username”;! }! elsif ( params->{'password'} ne setting('password') ) {! $err = "Invalid password”;! }! else {! session 'logged_in' => true;! set_flash('You are logged in.');! redirect '/’;! }! }! template 'login.tt', {! 'err' => $err,! };!};!

Efficient

any ['get', 'post'] => '/login' => sub {! my $err;! if ( request->is_post ) {! if ( params->{'username'} ne setting('username') ) {! $err = "Invalid username”;! }! elsif ( params->{'password'} ne setting('password') ) {! $err = "Invalid password”;! }! else {! session 'logged_in' => true;! set_flash('You are logged in.');! redirect '/’;! }! }! template 'login.tt', {! 'err' => $err,! };!};!

Efficient

any ['get', 'post'] => '/login' => sub {! my $err;! if ( request->is_post ) {! if ( params->{'username'} ne setting('username') ) {! $err = "Invalid username”;! }! elsif ( params->{'password'} ne setting('password') ) {! $err = "Invalid password”;! }! else {! session 'logged_in' => true;! set_flash('You are logged in.');! redirect '/’;! }! }! template 'login.tt', {! 'err' => $err,! };!};!

Efficient

any ['get', 'post'] => '/login' => sub {! my $err;! if ( request->is_post ) {! if ( params->{'username'} ne setting('username') ) {! $err = "Invalid username”;! }! elsif ( params->{'password'} ne setting('password') ) {! $err = "Invalid password”;! }! else {! session 'logged_in' => true;! set_flash('You are logged in.');! redirect '/’;! }! }! template 'login.tt', {! 'err' => $err,! };!};!

Efficient

any ['get', 'post'] => '/login' => sub {! my $err;! if ( request->is_post ) {! if ( params->{'username'} ne setting('username') ) {! $err = "Invalid username”;! }! elsif ( params->{'password'} ne setting('password') ) {! $err = "Invalid password”;! }! else {! session 'logged_in' => true;! set_flash('You are logged in.');! redirect '/’;! }! }! template 'login.tt', {! 'err' => $err,! };!};!

Efficient

any ['get', 'post'] => '/login' => sub {! my $err;! if ( request->is_post ) {! if ( params->{'username'} ne setting('username') ) {! $err = "Invalid username”;! }! elsif ( params->{'password'} ne setting('password') ) {! $err = "Invalid password”;! }! else {! session 'logged_in' => true;! set_flash('You are logged in.');! redirect '/’;! }! }! template 'login.tt', {! 'err' => $err,! };!};!

Efficient

Hook Before / After!•  De/Serialization!•  Rendering!•  Template!•  Errors!

Efficient

Forward!!get '/demo/foo/:bar' => sub {! my $bar = param->{'bar'};! # magically use demo DB! ...;! return forward "/foo/$bar";!};! !

Efficient

Prefix!!prefix '/user'; # begins scope!!get '/view/:id' => sub { ...; };!post '/add' => sub { ...; };!any ['get', 'post'] => '/edit/:id' => sub { ...; };!!prefix undef; # ends scope!!get '/view/:id' => sub { ...; };!

Efficient

Dancer Plugins add keywords!•  Auto-create RSS feeds!•  Integrate Twitter for authN!•  DBIx::Class!•  DWIM CRUD apps!•  ...and more!

Dancer is...!!

Awesome!!

Awesome

Source code:!hg clone https://bitbucket.org/mrallen1/dancr!!

See also:!https://metacpan.org/module/Dancer!!

Install:!curl -L http://cpanmin.us | perl - Dancer YAML Template !

!!

Awesome

Thank You!!!