NAME¶
Mojolicious::Guides::Rendering - Rendering
OVERVIEW¶
This document explains content generation with the Mojolicious renderer.
CONCEPTS¶
Essentials every Mojolicious developer should know.
Renderer¶
The renderer is a tiny black box turning stash data into actual responses
utilizing multiple template systems and data encoding modules.
{text => 'Hello.'} -> 200 OK, text/html, 'Hello.'
{json => {x => 3}} -> 200 OK, application/json, '{"x":3}'
{text => 'Oops.', status => '410'} -> 410 Gone, text/html, 'Oops.'
Templates can be automatically detected if enough information is provided by the
developer or routes. Template names are expected to follow the
"template.format.handler" scheme, with "template"
defaulting to "controller/action" or the route name,
"format" defaulting to "html" and "handler" to
"ep".
{controller => 'users', action => 'list'} -> 'users/list.html.ep'
{template => 'foo', format => 'txt'} -> 'foo.txt.ep'
{template => 'foo', handler => 'epl'} -> 'foo.html.epl'
The "controller" value gets decamelized using "decamelize"
in Mojo::Util and "-" characters replaced with "/".
{controller => 'My::Users', action => 'add'} -> 'my/users/add.html.ep'
{controller => 'my-users', action => 'show'} -> 'my/users/show.html.ep'
All templates should be in the "templates" directories of the
application, which can be customized with "paths" in
Mojolicious::Renderer, or one of the the "DATA" sections from
"classes" in Mojolicious::Renderer.
__DATA__
@@ time.html.ep
% use Time::Piece;
% my $now = localtime;
<!DOCTYPE html>
<html>
<head><title>Time</title></head>
<body>The time is <%= $now->hms %>.</body>
</html>
@@ hello.txt.ep
...
The renderer can be easily extended to support additional template systems with
plugins, but more about that later.
Embedded Perl¶
Mojolicious includes a minimalistic but very powerful template system out of the
box called Embedded Perl or "ep" for short. It allows the embedding
of Perl code right into actual content using a small set of special tags and
line start characters. For all templates strict, warnings, utf8 and Perl 5.10
features are automatically enabled.
<% Perl code %>
<%= Perl expression, replaced with XML escaped result %>
<%== Perl expression, replaced with result %>
<%# Comment, useful for debugging %>
<%% Replaced with "<%", useful for generating templates %>
% Perl code line, treated as "<% line =%>"
%= Perl expression line, treated as "<%= line %>"
%== Perl expression line, treated as "<%== line %>"
%# Comment line, useful for debugging
%% Replaced with "%", useful for generating templates
Tags and lines work pretty much the same, but depending on context one will
usually look a bit better. Semicolons get automatically appended to all
expressions.
<% my $i = 10; %>
<ul>
<% for my $j (1 .. $i) { %>
<li>
<%= $j %>
</li>
<% } %>
</ul>
% my $i = 10;
<ul>
% for my $j (1 .. $i) {
<li>
%= $j
</li>
% }
</ul>
Aside from differences in whitespace handling, both examples generate similar
Perl code, a naive translation could look like this.
my $output = '';
my $i = 10;
$output .= '<ul>';
for my $j (1 .. $i) {
$output .= '<li>';
$output .= xml_escape scalar $j;
$output .= '</li>';
}
$output .= '</ul>';
return $output;
An additional equal sign can be used to disable escaping of the characters
"<", ">", "&", "'" and
""" in results from Perl expressions, which is the default to
prevent XSS attacks against your application.
<%= 'I X Mojolicious!' %>
<%== '<p>I X Mojolicious!</p>' %>
Only Mojo::ByteStream objects are excluded from automatic escaping.
<%= b('<p>I X Mojolicious!</p>') %>
Whitespace characters around tags can be trimmed by adding an additional equal
sign to the end of a tag.
<% for (1 .. 3) { %>
<%= 'trim all whitespace characters around this expression' =%>
<% } %>
Newline characters can be escaped with a backslash.
This is <%= 1 + 1 %> a\
single line
And a backslash in front of a newline character can be escaped with another
backslash.
This will <%= 1 + 1 %> result\\
in multiple\\
lines
Stash values that don't have invalid characters in their name get automatically
initialized as normal variables in the template, and the controller object as
both $self and $c.
$c->stash(name => 'tester');
Hello <%= $name %> from <%= $c->tx->remote_address %>.
A prefix like "myapp.*" is commonly used for stash values that you
don't want to expose in templates.
$c->stash('myapp.name' => 'tester');
There are also many helper functions available, but more about that later.
<%= dumper {foo => 'bar'} %>
BASICS¶
Most commonly used features every Mojolicious developer should know about.
Automatic rendering¶
The renderer can be manually started by calling the method "render" in
Mojolicious::Controller, but that's usually not necessary, because it will get
automatically called if nothing has been rendered after the router finished
its work. This also means you can have routes pointing only to templates
without actual actions.
$c->render;
There is one big difference though, by calling it manually you can make sure
that templates use the current controller object, and not the default
controller specified with the attribute "controller_class" in
Mojolicious.
$c->render_later;
You can also disable automatic rendering with the method
"render_later" in Mojolicious::Controller, which can be very useful
to delay rendering when a non-blocking operation has to be performed first.
Rendering templates¶
The renderer will always try to detect the right template, but you can also use
the "template" stash value to render a specific one. Everything
before the last slash will be interpreted as the subdirectory path in which to
find the template.
# foo/bar/baz.*.*
$c->render(template => 'foo/bar/baz');
Choosing a specific "format" and "handler" is just as easy.
# foo/bar/baz.txt.epl
$c->render(template => 'foo/bar/baz', format => 'txt', handler => 'epl');
Because rendering a specific template is the most common task it also has a
shortcut.
$c->render('foo/bar/baz');
If you're not sure in advance if a template actually exists, you can also use
the method "render_maybe" in Mojolicious::Controller to try multiple
alternatives.
$c->render_maybe('localized/baz') or $c->render('foo/bar/baz');
Rendering to strings¶
Sometimes you might want to use the rendered result directly instead of
generating a response, for example to send emails, this can be done with
"render_to_string" in Mojolicious::Controller.
my $html = $c->render_to_string('mail');
No encoding will be performed, making it easy to reuse the result in other
templates or to generate binary data.
my $pdf = $c->render_to_string('invoice', format => 'pdf');
$c->render(data => $pdf, format => 'pdf');
All arguments passed will get localized automatically and are only available
during this render operation.
Template variants¶
To make your application look great on many different devices you can also use
the "variant" stash value to choose between different variants of
your templates.
# foo/bar/baz.html+phone.ep
# foo/bar/baz.html.ep
$c->render('foo/bar/baz', variant => 'phone');
This can be done very liberally since it only applies when a template with the
correct name actually exists and falls back to the generic one otherwise.
Rendering inline templates¶
Some renderers such as "ep" allow templates to be passed inline.
$c->render(inline => 'The result is <%= 1 + 1 %>.');
Since auto detection depends on a path you might have to supply a
"handler" too.
$c->render(inline => "<%= shift->param('foo') %>", handler => 'epl');
Rendering text¶
Characters can be rendered to bytes with the "text" stash value, the
given content will be automatically encoded with "encoding" in
Mojolicious::Renderer.
$c->render(text => 'I X Mojolicious!');
Rendering data¶
Bytes can be rendered with the "data" stash value, no encoding will be
performed.
$c->render(data => $bytes);
Rendering JSON¶
The "json" stash value allows you to pass Perl data structures to the
renderer which get directly encoded to JSON with Mojo::JSON.
$c->render(json => {foo => [1, 'test', 3]});
Status code¶
Response status codes can be changed with the "status" stash value.
$c->render(text => 'Oops.', status => 500);
Content type¶
The "Content-Type" header of the response is actually based on the
MIME type mapping of the "format" stash value.
# Content-Type: text/plain
$c->render(text => 'Hello.', format => 'txt');
# Content-Type: image/png
$c->render(data => $bytes, format => 'png');
These mappings can be easily extended or changed with "types" in
Mojolicious.
# Application
package MyApp;
use Mojo::Base 'Mojolicious';
sub startup {
my $self = shift;
# Add new MIME type
$self->types->type(txt => 'text/plain; charset=utf-8');
}
1;
Stash data¶
Any of the native Perl data types can be passed to templates as references
through the "stash" in Mojolicious::Controller.
$c->stash(author => 'Sebastian');
$c->stash(frameworks => [qw(Catalyst Mojolicious)]);
$c->stash(examples => {convos => 'an IRC app'});
%= $author
%= $frameworks->[1]
%= $examples->{convos}
Since everything is just Perl normal control structures just work.
% for my $framework (@$frameworks) {
<%= $framework %> was written by <%= $author %>.
% }
% if (my $description = $examples->{convos}) {
Convos is a <%= $description %>.
% }
For templates that might get rendered in different ways and where you're not
sure if a stash value will actually be set, you can just use the helper
"stash" in Mojolicious::Plugin::DefaultHelpers.
% if (my $examples = stash 'examples') {
Convos is <%= $examples->{convos} %>.
% }
Helpers¶
Helpers are little functions you can use in templates as well as application and
controller code.
# Template
%= dumper [1, 2, 3]
# Application
my $serialized = $app->dumper([1, 2, 3]);
# Controller
my $serialized = $c->dumper([1, 2, 3]);
The helper "dumper" in Mojolicious::Plugin::DefaultHelpers for example
will use Data::Dumper to serialize whatever data structure you pass it, this
can be very useful for debugging. We differentiate between default helpers
which are more general purpose like "dumper" and tag helpers, which
are template specific and mostly used to generate HTML tags.
%= link_to 'http://mojolicio.us' => begin
Mojolicious
% end
In controllers you can also use the method "helpers" in
Mojolicious::Controller to fully qualify helper calls and ensure that they
don't conflict with existing methods you may already have.
my $serialized = $c->helpers->dumper([1, 2, 3]);
A list of all built-in helpers can be found in
Mojolicious::Plugin::DefaultHelpers and Mojolicious::Plugin::TagHelpers.
Content negotiation¶
For resources with different representations and that require truly RESTful
content negotiation you can also use "respond_to" in
Mojolicious::Controller instead of "render" in
Mojolicious::Controller.
# /hello (Accept: application/json) -> "json"
# /hello (Accept: application/xml) -> "xml"
# /hello.json -> "json"
# /hello.xml -> "xml"
# /hello?format=json -> "json"
# /hello?format=xml -> "xml"
$c->respond_to(
json => {json => {hello => 'world'}},
xml => {text => '<hello>world</hello>'}
);
The best possible representation will be automatically selected from the
"Accept" request header, "format" stash value or
"format" "GET"/"POST" parameter and stored in
the "format" stash value. To change MIME type mappings for the
"Accept" request header or the "Content-Type" response
header you can use "types" in Mojolicious.
$c->respond_to(
json => {json => {hello => 'world'}},
html => sub {
$c->content_for(head => '<meta name="author" content="sri">');
$c->render(template => 'hello', message => 'world')
}
);
Callbacks can be used for representations that are too complex to fit into a
single render call.
# /hello (Accept: application/json) -> "json"
# /hello (Accept: text/html) -> "html"
# /hello (Accept: image/png) -> "any"
# /hello.json -> "json"
# /hello.html -> "html"
# /hello.png -> "any"
# /hello?format=json -> "json"
# /hello?format=html -> "html"
# /hello?format=png -> "any"
$c->respond_to(
json => {json => {hello => 'world'}},
html => {template => 'hello', message => 'world'},
any => {text => '', status => 204}
);
And if no viable representation could be found, the "any" fallback
will be used or an empty 204 response rendered automatically.
# /hello -> "html"
# /hello (Accept: text/html) -> "html"
# /hello (Accept: text/xml) -> "xml"
# /hello (Accept: text/plain) -> undef
# /hello.html -> "html"
# /hello.xml -> "xml"
# /hello.txt -> undef
# /hello?format=html -> "html"
# /hello?format=xml -> "xml"
# /hello?format=txt -> undef
if (my $format = $c->accepts('html', 'xml')) {
...
}
For even more advanced negotiation logic you can also use the helper
"accepts" in Mojolicious::Plugin::DefaultHelpers.
Rendering "exception" and "not_found" pages¶
By now you've probably already encountered the built-in 404 (Not Found) and 500
(Server Error) pages, that get rendered automatically when you make a mistake.
Those are fallbacks for when your own exception handling fails, but especially
during development they can also be a great help, you can render them manually
with the helpers "reply->exception" in
Mojolicious::Plugin::DefaultHelpers and "reply->not_found" in
Mojolicious::Plugin::DefaultHelpers.
use Mojolicious::Lite;
use Scalar::Util 'looks_like_number';
get '/divide/:dividend/by/:divisor' => sub {
my $c = shift;
my ($dividend, $divisor) = $c->param(['dividend', 'divisor']);
# 404
return $c->reply->not_found
unless looks_like_number $dividend && looks_like_number $divisor;
# 500
return $c->reply->exception('Division by zero!') if $divisor == 0;
# 200
$c->render(text => $dividend / $divisor);
};
app->start;
You can also change the templates of those pages, since you most likely want to
show your users something more closely related to your application in
production. The renderer will always try to find
"exception.$mode.$format.*" or "not_found.$mode.$format.*"
before falling back to the built-in default templates.
@@ exception.production.html.ep
<!DOCTYPE html>
<html>
<head><title>Server error</title></head>
<body>
<h1>Exception</h1>
<p><%= $exception->message %></p>
<h1>Stash</h1>
<pre><%= dumper $snapshot %></pre>
</body>
</html>
The hook "before_render" in Mojolicious makes even more advanced
customizations possible by allowing you to intercept and modify the arguments
passed to the renderer.
use Mojolicious::Lite;
hook before_render => sub {
my ($c, $args) = @_;
# Make sure we are rendering the exception template
return unless my $template = $args->{template};
return unless $template eq 'exception';
# Switch to JSON rendering if content negotiation allows it
$args->{json} = {exception => $c->stash('exception')}
if $c->accepts('json');
};
get '/' => sub { die "This sho...ALL GLORY TO THE HYPNOTOAD!\n" };
app->start;
Layouts¶
Most of the time when using "ep" templates you will want to wrap your
generated content in an HTML skeleton, thanks to layouts that's absolutely
trivial.
@@ foo/bar.html.ep
% layout 'mylayout';
Hello World!
@@ layouts/mylayout.html.ep
<!DOCTYPE html>
<html>
<head><title>MyApp</title></head>
<body><%= content %></body>
</html>
You just select the right layout template with the helper "layout" in
Mojolicious::Plugin::DefaultHelpers and place the result of the current
template with the helper "content" in
Mojolicious::Plugin::DefaultHelpers. You can also pass along normal stash
values to the "layout" helper.
@@ foo/bar.html.ep
% layout 'mylayout', title => 'Hi there';
Hello World!
@@ layouts/mylayout.html.ep
<!DOCTYPE html>
<html>
<head><title><%= $title %></title></head>
<body><%= content %></body>
</html>
Instead of the "layout" helper you could also just use the
"layout" stash value, or call "render" in
Mojolicious::Controller with the "layout" argument.
$c->render(template => 'mytemplate', layout => 'mylayout');
To set a "layout" stash value application wide you can use
"defaults" in Mojolicious.
# Application
package MyApp;
use Mojo::Base 'Mojolicious';
sub startup {
my $self = shift;
# Default layout
$self->defaults(layout => 'mylayout');
}
1;
Layouts can also be used with "render_to_string" in
Mojolicious::Controller, but the "layout" value needs to be passed
as a render argument (not a stash value).
my $html = $c->render_to_string('reminder', layout => 'mail');
Including partial templates¶
Like most helpers "include" in Mojolicious::Plugin::DefaultHelpers is
just a shortcut to make your life a little easier.
@@ foo/bar.html.ep
<!DOCTYPE html>
<html>
%= include 'header'
<body>Bar</body>
</html>
@@ header.html.ep
<head><title>Howdy</title></head>
Instead of "include" you could also just call
"render_to_string" in Mojolicious::Controller.
@@ foo/bar.html.ep
<!DOCTYPE html>
<html>
%= $c->render_to_string('header')
<body>Bar</body>
</html>
@@ header.html.ep
<head><title>Howdy</title></head>
Reusable template blocks¶
It's never fun to repeat yourself, that's why you can build reusable template
blocks in "ep" that work very similar to normal Perl functions.
@@ welcome.html.ep
<% my $block = begin %>
<% my $name = shift; %>
Hello <%= $name %>.
<% end %>
<%= $block->('Sebastian') %>
<%= $block->('Sara') %>
Blocks are always delimited by the "begin" and "end"
keywords.
@@ welcome.html.ep
% my $block = begin
% my $name = shift;
Hello <%= $name %>.
% end
% for (1 .. 10) {
%== $block->('Sebastian')
% }
A naive translation to Perl code could look like this.
@@ welcome.html.pl
my $output = '';
my $block = sub {
my $name = shift;
my $output = '';
$output .= 'Hello ';
$output .= xml_escape scalar $name;
$output .= '.';
return Mojo::ByteStream->new($output);
}
for (1 .. 10) {
$output .= scalar $block->('Sebastian');
}
return $output;
Adding helpers¶
You should always try to keep your actions small and reuse as much code as
possible. Helpers make this very easy, you can use them to do pretty much
anything an action could do.
use Mojolicious::Lite;
helper debug => sub {
my ($c, $str) = @_;
$c->app->log->debug($str);
};
get '/' => sub {
my $c = shift;
$c->debug('Hello from an action!');
} => 'index';
app->start;
__DATA__
@@ index.html.ep
% debug 'Hello from a template!';
Helpers can also accept template blocks as last argument, this for example
allows very pleasant to use tag helpers and filters. Wrapping the helper
result into a Mojo::ByteStream object can prevent accidental double escaping.
use Mojolicious::Lite;
use Mojo::ByteStream;
helper trim_newline => sub {
my ($c, $block) = @_;
my $result = $block->();
$result =~ s/\n//g;
return Mojo::ByteStream->new($result);
};
get '/' => 'index';
app->start;
__DATA__
@@ index.html.ep
%= trim_newline begin
Some text.
%= 1 + 1
More text.
% end
Similar to stash values you can use a prefix like "myapp.*" to keep
helpers from getting exposed in templates and to organize them into namespaces
as your application grows. Every prefix automatically becomes a helper that
returns a proxy object containing the current controller object and on which
you can call the nested helpers.
use Mojolicious::Lite;
helper 'cache_control.no_caching' => sub {
my $c = shift;
$c->res->headers->cache_control('private, max-age=0, no-cache');
};
helper 'cache_control.five_minutes' => sub {
my $c = shift;
$c->res->headers->cache_control('public, max-age=300');
};
get '/news' => sub {
my $c = shift;
$c->cache_control->no_caching;
$c->render(text => 'Always up to date.');
};
get '/some_older_story' => sub {
my $c = shift;
$c->cache_control->five_minutes;
$c->render(text => 'This one can be cached for a bit.');
};
app->start;
While helpers can also be redefined, this should only be done very carefully to
avoid conflicts.
Content blocks¶
Blocks and the helper "content_for" in
Mojolicious::Plugin::DefaultHelpers can also be used to pass whole sections of
the template to the layout.
@@ foo/bar.html.ep
% layout 'mylayout';
% content_for header => begin
<meta http-equiv="Content-Type" content="text/html">
% end
<div>Hello World!</div>
% content_for header => begin
<meta http-equiv="Pragma" content="no-cache">
% end
@@ layouts/mylayout.html.ep
<!DOCTYPE html>
<html>
<head><%= content_for 'header' %></head>
<body><%= content %></body>
</html>
Template inheritance¶
Inheritance takes the layout concept above one step further, the helpers
"content" in Mojolicious::Plugin::DefaultHelpers and
"extends" in Mojolicious::Plugin::DefaultHelpers allow you to build
a skeleton template with named blocks that child templates can override.
@@ first.html.ep
<!DOCTYPE html>
<html>
<head><title>Hello</title></head>
<body>
%= content header => begin
Default header
% end
<div>Hello World!</div>
%= content footer => begin
Default footer
% end
</body>
</html>
@@ second.html.ep
% extends 'first';
% content header => begin
New header
% end
@@ third.html.ep
% extends 'second';
% content footer => begin
New footer
% end
This chain could go on and on to allow a very high level of template reuse.
You can use "validation" in Mojolicious::Controller to validate
"GET" and "POST" parameters submitted to your application.
All unknown fields will be ignored by default, so you have to decide which
should be required or optional before you can perform checks on their values.
Every check is performed right away, so you can use the results immediately to
build more advanced validation logic with methods like "is_valid" in
Mojolicious::Validator::Validation.
use Mojolicious::Lite;
get '/' => sub {
my $c = shift;
# Check if parameters have been submitted
my $validation = $c->validation;
return $c->render unless $validation->has_data;
# Validate parameters ("pass_again" depends on "pass")
$validation->required('user')->size(1, 20)->like(qr/^[e-t]+$/);
$validation->required('pass_again')->equal_to('pass')
if $validation->optional('pass')->size(7, 500)->is_valid;
# Render confirmation if validation was successful
$c->render('thanks') unless $validation->has_error;
} => 'index';
app->start;
__DATA__
@@ index.html.ep
<!DOCTYPE html>
<html>
<head>
<style>
label.field-with-error { color: #dd7e5e }
input.field-with-error { background-color: #fd9e7e }
</style>
</head>
<body>
%= form_for index => begin
%= label_for user => 'Username (required, 1-20 characters, only e-t)'
<br>
%= text_field 'user'
%= submit_button
<br>
%= label_for pass => 'Password (optional, 7-500 characters)'
<br>
%= password_field 'pass'
<br>
%= label_for pass_again => 'Password again (equal to the value above)'
<br>
%= password_field 'pass_again'
% end
</body>
</html>
@@ thanks.html.ep
<!DOCTYPE html>
<html><body>Thank you <%= validation->param('user') %>.</body></html>
Form elements generated with tag helpers from Mojolicious::Plugin::TagHelpers
will automatically remember their previous values and add the class
"field-with-error" for fields that failed validation to make styling
with CSS easier.
<label class="field-with-error" for="user">
Username (required, only characters e-t)
</label>
<input class="field-with-error" type="text" name="user" value="sri" />
For a full list of available checks see also "CHECKS" in
Mojolicious::Validator.
Validation checks can be registered with "add_check" in
Mojolicious::Validator and return a false value if they were successful. A
true value may be used to pass along additional information which can then be
retrieved with "error" in Mojolicious::Validator::Validation.
use Mojolicious::Lite;
# Add "range" check
app->validator->add_check(range => sub {
my ($validation, $name, $value, $min, $max) = @_;
return $value < $min || $value > $max;
});
get '/' => 'form';
post '/test' => sub {
my $c = shift;
# Validate parameters with custom check
my $validation = $c->validation;
$validation->required('number')->range(3, 23);
# Render form again if validation failed
return $c->render('form') if $validation->has_error;
# Prevent double submit with redirect
$c->flash(number => $validation->param('number'));
$c->redirect_to('form');
};
app->start;
__DATA__
@@ form.html.ep
<!DOCTYPE html>
<html>
<body>
% if (my $number = flash 'number') {
<p>Thanks, the number <%= $number %> was valid.</p>
% }
%= form_for test => begin
% if (my $err = validation->error('number')) {
<p>
%= 'Value is required.' if $err->[0] eq 'required'
%= 'Value needs to be between 3 and 23.' if $err->[0] eq 'range'
</p>
% }
%= text_field 'number'
%= submit_button
% end
</body>
</html>
The methods "flash" in Mojolicious::Controller and
"redirect_to" in Mojolicious::Controller are often used together to
prevent double form submission.
Cross-site request forgery¶
CSRF is a very common attack on web applications that trick your logged in users
to submit forms they did not intend to send. All you have to do to protect
your users from this, is to add an additional hidden field to your forms with
"csrf_field" in Mojolicious::Plugin::TagHelpers and validate it with
"csrf_protect" in Mojolicious::Validator::Validation.
use Mojolicious::Lite;
get '/' => {template => 'target'};
post '/' => sub {
my $c = shift;
# Check CSRF token
my $validation = $c->validation;
return $c->render(text => 'Bad CSRF token!', status => 403)
if $validation->csrf_protect->has_error('csrf_token');
my $city = $validation->required('city')->param('city');
$c->render(text => "Low orbit ion cannon pointed at $city!")
unless $validation->has_error;
} => 'target';
app->start;
__DATA__
@@ target.html.ep
<!DOCTYPE html>
<html>
<body>
%= form_for target => begin
%= csrf_field
%= label_for city => 'Which city to point low orbit ion cannon at?'
%= text_field 'city'
%= submit_button
%= end
</body>
</html>
The token can also be submitted with the "X-CSRF-Token" request
header.
ADVANCED¶
Less commonly used and more powerful features.
Serving static files¶
Static files are automatically served from your "DATA" sections and
"public" directories, and if that's not enough you can also serve
them manually with "reply->static" in
Mojolicious::Plugin::DefaultHelpers.
use Mojolicious::Lite;
get '/some_static_file' => sub {
my $c = shift;
$c->res->headers->content_disposition('attachment; filename=bar.png;');
$c->reply->static('foo/bar.png');
};
app->start;
Custom responses¶
Most response content, static as well as dynamic, gets served through
Mojo::Asset::File and Mojo::Asset::Memory objects. For somewhat static
content, like cached JSON data or temporary file, you can create your own and
use the helper "reply->asset" in
Mojolicious::Plugin::DefaultHelpers to serve them while allowing content
negotiation to be performed with "Range",
"If-Modified-Since" and "If-None-Match" headers.
use Mojolicious::Lite;
get '/leak' => sub {
my $c = shift;
$c->res->headers->content_type('text/plain');
$c->reply->asset(Mojo::Asset::File->new(path => '/etc/passwd'));
};
app->start;
For even more control you can also just skip the helper and use
"rendered" in Mojolicious::Controller to tell the renderer when
you're done generating a response.
use Mojolicious::Lite;
get '/leak' => sub {
my $c = shift;
$c->res->headers->content_type('text/plain');
$c->res->content->asset(Mojo::Asset::File->new(path => '/etc/passwd'));
$c->rendered(200);
};
app->start;
Helper plugins¶
Some helpers might be useful enough for you to share them between multiple
applications, plugins make that very simple.
package Mojolicious::Plugin::DebugHelper;
use Mojo::Base 'Mojolicious::Plugin';
sub register {
my ($self, $app) = @_;
$app->helper(debug => sub {
my ($c, $str) = @_;
$c->app->log->debug($str);
});
}
1;
The "register" method will be called when you load the plugin and to
add your helper to the application you can use "helper" in
Mojolicious.
use Mojolicious::Lite;
plugin 'DebugHelper';
get '/' => sub {
my $c = shift;
$c->debug('It works.');
$c->render(text => 'Hello.');
};
app->start;
A skeleton for a full CPAN compatible plugin distribution can be automatically
generated.
$ mojo generate plugin DebugHelper
And if you have a "PAUSE" account (which can be requested at
<
http://pause.perl.org>), you are only a few commands away from
releasing it to CPAN.
$ perl Makefile.PL
$ make test
$ make manifest
$ make dist
$ mojo cpanify -u USER -p PASS Mojolicious-Plugin-DebugHelper-0.01.tar.gz
Bundling assets with plugins¶
Assets such as templates and static files can be easily bundled with your
plugins, even if you plan to release them to CPAN.
$ mojo generate plugin AlertAssets
$ mkdir Mojolicious-Plugin-AlertAssets/lib/Mojolicious/Plugin/AlertAssets
$ cd Mojolicious-Plugin-AlertAssets/lib/Mojolicious/Plugin/AlertAssets
$ mkdir public
$ echo 'alert("Hello World!");' > public/alertassets.js
$ mkdir templates
$ echo '%= javascript "/alertassets.js"' > templates/alertassets.html.ep
Just append their respective directories to the list of search paths when
"register" is called.
package Mojolicious::Plugin::AlertAssets;
use Mojo::Base 'Mojolicious::Plugin';
use File::Basename 'dirname';
use File::Spec::Functions 'catdir';
sub register {
my ($self, $app) = @_;
# Append "templates" and "public" directories
my $base = catdir(dirname(__FILE__), 'AlertAssets');
push @{$app->renderer->paths}, catdir($base, 'templates');
push @{$app->static->paths}, catdir($base, 'public');
}
1;
Both will work just like normal "templates" and "public"
directories once you've installed and loaded the plugin, with slightly lower
precedence.
use Mojolicious::Lite;
plugin 'AlertAssets';
get '/alert_me';
app->start;
__DATA__
@@ alert_me.html.ep
<!DOCTYPE html>
<html>
<head>
<title>Alert me!</title>
%= include 'alertassets'
</head>
<body>You've been alerted.</body>
</html>
And it works just the same for assets bundled in the "DATA" section of
your plugin.
package Mojolicious::Plugin::AlertAssets;
use Mojo::Base 'Mojolicious::Plugin';
sub register {
my ($self, $app) = @_;
# Append class
push @{$app->renderer->classes}, __PACKAGE__;
push @{$app->static->classes}, __PACKAGE__;
}
1;
__DATA__
@@ alertassets.js
alert("Hello World!");
@@ alertassets.html.ep
%= javascript "/alertassets.js"
Post-processing dynamic content¶
While post-processing tasks are generally very easy with the hook
"after_dispatch" in Mojolicious, for content generated by the
renderer it is a lot more efficient to use "after_render" in
Mojolicious.
use Mojolicious::Lite;
use IO::Compress::Gzip 'gzip';
hook after_render => sub {
my ($c, $output, $format) = @_;
# Check if "gzip => 1" has been set in the stash
return unless $c->stash->{gzip};
# Check if user agent accepts gzip compression
return unless ($c->req->headers->accept_encoding // '') =~ /gzip/i;
$c->res->headers->append(Vary => 'Accept-Encoding');
# Compress content with gzip
$c->res->headers->content_encoding('gzip');
gzip $output, \my $compressed;
$$output = $compressed;
};
get '/' => {template => 'hello', title => 'Hello', gzip => 1};
app->start;
__DATA__
@@ hello.html.ep
<!DOCTYPE html>
<html>
<head><title><%= title %></title></head>
<body>Compressed content.</body>
</html>
Chunked transfer encoding¶
For very dynamic content you might not know the response content length in
advance, that's where the "chunked" transfer encoding and
"write_chunk" in Mojolicious::Controller come in handy. A common use
would be to send the "head" section of an HTML document to the
browser in advance and speed up preloading of referenced images and
stylesheets.
use Mojolicious::Lite;
get '/' => sub {
my $c = shift;
$c->write_chunk('<html><head><title>Example</title></head>' => sub {
my $c = shift;
$c->finish('<body>Example</body></html>');
});
};
app->start;
The optional drain callback ensures that all previous chunks have been written
before processing continues. An empty chunk or call to "finish" in
Mojolicious::Controller marks the end of the stream.
HTTP/1.1 200 OK
Connection: keep-alive
Date: Sat, 13 Sep 2014 16:48:29 GMT
Transfer-Encoding: chunked
Server: Mojolicious (Perl)
29
<html><head><title>Example</title></head>
1b
<body>Example</body></html>
0
Especially in combination with long inactivity timeouts this can be very useful
for Comet (long polling). Due to limitations in some web servers this might
not work perfectly in all deployment environments.
Encoding¶
Templates stored in files are expected to be "UTF-8" by default, but
that can be easily changed with "encoding" in Mojolicious::Renderer.
# Application
package MyApp;
use Mojo::Base 'Mojolicious';
sub startup {
my $self = shift;
# Different encoding
$self->renderer->encoding('koi8-r');
}
1;
All templates from the "DATA" section are bound to the encoding of the
Perl script.
use Mojolicious::Lite;
get '/heart';
app->start;
__DATA__
@@ heart.html.ep
I X Mojolicious!
Base64 encoded DATA files¶
Base64 encoded static files such as images can be easily stored in the
"DATA" section of your application, similar to templates.
@@ favicon.ico (base64)
...base64 encoded image...
Inflating DATA templates¶
Templates stored in files get preferred over files from the "DATA"
section, this allows you to include a default set of templates in your
application that the user can later customize. The command
Mojolicious::Command::inflate will write all templates and static files from
the "DATA" section into actual files in the "templates"
and "public" directories.
$ ./myapp.pl inflate
Customizing the template syntax¶
You can easily change the whole template syntax by loading
Mojolicious::Plugin::EPRenderer with a custom configuration.
use Mojolicious::Lite;
plugin EPRenderer => {
name => 'mustache',
template => {
tag_start => '{{',
tag_end => '}}'
}
};
get '/:name' => {name => 'Anonymous'} => 'index';
app->start;
__DATA__
@@ index.html.mustache
Hello {{= $name }}.
Mojo::Template contains the whole list of available options.
Adding your favorite template system¶
Maybe you would prefer a different template system than "ep", and
there is not already a plugin on CPAN for your favorite one, all you have to
do is add a new "handler" with "add_handler" in
Mojolicious::Renderer when "register" is called.
package Mojolicious::Plugin::MyRenderer;
use Mojo::Base 'Mojolicious::Plugin';
sub register {
my ($self, $app) = @_;
# Add "mine" handler
$app->renderer->add_handler(mine => sub {
my ($renderer, $c, $output, $options) = @_;
# Check for one-time use inline template
my $inline = $options->{inline};
# Check for absolute template path
my $path = $renderer->template_path($options);
# Check for appropriate template in DATA section
my $data = $renderer->get_data_template($options);
# This part is up to you and your template system :)
...
# Just die if an error occurs
die 'Something went wrong with the template';
# Or pass the rendered result back to the renderer
$$output = 'Hello World!';
# And return true if something has been rendered or false otherwise
return 1;
});
}
1;
Since most template systems don't support templates in the "DATA"
section, the renderer provides methods to help you with that.
use Mojolicious::Lite;
plugin 'MyRenderer';
get '/' => 'index';
app->start;
__DATA__
@@ index.html.mine
...
Adding a handler to generate binary data¶
By default the renderer assumes that every "handler" generates
characters that need to be automatically encoded, but this can be easily
disabled if you're generating bytes instead.
use Mojolicious::Lite;
use Storable 'nfreeze';
# Add "storable" handler
app->renderer->add_handler(storable => sub {
my ($renderer, $c, $output, $options) = @_;
# Disable automatic encoding
delete $options->{encoding};
# Encode data from stash value
$$output = nfreeze delete $c->stash->{storable};
return 1;
});
get '/' => {storable => {i => 'X mojolicious'}, handler => 'storable'};
app->start;
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".