Mojolicious::Guides::RUsernContributed Perl DocMojolicious::Guides::Routing(3)NAMEMojolicious::Guides::Routing - Routing
OVERVIEW
This document contains a simple and fun introduction to the Mojolicious
router and its underlying concepts.
CONCEPTS
Essentials every Mojolicious developer should know.
Dispatcher
The foundation of every web framework is a tiny black box connecting
incoming requests with code generating the appropriate response.
GET /user/show/1 -> $self->render(text => 'Sebastian!');
This black box is usually called a dispatcher. There are many
implementations using different strategies to establish these
connections, but pretty much all are based around mapping the requests
path to some kind of response generator.
/user/show/1 -> $self->render(text => 'Sebastian!');
/user/show/2 -> $self->render(text => 'Sara!');
/user/show/3 -> $self->render(text => 'Baerbel!');
/user/show/4 -> $self->render(text => 'Wolfgang!');
While it is very well possible to make all these connections static, it
is also rather inefficient. That's why regular expressions are
commonly used to make the dispatch process more dynamic.
qr|/user/show/(\d+)| -> $self->render(text => $users{$1});
Modern dispatchers have pretty much everything HTTP has to offer at
their disposal and can use many more variables than just the request
path, such as request method and headers like "Host", "User-Agent" and
"Accept".
GET /user/show/23 HTTP/1.1
Host: mojolicio.us
User-Agent: Mozilla/5.0 (compatible; Mojolicious; Perl)
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Routes
While regular expressions are quite powerful they also tend to be
unpleasant to look at and are generally overkill for ordinary path
matching.
qr|/user/show/(\d+)| -> $self->render(text => $users{$1});
This is where routes come into play, they have been designed from the
ground up to represent paths with placeholders.
/user/show/:id -> $self->render(text => $users{$id});
The only difference between a static path and the route above is the
":id" placeholder. One or more placeholders can be anywhere in the
route.
/user/:action/:id
A fundamental concept of the Mojolicious router is that extracted
placeholder values are turned into a hash.
/user/show/23 -> /user/:action/:id -> {action => 'show', id => 23}
This hash is basically the center of every Mojolicious application, you
will learn more about this later on. Internally routes get compiled to
regular expressions, so you can get the best of both worlds with a
little bit of experience.
/user/show/:id -> qr/(?-xism:^\/user\/show/([^\/\.]+))/
A trailing slash is always optional.
/user/show/23/ -> /user/:action/:id -> {action => 'show', id => 23}
Reversibility
One more huge advantage routes have over regular expressions is that
they are easily reversible, extracted placeholders can be turned back
into a path at any time.
/sebastian -> /:name -> {name => 'sebastian'}
{name => 'sebastian'} -> /:name -> /sebastian
Generic Placeholders
Generic placeholders are the simplest form of placeholders and match
all characters except "/" and ".".
/hello -> /:name/hello -> undef
/sebastian/23/hello -> /:name/hello -> undef
/sebastian.23/hello -> /:name/hello -> undef
/sebastian/hello -> /:name/hello -> {name => 'sebastian'}
/sebastian23/hello -> /:name/hello -> {name => 'sebastian23'}
/sebastian 23/hello -> /:name/hello -> {name => 'sebastian 23'}
A generic placeholder can be surrounded by parentheses to separate it
from the surrounding text.
/hello -> /(:name)hello -> undef
/sebastian/23hello -> /(:name)hello -> undef
/sebastian.23hello -> /(:name)hello -> undef
/sebastianhello -> /(:name)hello -> {name => 'sebastian'}
/sebastian23hello -> /(:name)hello -> {name => 'sebastian23'}
/sebastian 23hello -> /(:name)hello -> {name => 'sebastian 23'}
Wildcard Placeholders
Wildcard placeholders are just like generic placeholders, but match
absolutely everything.
/hello -> /*name/hello -> undef
/sebastian/23/hello -> /*name/hello -> {name => 'sebastian/23'}
/sebastian.23/hello -> /*name/hello -> {name => 'sebastian.23'}
/sebastian/hello -> /*name/hello -> {name => 'sebastian'}
/sebastian23/hello -> /*name/hello -> {name => 'sebastian23'}
/sebastian 23/hello -> /*name/hello -> {name => 'sebastian 23'}
Relaxed Placeholders
Relaxed placeholders are similar to the two placeholders above, but
always require parentheses and match all characters except "/".
/hello -> /(.name)/hello -> undef
/sebastian/23/hello -> /(.name)/hello -> undef
/sebastian.23/hello -> /(.name)/hello -> {name => 'sebastian.23'}
/sebastian/hello -> /(.name)/hello -> {name => 'sebastian'}
/sebastian23/hello -> /(.name)/hello -> {name => 'sebastian23'}
/sebastian 23/hello -> /(.name)/hello -> {name => 'sebastian 23'}
BASICS
Most commonly used features every Mojolicious developer should know
about.
Minimal Route
Every Mojolicious application has a router object you can use to
generate routes structures.
# Application
package MyApp;
use Mojo::Base 'Mojolicious';
sub startup {
my $self = shift;
# Router
my $r = $self->routes;
# Route
$r->route('/welcome')->to(controller => 'foo', action => 'welcome');
}
1;
The minimal static route above will load and instantiate the class
"MyApp::Foo" and call its "welcome" method.
# Controller
package MyApp::Foo;
use Mojo::Base 'Mojolicious::Controller';
# Action
sub welcome {
my $self = shift;
# Render response
$self->render(text => 'Hello there!');
}
1;
Routes are usually configured in the "startup" method of the
application class, but the router can be accessed from everywhere (even
at runtime).
Routing Destination
After you start a new route with the "route" method you can also give
it a destination in the form of a hash using the chained "to" method.
# /welcome -> {controller => 'foo', action => 'welcome'}
$r->route('/welcome')->to(controller => 'foo', action => 'welcome');
Now if the route matches an incoming request it will use the content of
this hash to try and find appropriate code to generate a response.
Stash
The generated hash of a matching route is actually the center of the
whole Mojolicious request cycle. We call it the stash, and it is
basically a global namespace that persists until a response has been
generated.
# /bye -> {controller => 'foo', action => 'bye', mymessage => 'Bye!'}
$r->route('/bye')
->to(controller => 'foo', action => 'bye', mymessage => 'Bye!');
There are a few stash values with special meaning, such as "controller"
and "action", but you can generally fill it with whatever data you need
to generate a response. Once dispatched the whole stash content can be
changed at any time.
sub bye {
my $self = shift;
# Get message from stash
my $message = $self->stash('mymessage');
# Change message in stash
$self->stash(mymessage => 'Welcome!');
}
Special Stash Values ("controller" and "action")
When the dispatcher sees "controller" and "action" values in the stash
it will always try to turn them into a class and method to dispatch to.
The "controller" value gets camelized and prefixed with a "namespace"
(defaulting to the applications class) while the action value is not
changed at all, because of this both values are case sensitive.
# Application
package MyApp;
use Mojo::Base 'Mojolicious';
sub startup {
my $self = shift;
# Router
my $r = $self->routes;
# /bye -> {controller => 'foo', action => 'bye'} -> MyApp::Foo->bye
$r->route('/bye')->to(controller => 'foo', action => 'bye');
}
1;
# Controller
package MyApp::Foo;
use Mojo::Base 'Mojolicious::Controller';
# Action
sub bye {
my $self = shift;
# Render response
$self->render(text => 'Good bye!');
}
1;
Controller classes are perfect for organizing code in larger projects.
There are more dispatch strategies, but because controllers are the
most commonly used ones they also got a special shortcut in the form of
"controller#action".
# /bye -> {controller => 'foo', action => 'bye', mymessage => 'Bye!'}
$r->route('/bye')->to('foo#bye', mymessage => 'Bye!');
During camelization "-" gets replaced with "::", this allows multi
level "controller" hierarchies.
# / -> {controller => 'foo-bar', action => 'hi'} -> MyApp::Foo::Bar->hi
$r->route('/')->to('foo-bar#hi');
Route To Class ("namespace")
From time to time you might want to dispatch to a whole different
"namespace".
# /bye -> MyApp::Controller::Foo->bye
$r->route('/bye')
->to(namespace => 'MyApp::Controller::Foo', action => 'bye');
The "controller" is always appended to the "namespace" if available.
# /bye -> MyApp::Controller::Foo->bye
$r->route('/bye')->to('foo#bye', namespace => 'MyApp::Controller');
You can also change the default namespace for all routes in the
application.
$r->namespace('MyApp::Controller');
Route To Callback ("cb")
You can use the "cb" stash value to bypass controllers and execute a
callback instead.
$r->route('/bye')->to(cb => sub {
my $self = shift;
$self->render(text => 'Good bye!');
});
This technique is the foundation of Mojolicious::Lite, you can learn
more about it from the included tutorial.
More Restrictive Placeholders
A very easy way to make placeholders more restrictive are alternatives,
you just make a list of possible values.
# /bender -> {controller => 'foo', action => 'bar', name => 'bender'}
# /leela -> {controller => 'foo', action => 'bar', name => 'leela'}
# /fry -> undef
$r->route('/:name', name => [qw/bender leela/])
->to(controller => 'foo', action => 'bar');
You can also adjust the regular expressions behind placeholders to
better suit your needs. Just make sure not to use "^" and "$" or
capturing groups "(...)", because placeholders become part of a larger
regular expression internally, "(?:...)" is fine though.
# /23 -> {controller => 'foo', action => 'bar', number => 23}
# /test -> undef
$r->route('/:number', number => qr/\d+/)
->to(controller => 'foo', action => 'bar');
# /23 -> undef
# /test -> {controller => 'foo', action => 'bar', name => 'test'}
$r->route('/:name', name => qr/[a-zA-Z]+/)
->to(controller => 'foo', action => 'bar');
This way you get easily readable routes and the raw power of regular
expressions.
Formats
File extensions like ".html" and ".txt" at the end of a route are
automatically detected and stored in the stash value "format".
# /foo -> {controller => 'foo', action => 'bar'}
# /foo.html -> {controller => 'foo', action => 'bar', format => 'html'}
# /foo.txt -> {controller => 'foo', action => 'bar', format => 'txt'}
$r->route('/foo')->to(controller => 'foo', action => 'bar');
This for example allows multiple templates for different formats to
share the same code. You can also mention a format in the route
pattern to only match one, just make sure the more specific routes go
first.
# /foo.txt -> {controller => 'foo', action => 'text', format => 'txt'}
$r->route('/foo.txt')->to(controller => 'foo', action => 'text');
# /foo -> {controller => 'foo', action => 'hyper'}
# /foo.html -> {controller => 'foo', action => 'hyper', format => 'html'}
$r->route('/foo')->to(controller => 'foo', action => 'hyper');
Restrictive placeholders can also be used for format detection.
# /foo.rss -> {controller => 'foo', action => 'feed', format => 'rss'}
# /foo.xml -> {controller => 'foo', action => 'feed', format => 'xml'}
# /foo.txt -> undef
$r->route('/foo', format => [qw/rss xml/])
->to(controller => 'foo', action => 'feed');
Or you can just disable format detection.
# /foo -> {controller => 'foo', action => 'bar'}
# /foo.html -> undef
$r->route('/foo', format => 0)->to(controller => 'foo', action => 'bar');
Placeholders And Destinations
Extracted placeholder values will simply redefine older stash values if
they already exist.
# /bye -> {controller => 'foo', action => 'bar', mymessage => 'bye'}
# /hey -> {controller => 'foo', action => 'bar', mymessage => 'hey'}
$r->route('/:mymessage')
->to(controller => 'foo', action => 'bar', mymessage => 'hi');
One more interesting effect, if a placeholder is at the end of a route
and there is already a stash value of the same name present, it
automatically becomes optional.
# / -> {controller => 'foo', action => 'bar', mymessage => 'hi'}
$r->route('/:mymessage')
->to(controller => 'foo', action => 'bar', mymessage => 'hi');
This is also the case if multiple placeholders are right after another
and not separated by other characters than "/".
# / -> {controller => 'foo', action => 'bar'}
# /users -> {controller => 'users', action => 'bar'}
# /users/list -> {controller => 'users', action => 'list'}
$r->route('/:controller/:action')
->to(controller => 'foo', action => 'bar');
Special stash values like "controller" and "action" can also be
placeholders, this allows for extremely flexible routes constructs.
Named Routes
Naming your routes will allow backreferencing in many kinds of helpers
throughout the whole framework.
# /foo/abc -> {controller => 'foo', action => 'bar', name => 'abc'}
$r->route('/foo/:name')->name('test')
->to(controller => 'foo', action => 'bar');
# Generate URL "/foo/abc" for route "test"
$self->url_for('test');
# Generate URL "/foo/sebastian" for route "test"
$self->url_for('test', name => 'sebastian');
Nameless routes get an automatically generated one assigned that is
simply equal to the route itself without non-word characters.
# /foo/bar ("foobar")
$r->route('/foo/bar')->to('test#stuff');
# Generate URL "/foo/bar"
$self->url_for('foobar');
To refer to the current route you can always use the reserved name
"current".
# Generate URL for current route
$self->url_for('current');
HTTP Methods
The "via" method of the route object allows only specific HTTP methods
to pass.
# GET /bye -> {controller => 'foo', action => 'bye'}
# POST /bye -> undef
# DELETE /bye -> undef
$r->route('/bye')->via('get')->to(controller => 'foo', action => 'bye');
# GET /bye -> {controller => 'foo', action => 'bye'}
# POST /bye -> {controller => 'foo', action => 'bye'}
# DELETE /bye -> undef
$r->route('/bye')->via(qw/get post/)
->to(controller => 'foo', action => 'bye');
Nested Routes
It is also possible to build tree structures from routes to remove
repetitive code. A route with children can't match on it's own though,
only the actual endpoints of these nested routes can.
# /foo -> undef
# /foo/bar -> {controller => 'foo', action => 'bar'}
my $foo = $r->route('/foo')->to(controller => 'foo');
$foo->route('/bar')->to(action => 'bar');
The stash will simply move from route to route and newer values
override old ones.
# /foo -> undef
# /foo/abc -> undef
# /foo/bar -> {controller => 'foo', action => 'bar'}
# /foo/baz -> {controller => 'foo', action => 'baz'}
# /foo/cde -> {controller => 'foo', action => 'abc'}
my $foo = $r->route('/foo')->to(controller => 'foo', action => 'abc');
$foo->route('/bar')->to(action => 'bar');
$foo->route('/baz')->to(action => 'baz');
$foo->route('/cde');
Waypoints
Waypoints are very similar to normal nested routes but can match even
if they have children.
# /foo -> {controller => 'foo', action => 'baz'}
# /foo/bar -> {controller => 'foo', action => 'bar'}
my $foo = $r->waypoint('/foo')->to(controller => 'foo', action => 'baz');
$foo->route('/bar')->to(action => 'bar');
All children will be ignored if a waypoint matches.
Bridges
Bridges unlike nested routes and waypoints always match and result in
additional dispatch cycles.
# /foo -> undef
# /foo/bar -> {controller => 'foo', action => 'baz'}
# {controller => 'foo', action => 'bar'}
my $foo = $r->bridge('/foo')->to(controller => 'foo', action => 'baz');
$foo->route('/bar')->to(action => 'bar');
The actual bridge code needs to return a true value or the dispatch
chain will be broken, this makes bridges a very powerful tool for
authentication.
# /foo -> undef
# /foo/bar -> {cb => sub {...}}
# {controller => 'foo', action => 'bar'}
my $foo = $r->bridge('/foo')->to(cb => sub {
my $self = shift;
# Authenticated
return 1 if $self->req->headers->header('X-Bender');
# Not authenticated
return;
});
$foo->route('/bar')->to(controller => 'foo', action => 'bar');
Mojolicious::Lite routes
Mojolicious::Lite routes are in fact just a small convenience layer
around everything described above and also part of the normal router.
# GET /foo -> {controller => 'foo', action => 'abc'}
$r->get('/foo')->to(controller => 'foo', action => 'abc');
This makes the process of growing your Mojolicious::Lite prototypes
into full Mojolicious applications very straightforward.
# POST /bar
$r->post('/bar' => sub {
my $self = shift;
$self->render(text => 'Just like a Mojolicious::Lite action!');
});
Even the more abstract concepts are available.
# GET /yada
# POST /yada
my $yada = $r->under('/yada');
$yada->get(sub {
my $self = shift;
$self->render(text => 'Hello!');
});
$yada->post(sub {
my $self = shift;
$self->render(text => 'Go away!');
});
Shortcuts
You can also add your own shortcuts to make route generation more
expressive.
# Simple "resource" shortcut
$r->add_shortcut(resource => sub {
my ($r, $name) = @_;
# Generate "/$name" route
my $resource = $r->route("/$name")->to("$name#");
# Handle POST requests
$resource->post->to('#create')->name("create_$name");
# Handle GET requests
$resource->get->to('#show')->name("show_$name");
return $resource;
});
# POST /user -> {controller => 'user', action => 'create'}
# GET /user -> {controller => 'user', action => 'show'}
$r->resource('user');
Shortcuts can lead to anything, routes, bridges or maybe even both.
And watch out for quicksand!
ADVANCED
Less commonly used and more powerful features.
Conditions
Sometimes you might need a little more power, for example to check the
"User-Agent" header in multiple routes. This is where conditions come
into play, they are basically router plugins.
# Simple "User-Agent" condition
$r->add_condition(
agent => sub {
my ($r, $c, $captures, $pattern) = @_;
# User supplied regular expression
return unless $pattern && ref $pattern eq 'Regexp';
# Match "User-Agent" header and return true on success
my $agent = $c->req->headers->user_agent;
return 1 if $agent && $agent =~ $pattern;
# No success
return;
}
);
# /firefox_only (Firefox) -> {controller => 'foo', action => 'bar'}
$r->route('/firefox_only')->over(agent => qr/Firefox/)
->to(controller => 'foo', action => 'bar');
The method "add_condition" registers the new condition in the router
while "over" actually applies it to the route.
Condition Plugins
You can also package your conditions as reusable plugins.
# Plugin
package Mojolicious::Plugin::WerewolfCondition;
use Mojo::Base 'Mojolicious::Plugin';
use Astro::MoonPhase;
sub register {
my ($self, $app) = @_;
# Add "werewolf" condition
$app->routes->add_condition(
werewolf => sub {
my ($r, $c, $captures, $days) = @_;
# Keep the werewolfs out!
return if abs(14 - (phase(time))[2]) > ($days / 2);
# It's ok, no werewolf
return 1;
}
);
}
1;
Now just load the plugin and you are ready to use the condition in all
your applications.
# Application
package MyApp;
use Mojo::Base 'Mojolicious';
sub startup {
my $self = shift;
# Plugin
$self->plugin('WerewolfCondition');
# Routes
my $r = $self->routes;
# /hideout (keep them out for 4 days after full moon)
$r->route('/hideout')->over(werewolf => 4)
->to(controller => 'foo', action => 'bar');
}
1;
Embedding Applications
You can easily embed whole applications simply by using them instead of
a controller. This allows for example the use of the Mojolicious::Lite
domain specific language in normal Mojolicious controllers.
# Controller
package MyApp::Bar;
use Mojolicious::Lite;
# /hello
get '/hello' => sub {
my $self = shift;
my $name = $self->param('name');
$self->render(text => "Hello $name!");
};
1;
With the "detour" method which is very similar to "to", you can allow
the route to partially match and use only the remaining path in the
embedded application.
# /foo/*
$r->route('/foo')->detour('bar#', name => 'Mojo');
A minimal embeddable application is nothing more than a subclass of
Mojo, containing a "handler" method accepting Mojolicious::Controller
objects.
package MyApp::Bar;
use Mojo::Base 'Mojo';
sub handler {
my ($self, $c) = @_;
$c->res->code(200);
my $name = $c->param('name');
$c->res->body("Hello $name!");
}
1;
You can also just use Mojolicious::Plugin::Mount to mount whole self-
contained applications under a prefix.
use Mojolicious::Lite;
# Whole application mounted under "/prefix"
plugin Mount => {'/prefix' => '/home/sri/myapp.pl'};
# Normal route
get '/' => sub { shift->render_text('Hello World!') };
app->start;
Application Plugins
Embedding Mojolicious applications is easy, but it gets even easier if
you package the whole thing as a self contained reusable plugin.
# Plugin
package Mojolicious::Plugin::MyEmbeddedApp;
use Mojo::Base 'Mojolicious::Plugin';
sub register {
my ($self, $app) = @_;
# Automatically add route
$app->routes->route('/foo')->detour(app => EmbeddedApp::app());
}
package EmbeddedApp;
use Mojolicious::Lite;
get '/bar' => 'bar';
1;
__DATA__
@@ bar.html.ep
Hello World!
The "app" stash value can be used for already instantiated
applications. Now just load the plugin and you're done.
# Application
package MyApp;
use Mojo::Base 'Mojolicious';
sub startup {
my $self = shift;
# Plugin
$self->plugin('MyEmbeddedApp');
}
1;
WebSockets
You can restrict access to WebSocket handshakes using the "websocket"
method.
# /ws (WebSocket handshake)
$r->websocket('/echo')->to(controller => 'foo', action => 'echo');
# Controller
package MyApp::Foo;
use Mojo::Base 'Mojolicious::Controller';
# Action
sub echo {
my $self = shift;
$self->on_message(sub {
my ($self, $message) = @_;
$self->send_message("echo: $message");
});
}
1;
IRIs
IRIs are handled transparently, that means paths are guaranteed to be
unescaped and decoded to Perl characters.
use utf8;
# /X (unicode snowman) -> {controller => 'foo', action => 'snowman'}
$r->route('/X')->to(controller => 'foo', action => 'snowman');
Just don't forget to use the utf8 pragma or you'll make the unicode
snowman very sad.
Introspection
The "routes" command can be used from the command line to list all
available routes together with name and underlying regular expressions.
$ script/myapp routes
/foo/:name GET fooname (?-xism:^/foo/([^\/\.]+))
/baz/*everything POST bazeverything (?-xism:^/baz/(.+))
/bar/(.test) * bartest (?-xism:^/bar/([^\/]+))
MORE
You can continue with Mojolicious::Guides now or take a look at the
Mojolicious wiki <http://github.com/kraih/mojo/wiki>, which contains a
lot more documentation and examples by many different authors.
perl v5.14.1 2011-09-10 Mojolicious::Guides::Routing(3)
