Provided by: libmojolicious-perl_4.63+dfsg-1_all 
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 has many configuration options and is known to work on every platform Perl works on.
$ ./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://127.0.0.1:3000.
On UNIX platforms you can also add preforking with Mojo::Server::Prefork.
$ ./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.
$ ./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 Mojo::IOLoop timers.
use Mojolicious::Lite;
Mojo::IOLoop->timer(0 => 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 that will allow you to take advantage of multiple CPU cores and copy-on-write.
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.
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-HTTPS" 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 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-HTTPS 0;
}
}
Apache/mod_proxy
Another good reverse proxy is Apache 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-HTTPS "0"
</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.
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
HTTP::Server::PSGI: Accepting connections at http://0:5000/
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
If an older server adapter is not be able to correctly detect the application home directory, you can
simply use the MOJO_HOME environment variable.
$ MOJO_HOME=/home/sri/myapp plackup ./script/myapp
HTTP::Server::PSGI: Accepting connections at http://0:5000/
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 'myapp.pl';
};
But you could even use middleware right in your application.
use Mojolicious::Lite;
use Plack::Builder;
get '/welcome' => sub {
my $self = shift;
$self->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-Protocol" header is set to "https"
app->hook(before_dispatch => sub {
my $c = shift;
$c->req->url->base->scheme('https')
if $c->req->headers->header('X-Forwarded-Protocol') eq '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'});
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 clients.
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 $self = shift;
$self->ua->get('api.metacpan.org/v0/module/_search?q=mojolicious' => sub {
my ($ua, $tx) = @_;
$self->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 parallel requests can be easily synchronized with "delay" in Mojo::IOLoop.
use Mojolicious::Lite;
use Mojo::IOLoop;
use Mojo::URL;
# Search MetaCPAN for "mojo" and "mango"
get '/' => sub {
my $self = shift;
# Prepare response in two steps
Mojo::IOLoop->delay(
# Parallel requests
sub {
my $delay = shift;
my $url = Mojo::URL->new('api.metacpan.org/v0/module/_search');
$url->query({sort => 'date:desc'});
$self->ua->get($url->clone->query({q => 'mojo'}) => $delay->begin);
$self->ua->get($url->clone->query({q => 'mango'}) => $delay->begin);
},
# Delayed rendering
sub {
my ($delay, $mojo, $mango) = @_;
$self->render(json => {
mojo => $mojo->res->json('/hits/hits/0/_source/release'),
mango => $mango->res->json('/hits/hits/0/_source/release')
});
}
);
};
app->start;
Timers
Another primary feature of the Mojo::IOLoop event loop are timers, which can for example be used to delay
rendering of a response, and unlike "sleep", won't block any other requests that might be processed in
parallel.
use Mojolicious::Lite;
use Mojo::IOLoop;
# Wait 3 seconds before rendering a response
get '/' => sub {
my $self = shift;
Mojo::IOLoop->timer(3 => sub {
$self->render(text => 'Delayed by 3 seconds!');
});
};
app->start;
Recurring timers 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 $self = shift;
# Start recurring timer
my $i = 1;
my $id = Mojo::IOLoop->recurring(1 => sub {
$self->write_chunk($i);
$self->finish if $i++ == 5;
});
# Stop recurring timer
$self->on(finish => sub { Mojo::IOLoop->remove($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;
# Count seconds since startup
my $i = 0;
Mojo::IOLoop->recurring(1 => sub { $i++ });
# Show counter
get '/' => sub {
my $self = shift;
$self->render(text => "About $i seconds running!");
};
app->start;
Since timers and other low level event watchers are also independent from applications, errors can't get
logged automatically, you can change that by subscribing to the event "error" in Mojo::Reactor.
# Forward error messages to the application log
Mojo::IOLoop->singleton->reactor->on(error => sub {
my ($reactor, $err) = @_;
app->log->error($err);
});
Just remember that all events are processed cooperatively, so your callbacks shouldn't block for too
long.
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;
use Mojo::IOLoop;
# Template with browser-side code
get '/' => 'index';
# WebSocket echo service
websocket '/echo' => sub {
my $self = shift;
# Opened
$self->app->log->debug('WebSocket opened.');
# Increase inactivity timeout for connection a bit
Mojo::IOLoop->stream($self->tx->connection)->timeout(300);
# Incoming message
$self->on(message => sub {
my ($self, $msg) = @_;
$self->send("echo: $msg");
});
# Closed
$self->on(finish => sub {
my ($self, $code, $reason) = @_;
$self->app->log->debug("WebSocket closed with status $code.");
});
};
app->start;
__DATA__
@@ index.html.ep
<!DOCTYPE html>
<html>
<head><title>Echo</title></head>
<body>
<script>
var ws = new WebSocket('<%= url_for('echo')->to_abs %>');
// Incoming messages
ws.onmessage = function(event) {
document.body.innerHTML += event.data + '<br/>';
};
// Outgoing messages
window.setInterval(function() {
ws.send('Hello Mojo!');
}, 1000);
</script>
</body>
</html>
The event "finish" in Mojo::Transaction::WebSocket will be emitted right after the WebSocket connection
has been closed.
Testing WebSocket web services
While the message flow on WebSocket connections can be rather dynamic, it more often than not is quite
predictable, which allows this rather pleasant Test::Mojo API to be used.
use Test::More;
use Test::Mojo;
# Include application
use FindBin;
require "$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;
use Mojo::IOLoop;
# Template with browser-side code
get '/' => 'index';
# EventSource for log messages
get '/events' => sub {
my $self = shift;
# Increase inactivity timeout for connection a bit
Mojo::IOLoop->stream($self->tx->connection)->timeout(300);
# Change content type
$self->res->headers->content_type('text/event-stream');
# Subscribe to "message" event and forward "log" events to browser
my $cb = $self->app->log->on(message => sub {
my ($log, $level, @lines) = @_;
$self->write("event:log\ndata: [$level] @lines\n\n");
});
# Unsubscribe from "message" event again once we are done
$self->on(finish => sub {
my $self = shift;
$self->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';
# Emit "request" event early for requests that get upgraded to multipart
hook after_build_tx => sub {
my $tx = shift;
weaken $tx;
$tx->req->content->on(upgrade => sub { $tx->emit('request') });
};
# Upload form in DATA section
get '/' => 'index';
# Streaming multipart upload (invoked twice, due to early "request" event)
post '/upload' => sub {
my $self = shift;
# First invocation, subscribe to "part" event to find the right one
return $self->req->content->on(part => sub {
my ($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
$self->app->log->debug(length($bytes) . ' bytes uploaded.');
});
});
}) unless $self->req->is_finished;
# Second invocation, render response
$self->render(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 $self = shift;
my $w;
$w = AE::timer 3, 0, sub {
$self->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.
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 unit 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 elements recursively to extract more than just text
for my $e ($tx->res->dom('*')->each) {
# Text before this element
print $e->text_before(0);
# Also include alternate text for images
print $e->{alt} if $e->type eq 'img';
# Text for elements without children
print $e->text(0) unless $e->children->size;
# Text after last element
print $e->text_after(0) unless $e->next;
}
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.
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/mango.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('latest.mojolicio.us');
$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 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
$ua->start($tx);
The event "read" in Mojo::Content will be emitted for every chunk of data that is received, even
"chunked" encoding 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
$ua->start($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 parallel connections active at the same time.
use Mojo::UserAgent;
use Mojo::IOLoop;
# Parallel non-blocking requests
my $ua = Mojo::UserAgent->new;
$ua->get('http://metacpan.org/search?q=mojo' => sub {
my ($ua, $mojo) = @_;
...
});
$ua->get('http://metacpan.org/search?q=mango' => sub {
my ($ua, $mango) = @_;
...
});
# Start event loop if necessary
Mojo::IOLoop->start unless Mojo::IOLoop->is_running;
You can take full control of the Mojo::IOLoop event loop.
Parallel 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 and capture results
my $ua = Mojo::UserAgent->new;
my $delay = Mojo::IOLoop->delay;
$ua->get('http://metacpan.org/search?q=mojo' => $delay->begin);
$ua->get('http://metacpan.org/search?q=mango' => $delay->begin);
my ($mojo, $mango) = $delay->wait;
The event "finish" in Mojo::IOLoop::Delay can be used for code that needs to be able to work standalone
as well as inside an already running event loop.
use Mojo::UserAgent;
use Mojo::IOLoop;
# Synchronize non-blocking requests portably
my $ua = Mojo::UserAgent->new;
my $delay = Mojo::IOLoop->delay;
$delay->on(finish => sub {
my ($delay, $mojo, $mango) = @_;
...
});
$ua->get('http://metacpan.org/search?q=mojo' => $delay->begin);
$ua->get('http://metacpan.org/search?q=mango' => $delay->begin);
$delay->wait unless Mojo::IOLoop->is_running;
Command line
Don't you hate checking huge HTML files from the command line? Thanks to the "mojo get" command 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'
HACKS
Fun hacks you might not use very often but that might come in handy some day.
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.\n";
has usage => "usage: $0 spy [TARGET]\n";
sub run {
my ($self, $target) = @_;
# Leak secret passphrases
say for @{$self->app->secrets} if $target eq 'secrets';
}
1;
There are many more 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 put them in a different namespace.
# 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;
Running code against your application
Ever thought about running a quick one-liner against your Mojolicious application to test something?
Thanks to the "eval" command 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".
perl v5.18.1 2013-12-19 Mojolicious::Guides::Cookbook(3pm)