NAME¶
Mojolicious::Guides::Cookbook - Cookbook
OVERVIEW¶
This document contains many fun recipes for cooking with Mojolicious.
DEPLOYMENT¶
Getting Mojolicious and Mojolicious::Lite applications running on different
platforms. Note that many real-time web features are based on the Mojo::IOLoop
event loop, and therefore require one of the built-in web servers to be able
to use them to their full potential.
Built-in web server¶
Mojolicious contains a very portable non-blocking I/O HTTP and WebSocket server
with Mojo::Server::Daemon. It is usually used during development and in the
construction of more advanced web servers, but is solid and fast enough for
small to mid sized applications.
$ ./script/myapp daemon
Server available at http://127.0.0.1:3000.
It is available to every application through the command
Mojolicious::Command::daemon, which has many configuration options and is
known to work on every platform Perl works on with its single-process
architecture.
$ ./script/myapp daemon -h
...List of available options...
Another huge advantage is that it supports TLS and WebSockets out of the box, a
development certificate for testing purposes is built right in, so it just
works, but you can specify all listen locations supported by
"listen" in Mojo::Server::Daemon.
$ ./script/myapp daemon -l https://[::]:3000
Server available at https://[::]:3000.
On UNIX platforms you can also add preforking and switch to a multi-process
architecture with Mojolicious::Command::prefork, to take advantage of multiple
CPU cores and copy-on-write.
$ ./script/myapp prefork
Server available at http://127.0.0.1:3000.
Since all built-in web servers are based on the Mojo::IOLoop event loop, they
scale best with non-blocking operations. But if your application for some
reason needs to perform many blocking operations, you can improve performance
by increasing the number of worker processes and decreasing the number of
concurrent connections each worker is allowed to handle (often as low as 1).
$ ./script/myapp prefork -m production -w 10 -c 1
Server available at http://127.0.0.1:3000.
Your application is preloaded in the manager process during startup, to run code
whenever a new worker process has been forked you can use
"next_tick" in Mojo::IOLoop.
use Mojolicious::Lite;
Mojo::IOLoop->next_tick(sub {
app->log->info("Worker $$ star...ALL GLORY TO THE HYPNOTOAD!");
});
get '/' => {text => 'Hello Wor...ALL GLORY TO THE HYPNOTOAD!'};
app->start;
Morbo¶
After reading the Mojolicious::Lite tutorial, you should already be familiar
with Mojo::Server::Morbo.
Mojo::Server::Morbo
+- Mojo::Server::Daemon
It is basically a restarter that forks a new Mojo::Server::Daemon web server
whenever a file in your project changes, and should therefore only be used
during development.
$ morbo ./script/myapp
Server available at http://127.0.0.1:3000.
Hypnotoad¶
For bigger applications Mojolicious contains the UNIX optimized preforking web
server Mojo::Server::Hypnotoad, which can take advantage of multiple CPU cores
and copy-on-write to scale up to thousands of concurrent client connections.
Mojo::Server::Hypnotoad
|- Mojo::Server::Daemon [1]
|- Mojo::Server::Daemon [2]
|- Mojo::Server::Daemon [3]
+- Mojo::Server::Daemon [4]
It is based on the Mojo::Server::Prefork web server, which adds preforking to
Mojo::Server::Daemon, but optimized specifically for production environments
out of the box.
$ hypnotoad ./script/myapp
Server available at http://127.0.0.1:8080.
It automatically sets the operating mode to "production" and you can
tweak many configuration settings right from within your application with
"config" in Mojo, for a full list see "SETTINGS" in
Mojo::Server::Hypnotoad.
use Mojolicious::Lite;
app->config(hypnotoad => {listen => ['http://*:80']});
get '/' => {text => 'Hello Wor...ALL GLORY TO THE HYPNOTOAD!'};
app->start;
Or just add a "hypnotoad" section to your Mojolicious::Plugin::Config
or Mojolicious::Plugin::JSONConfig configuration file.
# myapp.conf
{
hypnotoad => {
listen => ['https://*:443?cert=/etc/server.crt&key=/etc/server.key'],
workers => 10
}
};
But one of its biggest advantages is the support for effortless zero downtime
software upgrades (hot deployment). That means you can upgrade Mojolicious,
Perl or even system libraries at runtime without ever stopping the server or
losing a single incoming connection, just by running the command above again.
$ hypnotoad ./script/myapp
Starting hot deployment for Hypnotoad server 31841.
You might also want to enable proxy support if you're using Hypnotoad behind a
reverse proxy. This allows Mojolicious to automatically pick up the
"X-Forwarded-For" and "X-Forwarded-Proto" headers.
# myapp.conf
{hypnotoad => {proxy => 1}};
Zero downtime software upgrades¶
Hypnotoad makes zero downtime software upgrades (hot deployment) very simple, as
you can see above, but on modern operating systems that support the
"SO_REUSEPORT" socket option, there is also another method available
that works with all built-in web servers.
$ ./script/myapp prefork -P /tmp/first.pid -l http://*:8080?reuse=1
Server available at http://127.0.0.1:8080.
All you have to do is start a second web server listening to the same port and
stop the first web server gracefully afterwards.
$ ./script/myapp prefork -P /tmp/second.pid -l http://*:8080?reuse=1
Server available at http://127.0.0.1:8080.
$ kill -s TERM `cat /tmp/first.pid`
Just remember that both web servers need to be started with the
"reuse" parameter.
Nginx¶
One of the most popular setups these days is Hypnotoad behind an Nginx
<
http://nginx.org> reverse proxy, which even supports WebSockets in
newer versions.
upstream myapp {
server 127.0.0.1:8080;
}
server {
listen 80;
server_name localhost;
location / {
proxy_pass http://myapp;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto "http";
}
}
Apache/mod_proxy¶
Another good reverse proxy is Apache <
http://httpd.apache.org> with
"mod_proxy", the configuration looks quite similar to the Nginx one
above.
<VirtualHost *:80>
ServerName localhost
<Proxy *>
Order deny,allow
Allow from all
</Proxy>
ProxyRequests Off
ProxyPreserveHost On
ProxyPass / http://localhost:8080/ keepalive=On
ProxyPassReverse / http://localhost:8080/
RequestHeader set X-Forwarded-Proto "http"
</VirtualHost>
Apache/CGI¶
"CGI" is supported out of the box and your Mojolicious application
will automatically detect that it is executed as a "CGI" script.
It's use in production environments is discouraged though, because as a result
of how "CGI" works, it is very slow and many web servers are making
it exceptionally hard to configure properly.
ScriptAlias / /home/sri/myapp/script/myapp/
PSGI/Plack¶
PSGI is an interface between Perl web frameworks and web servers, and Plack is a
Perl module and toolkit that contains PSGI middleware, helpers and adapters to
web servers. PSGI and Plack are inspired by Python's WSGI and Ruby's Rack.
Mojolicious applications are ridiculously simple to deploy with Plack.
$ plackup ./script/myapp
Plack provides many server and protocol adapters for you to choose from, such as
"FCGI", "uWSGI" and "mod_perl".
$ plackup ./script/myapp -s FCGI -l /tmp/myapp.sock
The "MOJO_REVERSE_PROXY" environment variable can be used to enable
proxy support, this allows Mojolicious to automatically pick up the
"X-Forwarded-For" and "X-Forwarded-Proto" headers.
$ MOJO_REVERSE_PROXY=1 plackup ./script/myapp
If an older server adapter is unable to correctly detect the application home
directory, you can simply use the "MOJO_HOME" environment variable.
$ MOJO_HOME=/home/sri/myapp plackup ./script/myapp
There is no need for a ".psgi" file, just point the server adapter at
your application script, it will automatically act like one if it detects the
presence of a "PLACK_ENV" environment variable.
Plack middleware¶
Wrapper scripts like "myapp.fcgi" are a great way to separate
deployment and application logic.
#!/usr/bin/env plackup -s FCGI
use Plack::Builder;
builder {
enable 'Deflater';
require './script/myapp';
};
Mojo::Server::PSGI can be used directly to load and customize applications in
the wrapper script.
#!/usr/bin/env plackup -s FCGI
use Mojo::Server::PSGI;
use Plack::Builder;
builder {
enable 'Deflater';
my $server = Mojo::Server::PSGI->new;
$server->load_app('./script/myapp');
$server->app->config(foo => 'bar');
$server->to_psgi_app;
};
But you could even use middleware right in your application.
use Mojolicious::Lite;
use Plack::Builder;
get '/welcome' => sub {
my $c = shift;
$c->render(text => 'Hello Mojo!');
};
builder {
enable 'Deflater';
app->start;
};
Rewriting¶
Sometimes you might have to deploy your application in a blackbox environment
where you can't just change the server configuration or behind a reverse proxy
that passes along additional information with "X-*" headers. In such
cases you can use the hook "before_dispatch" in Mojolicious to
rewrite incoming requests.
# Change scheme if "X-Forwarded-HTTPS" header is set
$app->hook(before_dispatch => sub {
my $c = shift;
$c->req->url->base->scheme('https')
if $c->req->headers->header('X-Forwarded-HTTPS');
});
Since reverse proxies generally don't pass along information about path prefixes
your application might be deployed under, rewriting the base path of incoming
requests is also quite common.
# Move first part and slash from path to base path in production mode
$app->hook(before_dispatch => sub {
my $c = shift;
push @{$c->req->url->base->path->trailing_slash(1)},
shift @{$c->req->url->path->leading_slash(0)};
}) if $app->mode eq 'production';
Mojo::URL objects are very easy to manipulate, just make sure that the URL
("foo/bar?baz=yada"), which represents the routing destination, is
always relative to the base URL ("
http://example.com/myapp/"), which
represents the deployment location of your application.
Application embedding¶
From time to time you might want to reuse parts of Mojolicious applications like
configuration files, database connection or helpers for other scripts, with
this little Mojo::Server based mock server you can just embed them.
use Mojo::Server;
# Load application with mock server
my $server = Mojo::Server->new;
my $app = $server->load_app('./myapp.pl');
# Access fully initialized application
say for @{$app->static->paths};
say $app->config->{secret_identity};
say $app->dumper({just => 'a helper test'});
say $app->build_controller->render_to_string(template => 'foo');
The plugin Mojolicious::Plugin::Mount uses this functionality to allow you to
combine multiple applications into one and deploy them together.
use Mojolicious::Lite;
plugin Mount => {'test1.example.com' => '/home/sri/myapp1.pl'};
plugin Mount => {'test2.example.com' => '/home/sri/myapp2.pl'};
app->start;
Web server embedding¶
You can also use "one_tick" in Mojo::IOLoop to embed the built-in web
server Mojo::Server::Daemon into alien environments like foreign event loops
that for some reason can't just be integrated with a new reactor backend.
use Mojolicious::Lite;
use Mojo::IOLoop;
use Mojo::Server::Daemon;
# Normal action
get '/' => {text => 'Hello World!'};
# Connect application with web server and start accepting connections
my $daemon
= Mojo::Server::Daemon->new(app => app, listen => ['http://*:8080']);
$daemon->start;
# Call "one_tick" repeatedly from the alien environment
Mojo::IOLoop->one_tick while 1;
REAL-TIME WEB¶
The real-time web is a collection of technologies that include Comet (long
polling), EventSource and WebSockets, which allow content to be pushed to
consumers with long-lived connections as soon as it is generated, instead of
relying on the more traditional pull model. All built-in web servers use
non-blocking I/O and are based on the Mojo::IOLoop event loop, which provides
many very powerful features that allow real-time web applications to scale up
to thousands of concurrent client connections.
Backend web services¶
Since Mojo::UserAgent is also based on the Mojo::IOLoop event loop, it won't
block the built-in web servers when used non-blocking, even for high latency
backend web services.
use Mojolicious::Lite;
# Search MetaCPAN for "mojolicious"
get '/' => sub {
my $c = shift;
$c->ua->get('api.metacpan.org/v0/module/_search?q=mojolicious' => sub {
my ($ua, $tx) = @_;
$c->render('metacpan', hits => $tx->res->json->{hits}{hits});
});
};
app->start;
__DATA__
@@ metacpan.html.ep
<!DOCTYPE html>
<html>
<head><title>MetaCPAN results for "mojolicious"</title></head>
<body>
% for my $hit (@$hits) {
<p><%= $hit->{_source}{release} %></p>
% }
</body>
</html>
Multiple events such as concurrent requests can be easily synchronized with
"delay" in Mojolicious::Plugin::DefaultHelpers, which can help you
avoid deep nested closures and memory leaks that often result from
continuation-passing style.
use Mojolicious::Lite;
use Mojo::URL;
# Search MetaCPAN for "mojo" and "minion"
get '/' => sub {
my $c = shift;
# Prepare response in two steps
$c->delay(
# Concurrent requests
sub {
my $delay = shift;
my $url = Mojo::URL->new('api.metacpan.org/v0/module/_search');
$url->query({sort => 'date:desc'});
$c->ua->get($url->clone->query({q => 'mojo'}) => $delay->begin);
$c->ua->get($url->clone->query({q => 'minion'}) => $delay->begin);
},
# Delayed rendering
sub {
my ($delay, $mojo, $minion) = @_;
$c->render(json => {
mojo => $mojo->res->json('/hits/hits/0/_source/release'),
minion => $minion->res->json('/hits/hits/0/_source/release')
});
}
);
};
app->start;
Timers¶
Another primary feature of the event loop are timers, which are created with
"timer" in Mojo::IOLoop and can for example be used to delay
rendering of a response, and unlike "sleep", won't block any other
requests that might be processed concurrently.
use Mojolicious::Lite;
use Mojo::IOLoop;
# Wait 3 seconds before rendering a response
get '/' => sub {
my $c = shift;
Mojo::IOLoop->timer(3 => sub {
$c->render(text => 'Delayed by 3 seconds!');
});
};
app->start;
Recurring timers created with "recurring" in Mojo::IOLoop are slightly
more powerful, but need to be stopped manually, or they would just keep
getting emitted.
use Mojolicious::Lite;
use Mojo::IOLoop;
# Count to 5 in 1 second steps
get '/' => sub {
my $c = shift;
# Start recurring timer
my $i = 1;
my $id = Mojo::IOLoop->recurring(1 => sub {
$c->write_chunk($i);
$c->finish if $i++ == 5;
});
# Stop recurring timer
$c->on(finish => sub { Mojo::IOLoop->remove($id) });
};
app->start;
Timers are not tied to a specific request or connection, and can even be created
at startup time.
use Mojolicious::Lite;
use Mojo::IOLoop;
# Check title in the background every 10 seconds
my $title = 'Got no title yet.';
Mojo::IOLoop->recurring(10 => sub {
app->ua->get('http://mojolicio.us' => sub {
my ($ua, $tx) = @_;
$title = $tx->res->dom->at('title')->text;
});
});
# Show current title
get '/' => sub {
my $c = shift;
$c->render(json => {title => $title});
};
app->start;
Just remember that all events are processed cooperatively, so your callbacks
shouldn't block for too long.
Exceptions in events¶
Since timers and other non-blocking operations are running solely in the event
loop, outside of the application, exceptions that get thrown in callbacks
can't get caught and handled automatically. But you can handle them manually
by subscribing to the event "error" in Mojo::Reactor or catching
them inside the callback.
use Mojolicious::Lite;
use Mojo::IOLoop;
# Forward error messages to the application log
Mojo::IOLoop->singleton->reactor->on(error => sub {
my ($reactor, $err) = @_;
app->log->error($err);
});
# Exception only gets logged (and connection times out)
get '/connection_times_out' => sub {
my $c = shift;
Mojo::IOLoop->timer(2 => sub {
die 'This request will not be getting a response';
});
};
# Exception gets caught and handled
get '/catch_exception' => sub {
my $c = shift;
Mojo::IOLoop->timer(2 => sub {
eval { die 'This request will be getting a response' };
$c->reply->exception($@) if $@;
});
};
app->start;
A default subscriber that turns all errors into warnings will usually be added
by Mojo::IOLoop as a fallback.
Mojo::IOLoop->singleton->reactor->unsubscribe('error');
During development or for applications where crashing is simply preferable, you
can also make every exception that gets thrown in a callback fatal by removing
all of its subscribers.
WebSocket web service¶
The WebSocket protocol offers full bi-directional low-latency communication
channels between clients and servers. Receive messages just by subscribing to
events such as "message" in Mojo::Transaction::WebSocket with the
method "on" in Mojolicious::Controller and return them with
"send" in Mojolicious::Controller.
use Mojolicious::Lite;
# Template with browser-side code
get '/' => 'index';
# WebSocket echo service
websocket '/echo' => sub {
my $c = shift;
# Opened
$c->app->log->debug('WebSocket opened.');
# Increase inactivity timeout for connection a bit
$c->inactivity_timeout(300);
# Incoming message
$c->on(message => sub {
my ($c, $msg) = @_;
$c->send("echo: $msg");
});
# Closed
$c->on(finish => sub {
my ($c, $code, $reason) = @_;
$c->app->log->debug("WebSocket closed with status $code.");
});
};
app->start;
__DATA__
@@ index.html.ep
<!DOCTYPE html>
<html>
<head><title>Echo</title></head>
<body>
<script>
var ws = new WebSocket('<%= url_for('echo')->to_abs %>');
// Incoming messages
ws.onmessage = function(event) {
document.body.innerHTML += event.data + '<br/>';
};
// Outgoing messages
window.setInterval(function () { ws.send('Hello Mojo!') }, 1000);
</script>
</body>
</html>
The event "finish" in Mojo::Transaction::WebSocket will be emitted
right after the WebSocket connection has been closed.
$c->tx->with_compression;
You can activate "permessage-deflate" compression with
"with_compression" in Mojo::Transaction::WebSocket, this can result
in much better performance, but also increases memory usage by up to 300KB per
connection.
Testing WebSocket web services¶
While the message flow on WebSocket connections can be rather dynamic, it more
often than not is quite predictable, which allows this rather pleasant
Test::Mojo API to be used.
use Test::More;
use Test::Mojo;
# Include application
use FindBin;
require "$FindBin::Bin/../echo.pl";
# Test echo web service
my $t = Test::Mojo->new;
$t->websocket_ok('/echo')
->send_ok('Hello Mojo!')
->message_ok
->message_is('echo: Hello Mojo!')
->finish_ok;
# Test JSON web service
$t->websocket_ok('/echo.json')
->send_ok({json => {test => [1, 2, 3]}})
->message_ok
->json_message_is('/test', [1, 2, 3])
->finish_ok;
done_testing();
EventSource web service¶
EventSource is a special form of long polling where you can use
"write" in Mojolicious::Controller to directly send DOM events from
servers to clients. It is uni-directional, that means you will have to use
Ajax requests for sending data from clients to servers, the advantage however
is low infrastructure requirements, since it reuses the HTTP protocol for
transport.
use Mojolicious::Lite;
# Template with browser-side code
get '/' => 'index';
# EventSource for log messages
get '/events' => sub {
my $c = shift;
# Increase inactivity timeout for connection a bit
$c->inactivity_timeout(300);
# Change content type
$c->res->headers->content_type('text/event-stream');
# Subscribe to "message" event and forward "log" events to browser
my $cb = $c->app->log->on(message => sub {
my ($log, $level, @lines) = @_;
$c->write("event:log\ndata: [$level] @lines\n\n");
});
# Unsubscribe from "message" event again once we are done
$c->on(finish => sub {
my $c = shift;
$c->app->log->unsubscribe(message => $cb);
});
};
app->start;
__DATA__
@@ index.html.ep
<!DOCTYPE html>
<html>
<head><title>LiveLog</title></head>
<body>
<script>
var events = new EventSource('<%= url_for 'events' %>');
// Subscribe to "log" event
events.addEventListener('log', function(event) {
document.body.innerHTML += event.data + '<br/>';
}, false);
</script>
</body>
</html>
The event "message" in Mojo::Log will be emitted for every new log
message and the event "finish" in Mojo::Transaction right after the
transaction has been finished.
Streaming multipart uploads¶
Mojolicious contains a very sophisticated event system based on
Mojo::EventEmitter, with ready-to-use events on almost all layers, and which
can be combined to solve some of hardest problems in web development.
use Mojolicious::Lite;
use Scalar::Util 'weaken';
# Intercept multipart uploads and log each chunk received
hook after_build_tx => sub {
my $tx = shift;
# Subscribe to "upgrade" event to indentify multipart uploads
weaken $tx;
$tx->req->content->on(upgrade => sub {
my ($single, $multi) = @_;
return unless $tx->req->url->path->contains('/upload');
# Subscribe to "part" event to find the right one
$multi->on(part => sub {
my ($multi, $single) = @_;
# Subscribe to "body" event of part to make sure we have all headers
$single->on(body => sub {
my $single = shift;
# Make sure we have the right part and replace "read" event
return unless $single->headers->content_disposition =~ /example/;
$single->unsubscribe('read')->on(read => sub {
my ($single, $bytes) = @_;
# Log size of every chunk we receive
app->log->debug(length($bytes) . ' bytes uploaded.');
});
});
});
});
};
# Upload form in DATA section
get '/' => 'index';
# Streaming multipart upload
post '/upload' => {text => 'Upload was successful.'};
app->start;
__DATA__
@@ index.html.ep
<!DOCTYPE html>
<html>
<head><title>Streaming multipart upload</title></head>
<body>
%= form_for upload => (enctype => 'multipart/form-data') => begin
%= file_field 'example'
%= submit_button 'Upload'
% end
</body>
</html>
Event loops¶
Internally the Mojo::IOLoop event loop can use multiple reactor backends, EV for
example will be automatically used if installed. Which in turn allows other
event loops like AnyEvent to just work.
use Mojolicious::Lite;
use EV;
use AnyEvent;
# Wait 3 seconds before rendering a response
get '/' => sub {
my $c = shift;
my $w;
$w = AE::timer 3, 0, sub {
$c->render(text => 'Delayed by 3 seconds!');
undef $w;
};
};
app->start;
Who actually controls the event loop backend is not important.
use Mojo::UserAgent;
use EV;
use AnyEvent;
# Search MetaCPAN for "mojolicious"
my $cv = AE::cv;
my $ua = Mojo::UserAgent->new;
$ua->get('api.metacpan.org/v0/module/_search?q=mojolicious' => sub {
my ($ua, $tx) = @_;
$cv->send($tx->res->json('/hits/hits/0/_source/release'));
});
say $cv->recv;
You could for example just embed the built-in web server into an AnyEvent
application.
use Mojolicious::Lite;
use Mojo::Server::Daemon;
use EV;
use AnyEvent;
# Normal action
get '/' => {text => 'Hello World!'};
# Connect application with web server and start accepting connections
my $daemon
= Mojo::Server::Daemon->new(app => app, listen => ['http://*:8080']);
$daemon->start;
# Let AnyEvent take control
AE::cv->recv;
USER AGENT¶
When we say Mojolicious is a web framework we actually mean it, with
Mojo::UserAgent there's a full featured HTTP and WebSocket user agent built
right in.
Web scraping¶
Scraping information from web sites has never been this much fun before. The
built-in HTML/XML parser Mojo::DOM is accessible through "dom" in
Mojo::Message and supports all CSS selectors that make sense for a standalone
parser, it can be a very powerful tool especially for testing web application.
use Mojo::UserAgent;
# Fetch web site
my $ua = Mojo::UserAgent->new;
my $tx = $ua->get('mojolicio.us/perldoc');
# Extract title
say 'Title: ', $tx->res->dom->at('head > title')->text;
# Extract headings
$tx->res->dom('h1, h2, h3')->each(sub { say 'Heading: ', shift->all_text });
# Visit all nodes recursively to extract more than just text
for my $n ($tx->res->dom->all_contents->each) {
# Text or CDATA node
print $n->content if $n->node eq 'text' || $n->node eq 'cdata';
# Also include alternate text for images
print $n->{alt} if $n->node eq 'tag' && $n->type eq 'img';
}
For a full list of available CSS selectors see "SELECTORS" in
Mojo::DOM::CSS.
JSON web services¶
Most web services these days are based on the JSON data-interchange format.
That's why Mojolicious comes with the possibly fastest pure-Perl
implementation Mojo::JSON built right in, it is accessible through
"json" in Mojo::Message.
use Mojo::UserAgent;
use Mojo::URL;
# Fresh user agent
my $ua = Mojo::UserAgent->new;
# Search MetaCPAN for "mojolicious" and list latest releases
my $url = Mojo::URL->new('http://api.metacpan.org/v0/release/_search');
$url->query({q => 'mojolicious', sort => 'date:desc'});
for my $hit (@{$ua->get($url)->res->json->{hits}{hits}}) {
say "$hit->{_source}{name} ($hit->{_source}{author})";
}
Basic authentication¶
You can just add username and password to the URL, an "Authorization"
header will be automatically generated.
use Mojo::UserAgent;
my $ua = Mojo::UserAgent->new;
say $ua->get('https://sri:secret@example.com/hideout')->res->body;
Decorating followup requests¶
Mojo::UserAgent can automatically follow redirects, the event "start"
in Mojo::UserAgent allows you direct access to each transaction right after
they have been initialized and before a connection gets associated with them.
use Mojo::UserAgent;
# User agent following up to 10 redirects
my $ua = Mojo::UserAgent->new(max_redirects => 10);
# Add a witty header to every request
$ua->on(start => sub {
my ($ua, $tx) = @_;
$tx->req->headers->header('X-Bender' => 'Bite my shiny metal ass!');
say 'Request: ', $tx->req->url->clone->to_abs;
});
# Request that will most likely get redirected
say 'Title: ', $ua->get('google.com')->res->dom->at('head > title')->text;
This even works for proxy "CONNECT" requests.
Content generators¶
Content generators can be registered with "add_generator" in
Mojo::UserAgent::Transactor to generate the same type of content repeatedly
for multiple requests.
use Mojo::UserAgent;
use Mojo::Asset::File;
# Add "stream" generator
my $ua = Mojo::UserAgent->new;
$ua->transactor->add_generator(stream => sub {
my ($transactor, $tx, $path) = @_;
$tx->req->content->asset(Mojo::Asset::File->new(path => $path));
});
# Send multiple files streaming via PUT and POST
$ua->put('http://example.com/upload' => stream => '/home/sri/mojo.png');
$ua->post('http://example.com/upload' => stream => '/home/sri/minion.png');
The "json" and "form" content generators are always
available.
use Mojo::UserAgent;
# Send "application/json" content via PATCH
my $ua = Mojo::UserAgent->new;
my $tx = $ua->patch('http://api.example.com' => json => {foo => 'bar'});
# Send query parameters via GET
my $tx2 = $ua->get('http://search.example.com' => form => {q => 'test'});
# Send "application/x-www-form-urlencoded" content via POST
my $tx3 = $ua->post('http://search.example.com' => form => {q => 'test'});
# Send "multipart/form-data" content via PUT
my $tx4 = $ua->put('http://upload.example.com' =>
form => {test => {content => 'Hello World!'}});
For more information about available content generators see also "tx"
in Mojo::UserAgent::Transactor.
Large file downloads¶
When downloading large files with Mojo::UserAgent you don't have to worry about
memory usage at all, because it will automatically stream everything above
250KB into a temporary file, which can then be moved into a permanent file
with "move_to" in Mojo::Asset::File.
use Mojo::UserAgent;
# Lets fetch the latest Mojolicious tarball
my $ua = Mojo::UserAgent->new(max_redirects => 5);
my $tx = $ua->get('https://www.github.com/kraih/mojo/tarball/master');
$tx->res->content->asset->move_to('mojo.tar.gz');
To protect you from excessively large files there is also a limit of 10MB by
default, which you can tweak with the attribute "max_message_size"
in Mojo::Message or "MOJO_MAX_MESSAGE_SIZE" environment variable.
# Increase limit to 1GB
$ENV{MOJO_MAX_MESSAGE_SIZE} = 1073741824;
Large file upload¶
Uploading a large file is even easier.
use Mojo::UserAgent;
# Upload file via POST and "multipart/form-data"
my $ua = Mojo::UserAgent->new;
$ua->post('example.com/upload' =>
form => {image => {file => '/home/sri/hello.png'}});
And once again you don't have to worry about memory usage, all data will be
streamed directly from the file.
Streaming response¶
Receiving a streaming response can be really tricky in most HTTP clients, but
Mojo::UserAgent makes it actually easy.
use Mojo::UserAgent;
# Build a normal transaction
my $ua = Mojo::UserAgent->new;
my $tx = $ua->build_tx(GET => 'http://example.com');
# Accept response of indefinite size
$tx->res->max_message_size(0);
# Replace "read" events to disable default content parser
$tx->res->content->unsubscribe('read')->on(read => sub {
my ($content, $bytes) = @_;
say "Streaming: $bytes";
});
# Process transaction
$tx = $ua->start($tx);
The event "read" in Mojo::Content will be emitted for every chunk of
data that is received, even "chunked" encoding and gzip compression
will be handled transparently if necessary.
Streaming request¶
Sending a streaming request is almost just as easy.
use Mojo::UserAgent;
# Build a normal transaction
my $ua = Mojo::UserAgent->new;
my $tx = $ua->build_tx(GET => 'http://example.com');
# Prepare body
my $body = 'Hello world!';
$tx->req->headers->content_length(length $body);
# Start writing directly with a drain callback
my $drain;
$drain = sub {
my $content = shift;
my $chunk = substr $body, 0, 1, '';
$drain = undef unless length $body;
$content->write($chunk, $drain);
};
$tx->req->content->$drain;
# Process transaction
$tx = $ua->start($tx);
The drain callback passed to "write" in Mojo::Content will be invoked
whenever the entire previous chunk has actually been written.
Non-blocking¶
Mojo::UserAgent has been designed from the ground up to be non-blocking, the
whole blocking API is just a simple convenience wrapper. Especially for high
latency tasks like web crawling this can be extremely useful, because you can
keep many concurrent connections active at the same time.
use Mojo::UserAgent;
use Mojo::IOLoop;
# Concurrent non-blocking requests
my $ua = Mojo::UserAgent->new;
$ua->get('http://metacpan.org/search?q=mojo' => sub {
my ($ua, $mojo) = @_;
...
});
$ua->get('http://metacpan.org/search?q=minion' => sub {
my ($ua, $minion) = @_;
...
});
# Start event loop if necessary
Mojo::IOLoop->start unless Mojo::IOLoop->is_running;
You can take full control of the Mojo::IOLoop event loop.
Concurrent blocking requests¶
You can emulate blocking behavior by using "delay" in Mojo::IOLoop to
synchronize multiple non-blocking requests.
use Mojo::UserAgent;
use Mojo::IOLoop;
# Synchronize non-blocking requests
my $ua = Mojo::UserAgent->new;
my $delay = Mojo::IOLoop->delay(sub {
my ($delay, $mojo, $minion) = @_;
...
});
$ua->get('http://metacpan.org/search?q=mojo' => $delay->begin);
$ua->get('http://metacpan.org/search?q=minion' => $delay->begin);
$delay->wait;
The call to "wait" in Mojo::IOLoop::Delay makes this code portable, it
can now work inside an already running event loop or start one on demand.
WebSockets¶
WebSockets are not just for the server-side, you can use "websocket"
in Mojo::UserAgent to open new connections, which are always non-blocking. The
handshake is a normal HTTP request with a few additional headers, it can even
contain cookies, followed by a 101 response from the server notifying our user
agent that the connection has been established and it can start using the
bi-directional WebSocket protocol.
use Mojo::UserAgent;
use Mojo::IOLoop;
# Open WebSocket to echo service
my $ua = Mojo::UserAgent->new;
$ua->websocket('ws://echo.websocket.org' => sub {
my ($ua, $tx) = @_;
# Check if WebSocket handshake was successful
say 'WebSocket handshake failed!' and return unless $tx->is_websocket;
# Wait for WebSocket to be closed
$tx->on(finish => sub {
my ($tx, $code, $reason) = @_;
say "WebSocket closed with status $code.";
});
# Close WebSocket after receiving one message
$tx->on(message => sub {
my ($tx, $msg) = @_;
say "WebSocket message: $msg";
$tx->finish;
});
# Send a message to the server
$tx->send('Hi!');
});
# Start event loop if necessary
Mojo::IOLoop->start unless Mojo::IOLoop->is_running;
Command line¶
Don't you hate checking huge HTML files from the command line? Thanks to the
command Mojolicious::Command::get that is about to change. You can just pick
the parts that actually matter with the CSS selectors from Mojo::DOM and JSON
Pointers from Mojo::JSON::Pointer.
$ mojo get http://mojolicio.us 'head > title'
How about a list of all id attributes?
$ mojo get http://mojolicio.us '*' attr id
Or the text content of all heading tags?
$ mojo get http://mojolicio.us 'h1, h2, h3' text
Maybe just the text of the third heading?
$ mojo get http://mojolicio.us 'h1, h2, h3' 3 text
You can also extract all text from nested child elements.
$ mojo get http://mojolicio.us '#mojobar' all
The request can be customized as well.
$ mojo get -M POST -c 'Hello!' http://mojolicio.us
$ mojo get -H 'X-Bender: Bite my shiny metal ass!' http://google.com
You can follow redirects and view the headers for all messages.
$ mojo get -r -v http://google.com 'head > title'
Extract just the information you really need from JSON data structures.
$ mojo get https://api.metacpan.org/v0/author/SRI /name
This can be an invaluable tool for testing your applications.
$ ./myapp.pl get /welcome 'head > title'
One-liners¶
For quick hacks and especially testing, ojo one-liners are also a great choice.
$ perl -Mojo -E 'say g("mojolicio.us")->dom->html->head->title->text'
APPLICATIONS¶
Fun Mojolicious application hacks for all occasions.
Basic authentication¶
Basic authentication data will be automatically extracted from the
"Authorization" header.
use Mojolicious::Lite;
get '/' => sub {
my $c = shift;
# Check for username "Bender" and password "rocks"
return $c->render(text => 'Hello Bender!')
if $c->req->url->to_abs->userinfo eq 'Bender:rocks';
# Require authentication
$c->res->headers->www_authenticate('Basic');
$c->render(text => 'Authentication required!', status => 401);
};
app->start;
This can be combined with TLS for a secure authentication mechanism.
$ ./myapp.pl daemon -l 'https://*:3000?cert=./server.crt&key=./server.key'
Adding a configuration file¶
Adding a configuration file to your application is as easy as adding a file to
its home directory and loading the plugin Mojolicious::Plugin::Config. The
default name is based on the value of "moniker" in Mojolicious
("myapp"), appended with a ".conf" extension
("myapp.conf").
$ mkdir myapp
$ cd myapp
$ touch myapp.pl
$ chmod 744 myapp.pl
$ echo '{name => "my Mojolicious application"};' > myapp.conf
Configuration files themselves are just Perl scripts that return a hash
reference, all settings are available through the method "config" in
Mojo and the helper "config" in Mojolicious::Plugin::DefaultHelpers
use Mojolicious::Lite;
plugin 'Config';
my $name = app->config('name');
app->log->debug("Welcome to $name.");
get '/' => 'with_config';
app->start;
__DATA__
@@ with_config.html.ep
<!DOCTYPE html>
<html>
<head><title><%= config 'name' %></title></head>
<body>Welcome to <%= config 'name' %></body>
</html>
Alternatively you can also use configuration files in the JSON format with
Mojolicious::Plugin::JSONConfig.
Adding a plugin to your application¶
To organize your code better and to prevent helpers from cluttering your
application, you can use application specific plugins.
$ mkdir -p lib/MyApp/Plugin
$ touch lib/MyApp/Plugin/MyHelpers.pm
They work just like normal plugins and are also subclasses of
Mojolicious::Plugin. Nested helpers with a prefix based on the plugin name are
an easy way to avoid conflicts.
package MyApp::Plugin::MyHelpers;
use Mojo::Base 'Mojolicious::Plugin';
sub register {
my ($self, $app) = @_;
$app->helper('my_helpers.render_with_header' => sub {
my ($c, @args) = @_;
$c->res->headers->header('X-Mojo' => 'I <3 Mojolicious!');
$c->render(@args);
});
}
1;
You can have as many application specific plugins as you like, the only
difference to normal plugins is that you load them using their full class
name.
use Mojolicious::Lite;
use lib 'lib';
plugin 'MyApp::Plugin::MyHelpers';
get '/' => sub {
my $c = shift;
$c->my_helpers->render_with_header(text => 'I X Mojolicious!');
};
app->start;
Of course these plugins can contain more than just helpers, take a look at
"PLUGINS" in Mojolicious::Plugins for a few ideas.
Adding commands to Mojolicious¶
By now you've probably used many of the built-in commands described in
Mojolicious::Commands, but did you know that you can just add new ones and
that they will be picked up automatically by the command line interface?
package Mojolicious::Command::spy;
use Mojo::Base 'Mojolicious::Command';
has description => 'Spy on application.';
has usage => "Usage: APPLICATION spy [TARGET]\n";
sub run {
my ($self, @args) = @_;
# Leak secret passphrases
say for @{$self->app->secrets} if $args[0] eq 'secrets';
# Leak mode
say $self->app->mode if $args[0] eq 'mode';
}
1;
Command line arguments are passed right through and there are many useful
attributes and methods in Mojolicious::Command that you can use or overload.
$ mojo spy secrets
HelloWorld
$ ./myapp.pl spy secrets
secr3t
And to make your commands application specific, just add a custom namespace to
"namespaces" in Mojolicious::Commands.
# Application
package MyApp;
use Mojo::Base 'Mojolicious';
sub startup {
my $self = shift;
# Add another namespace to load commands from
push @{$self->commands->namespaces}, 'MyApp::Command';
}
1;
Some options like "-m" for the operating mode of your application are
shared by all commands automatically.
$ ./myapp.pl spy -m production mode
production
For a full list of shared options see "SYNOPSIS" in
Mojolicious::Commands.
Running code against your application¶
Ever thought about running a quick one-liner against your Mojolicious
application to test something? Thanks to the command
Mojolicious::Command::eval you can do just that, the application object itself
can be accessed via "app".
$ mojo generate lite_app myapp.pl
$ ./myapp.pl eval 'say for @{app->static->paths}'
The "verbose" options will automatically print the return value or
returned data structure to "STDOUT".
$ ./myapp.pl eval -v 'app->static->paths->[0]'
$ ./myapp.pl eval -V 'app->static->paths'
Making your application installable¶
Ever thought about releasing your Mojolicious application to CPAN? It's actually
much easier than you might think.
$ mojo generate app MyApp
$ cd my_app
$ mv public lib/MyApp/
$ mv templates lib/MyApp/
The trick is to move the "public" and "templates"
directories so they can get automatically installed with the modules.
# Application
package MyApp;
use Mojo::Base 'Mojolicious';
use File::Basename 'dirname';
use File::Spec::Functions 'catdir';
# Every CPAN module needs a version
our $VERSION = '1.0';
sub startup {
my $self = shift;
# Switch to installable home directory
$self->home->parse(catdir(dirname(__FILE__), 'MyApp'));
# Switch to installable "public" directory
$self->static->paths->[0] = $self->home->rel_dir('public');
# Switch to installable "templates" directory
$self->renderer->paths->[0] = $self->home->rel_dir('templates');
$self->plugin('PODRenderer');
my $r = $self->routes;
$r->get('/welcome')->to('example#welcome');
}
1;
That's really everything, now you can package your application like any other
CPAN module.
$ ./script/my_app generate makefile
$ perl Makefile.PL
$ make test
$ make manifest
$ make dist
And if you have a PAUSE account (which can be requested at
<
http://pause.perl.org>) even upload it.
$ mojo cpanify -u USER -p PASS MyApp-0.01.tar.gz
Hello World¶
If every byte matters this is the smallest "Hello World" application
you can write with Mojolicious::Lite.
use Mojolicious::Lite;
any {text => 'Hello World!'};
app->start;
It works because all routes without a pattern default to "/" and
automatic rendering kicks in even if no actual code gets executed by the
router. The renderer just picks up the "text" value from the stash
and generates a response.
Hello World one-liners¶
The "Hello World" example above can get even a little bit shorter in
an ojo one-liner.
$ perl -Mojo -E 'a({text => "Hello World!"})->start' daemon
And you can use all the commands from Mojolicious::Commands.
$ perl -Mojo -E 'a({text => "Hello World!"})->start' get -v /
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.
SUPPORT¶
If you have any questions the documentation might not yet answer, don't hesitate
to ask on the mailing-list <
http://groups.google.com/group/mojolicious>
or the official IRC channel "#mojo" on
"irc.perl.org".