SYNOPSIS
#!/usr/bin/perl
use Dancer;
get '/hello/:name' => sub {
return "Why, hello there " . param('name');
};
dance;
The above is a basic but functional web app created with Dancer. If you
want to see more examples and get up and running quickly, check out the
Dancer::Introduction and the Dancer::Cookbook. For examples on
deploying your Dancer applications, see Dancer::Deployment.
DESCRIPTION
Dancer is a web application framework designed to be as effortless as
possible for the developer, taking care of the boring bits as easily as
possible, yet staying out of your way and letting you get on with
writing your code.
Dancer aims to provide the simplest way for writing web applications,
and offers the flexibility to scale between a very simple lightweight
web service consisting of a few lines of code in a single file, all the
way up to a more complex fully-fledged web application with session
support, templates for views and layouts, etc.
If you don't want to write CGI scripts by hand, and find Catalyst too
big or cumbersome for your project, Dancer is what you need.
Dancer has few pre-requisites, so your Dancer webapps will be easy to
deploy.
Dancer apps can be used with an embedded web server (great for easy
testing), and can run under PSGI/Plack for easy deployment in a variety
of webserver environments.
MORE DOCUMENTATION
This documentation describes all the exported symbols of Dancer. If you
want a quick start guide to discover the framework, you should look at
Dancer::Introduction, or Dancer::Tutorial to learn by example.
If you want to have specific examples of code for real-life problems,
see the Dancer::Cookbook.
If you want to see configuration examples of different deployment
solutions involving Dancer and Plack, see Dancer::Deployment.
You can find out more about the many useful plugins available for
Dancer in Dancer::Plugins.
EXPORTS
By default, use Dancer exports all the functions below plus sets up
your app. You can control the exporting through the normal Exporter
mechanism. For example:
# Just export the route controllers
use Dancer qw(get post put patch del);
# Export everything but pass to avoid clashing with Test::More
use Test::More;
use Dancer qw(!pass);
Please note that the utf8 and strict pragmas are exported by this
module.
By default, the warnings pragma will also be exported, meaning your
app/script will be running under use warnings. If you do not want this,
set the global_warnings setting to a false value.
There are also some special tags to control exports and behaviour.
:moose
This will export everything except functions which clash with Moose.
Currently these are after and before.
:syntax
This tells Dancer to just export symbols and not set up your app. This
is most useful for writing Dancer code outside of your main route
handler.
:tests
This will export everything except functions which clash with commonly
used testing modules. Currently these are pass.
It can be combined with other export pragmas. For example, while
testing...
use Test::More;
use Dancer qw(:syntax :tests);
# Test::Most also exports "set" and "any"
use Test::Most;
use Dancer qw(:syntax :tests !set !any);
# Alternatively, if you want to use Dancer's set and any...
use Test::Most qw(!set !any);
use Dancer qw(:syntax :tests);
:script
This will export all the keywords, load the configuration, and will not
try to parse command-line arguments via Dancer::GetOpt.
This is useful when you want to use your Dancer application from a
script.
use MyApp;
use Dancer ':script';
MyApp::schema('DBSchema')->deploy();
Note that using :script will disable command-line parsing for all
subsequent invocations of use Dancer (such that you don't have to use
:script for each and every module to make sure the command-line
arguments don't get stolen by Dancer).
!keyword
If you want to simply prevent Dancer from exporting specific keywords
(perhaps you plan to implement them yourself in a different way, or you
don't plan to use them and they clash with another module you're
loading), you can simply exclude them:
use Dancer qw(!session);
The above would import all keywords as normal, with the exception of
session.
FUNCTIONS
after
Deprecated - see the after hook.
any
Defines a route for multiple HTTP methods at once:
any ['get', 'post'] => '/myaction' => sub {
# code
};
Or even, a route handler that would match any HTTP methods:
any '/myaction' => sub {
# code
};
before
Deprecated - see the before hook.
before_template
Deprecated - see the before_template hook.
cookies
Accesses cookies values, it returns a HashRef of Dancer::Cookie
objects:
get '/some_action' => sub {
my $cookie = cookies->{name};
return $cookie->value;
};
In the case you have stored something other than a Scalar in your
cookie:
get '/some_action' => sub {
my $cookie = cookies->{oauth};
my %values = $cookie->value;
return ($values{token}, $values{token_secret});
};
cookie
Accesses a cookie value (or sets it). Note that this method will
eventually be preferred over set_cookie.
cookie lang => "fr-FR"; # set a cookie and return its value
cookie lang => "fr-FR", expires => "2 hours"; # extra cookie info
cookie "lang" # return a cookie value
If your cookie value is a key/value URI string, like
token=ABC&user=foo
cookie will only return the first part (token=ABC) if called in scalar
context. Use list context to fetch them all:
my @values = cookie "name";
Note that if the client has sent more than one cookie with the same
value, the one returned will be the last one seen. This should only
happen if you have set multiple cookies with the same name but
different paths. So, don't do that.
config
Accesses the configuration of the application:
get '/appname' => sub {
return "This is " . config->{appname};
};
content_type
Sets the content-type rendered, for the current route handler:
get '/cat/:txtfile' => sub {
content_type 'text/plain';
# here we can dump the contents of param('txtfile')
};
You can use abbreviations for content types. For instance:
get '/svg/:id' => sub {
content_type 'svg';
# here we can dump the image with id param('id')
};
Note that if you want to change the default content-type for every
route, you have to change the content_type setting instead.
dance
Alias for the start keyword.
dancer_version
Returns the version of Dancer. If you need the major version, do
something like:
int(dancer_version);
debug
Logs a message of debug level:
debug "This is a debug message";
See Dancer::Logger for details on how to configure where log messages
go.
dirname
Returns the dirname of the path given:
my $dir = dirname($some_path);
engine
Given a namespace, returns the current engine object
my $template_engine = engine 'template';
my $html = $template_engine->apply_renderer(...);
$template_engine->apply_layout($html);
error
Logs a message of error level:
error "This is an error message";
See Dancer::Logger for details on how to configure where log messages
go.
false
Constant that returns a false value (0).
forward
Runs an internal redirect of the current request to another request.
This helps you avoid having to redirect the user using HTTP and set
another request to your application.
It effectively lets you chain routes together in a clean manner.
get '/demo/articles/:article_id' => sub {
# you'll have to implement this next sub yourself :)
change_the_main_database_to_demo();
forward "/articles/" . params->{article_id};
};
In the above example, the users that reach /demo/articles/30 will
actually reach /articles/30 but we've changed the database to demo
before.
This is pretty cool because it lets us retain our paths and offer a
demo database by merely going to /demo/....
You'll notice that in the example we didn't indicate whether it was GET
or POST. That is because forward chains the same type of route the user
reached. If it was a GET, it will remain a GET (but if you do need to
change the method, you can do so; read on below for details.)
WARNING : using forward will not preserve session data set on the
forwarding rule.
WARNING : Issuing a forward immediately exits the current route, and
perform the forward. Thus, any code after a forward is ignored, until
the end of the route. e.g.
get '/foo/:article_id' => sub {
if ($condition) {
forward "/articles/" . params->{article_id};
# The following code is never executed
do_stuff();
}
more_stuff();
};
So it's not necessary anymore to use return with forward.
Note that forward doesn't parse GET arguments. So, you can't use
something like:
return forward '/home?authorized=1';
But forward supports an optional HashRef with parameters to be added to
the actual parameters:
return forward '/home', { authorized => 1 };
Finally, you can add some more options to the forward method, in a
third argument, also as a HashRef. That option is currently only used
to change the method of your request. Use with caution.
return forward '/home', { auth => 1 }, { method => 'POST' };
from_dumper ($structure)
Deserializes a Data::Dumper structure.
from_json ($structure, %options)
Deserializes a JSON structure. Can receive optional arguments. Those
arguments are valid JSON arguments to change the behaviour of the
default JSON::from_json function.
from_yaml ($structure)
Deserializes a YAML structure.
from_xml ($structure, %options)
Deserializes a XML structure. Can receive optional arguments. These
arguments are valid XML::Simple arguments to change the behaviour of
the default XML::Simple::XMLin function.
get
Defines a route for HTTP GET requests to the given path:
get '/' => sub {
return "Hello world";
}
Note that a route to match HEAD requests is automatically created as
well.
halt
Sets a response object with the content given.
When used as a return value from a filter, this breaks the execution
flow and renders the response immediately:
hook before sub {
if ($some_condition) {
halt("Unauthorized");
# This code is not executed :
do_stuff();
}
};
get '/' => sub {
"hello there";
};
WARNING : Issuing a halt immediately exits the current route, and
perform the halt. Thus, any code after a halt is ignored, until the end
of the route. So it's not necessary anymore to use return with halt.
headers
Adds custom headers to responses:
get '/send/headers', sub {
headers 'X-Foo' => 'bar', X-Bar => 'foo';
}
header
adds a custom header to response:
get '/send/header', sub {
header 'x-my-header' => 'shazam!';
}
Note that it will overwrite the old value of the header, if any. To
avoid that, see "push_header".
push_header
Do the same as header, but allow for multiple headers with the same
name.
get '/send/header', sub {
push_header 'x-my-header' => '1';
push_header 'x-my-header' => '2';
will result in two headers "x-my-header" in the response
}
hook
Adds a hook at some position. For example :
hook before_serializer => sub {
my $response = shift;
$response->content->{generated_at} = localtime();
};
There can be multiple hooks assigned to a given position, and each will
be executed in order. Note that all hooks are always called, even if
they are defined in a different package loaded via load_app.
(For details on how to register new hooks from within plugins, see
Dancer::Hook.) Supported before hooks (in order of execution):
before_deserializer
This hook receives no arguments.
hook before_deserializer => sub {
...
};
before_file_render
This hook receives as argument the path of the file to render.
hook before_file_render => sub {
my $path = shift;
...
};
before_error_init
This hook receives as argument a Dancer::Error object.
hook before_error_init => sub {
my $error = shift;
...
};
before_error_render
This hook receives as argument a Dancer::Error object.
hook before_error_render => sub {
my $error = shift;
};
before
This hook receives one argument, the route being executed (a
Dancer::Route object).
hook before => sub {
my $route_handler = shift;
...
};
it is equivalent to the deprecated
before sub {
...
};
before_template_render
This is an alias to 'before_template'.
This hook receives as argument a HashRef containing the tokens that
will be passed to the template. You can use it to add more tokens, or
delete some specific token.
hook before_template_render => sub {
my $tokens = shift;
delete $tokens->{user};
$tokens->{time} = localtime;
};
is equivalent to
hook before_template => sub {
my $tokens = shift;
delete $tokens->{user};
$tokens->{time} = localtime;
};
before_layout_render
This hook receives two arguments. The first one is a HashRef
containing the tokens. The second is a ScalarRef representing the
content of the template.
hook before_layout_render => sub {
my ($tokens, $html_ref) = @_;
...
};
before_serializer
This hook receives as argument a Dancer::Response object.
hook before_serializer => sub {
my $response = shift;
$response->content->{start_time} = time();
};
Supported after hooks (in order of execution):
after_deserializer
This hook receives no arguments.
hook after_deserializer => sub {
...
};
after_file_render
This hook receives as argument a Dancer::Response object.
hook after_file_render => sub {
my $response = shift;
};
after_template_render
This hook receives as argument a ScalarRef representing the content
generated by the template.
hook after_template_render => sub {
my $html_ref = shift;
};
after_layout_render
This hook receives as argument a ScalarRef representing the content
generated by the layout
hook after_layout_render => sub {
my $html_ref = shift;
};
after
This is an alias for after.
This hook runs after a request has been processed, but before the
response is sent.
It receives a Dancer::Response object, which it can modify if it
needs to make changes to the response which is about to be sent.
hook after => sub {
my $response = shift;
};
This is equivalent to the deprecated
after sub {
my $response = shift;
};
after_error_render
This hook receives as argument a Dancer::Response object.
hook after_error_render => sub {
my $response = shift;
};
on_handler_exception
This hook is called when an exception has been caught, at the handler
level, just before creating and rendering Dancer::Error. This hook
receives as argument a Dancer::Exception object.
hook on_handler_exception => sub {
my $exception = shift;
};
on_reset_state
This hook is called when global state is reset to process a new
request. It receives a boolean value that indicates whether the reset
was called as part of a forwarded request.
hook on_reset_state => sub {
my $is_forward = shift;
};
on_route_exception
This hook is called when an exception has been caught, at the route
level, just before rethrowing it higher. This hook receives the
exception as argument. It can be a Dancer::Exception, or a string, or
whatever was used to die.
hook on_route_exception => sub {
my $exception = shift;
};
info
Logs a message of info level:
info "This is a info message";
See Dancer::Logger for details on how to configure where log messages
go.
layout
This method is deprecated. Use set:
set layout => 'user';
logger
Deprecated. Use <set logger => 'console'> to change current logger
engine.
load
Loads one or more perl scripts in the current application's namespace.
Syntactic sugar around Perl's require:
load 'UserActions.pl', 'AdminActions.pl';
load_app
Loads a Dancer package. This method sets the libdir to the current
./lib directory:
# if we have lib/Webapp.pm, we can load it like:
load_app 'Webapp';
# or with options
load_app 'Forum', prefix => '/forum', settings => {foo => 'bar'};
Note that the package loaded using load_app must import Dancer with the
:syntax option.
To load multiple apps repeat load_app:
load_app 'one';
load_app 'two';
The old way of loading multiple apps in one go (load_app 'one', 'two';)
is deprecated.
mime
Shortcut to access the instance object of Dancer::MIME. You should read
the Dancer::MIME documentation for full details, but the most
commonly-used methods are summarized below:
# set a new mime type
mime->add_type( foo => 'text/foo' );
# set a mime type alias
mime->add_alias( f => 'foo' );
# get mime type for an alias
my $m = mime->for_name( 'f' );
# get mime type for a file (based on extension)
my $m = mime->for_file( "foo.bar" );
# get current defined default mime type
my $d = mime->default;
# set the default mime type using config.yml
# or using the set keyword
set default_mime_type => 'text/plain';
params
This method should be called from a route handler. It's an alias for
the Dancer::Request params accessor. In list context it returns a list
of key/value pair of all defined parameters. In scalar context it
returns a hash reference instead. Check param below to access quickly
to a single parameter value.
param
This method should be called from a route handler. This method is an
accessor to the parameters hash table.
post '/login' => sub {
my $username = param "user";
my $password = param "pass";
# ...
}
param_array
This method should be called from a route handler. Like param, but
always returns the parameter value or values as a list. Returns the
number of values in scalar context.
# if request is '/tickets?tag=open&tag=closed&order=desc'...
get '/tickets' => sub {
my @tags = param_array 'tag'; # ( 'open', 'closed' )
my $tags = param 'tag'; # array ref
my @order = param_array 'order'; # ( 'desc' )
my $order = param 'order'; # 'desc'
};
pass
This method should be called from a route handler. Tells Dancer to pass
the processing of the request to the next matching route.
WARNING : Issuing a pass immediately exits the current route, and
performs the pass. Thus, any code after a pass is ignored until the end
of the route. So it's not necessary any more to use return with pass.
get '/some/route' => sub {
if (...) {
# we want to let the next matching route handler process this one
pass(...);
# This code will be ignored
do_stuff();
}
};
patch
Defines a route for HTTP PATCH requests to the given URL:
patch '/resource' => sub { ... };
(PATCH is a relatively new and not-yet-common HTTP verb, which is
intended to work as a "partial-PUT", transferring just the changes;
please see http://tools.ietf.org/html/rfc5789|RFC5789 for further
details.)
Please be aware that, if you run your app in standalone mode, PATCH
requests will not reach your app unless you have a new version of
HTTP::Server::Simple which accepts PATCH as a valid verb. The current
version at time of writing, 0.44, does not. A pull request has been
submitted to add this support, which you can find at:
https://github.com/bestpractical/http-server-simple/pull/1
path
Concatenates multiple paths together, without worrying about the
underlying operating system:
my $path = path(dirname($0), 'lib', 'File.pm');
It also normalizes (cleans) the path aesthetically. It does not verify
the path exists.
post
Defines a route for HTTP POST requests to the given URL:
post '/' => sub {
return "Hello world";
}
prefix
Defines a prefix for each route handler, like this:
prefix '/home';
From here, any route handler is defined to /home/*:
get '/page1' => sub {}; # will match '/home/page1'
You can unset the prefix value:
prefix undef;
get '/page1' => sub {}; will match /page1
For a safer alternative you can use lexical prefix like this:
prefix '/home' => sub {
## Prefix is set to '/home' here
get ...;
get ...;
};
## prefix reset to the previous version here
This makes it possible to nest prefixes:
prefix '/home' => sub {
## some routes
prefix '/private' => sub {
## here we are under /home/private...
## some more routes
};
## back to /home
};
## back to the root
Notice: once you have a prefix set, do not add a caret to the regex:
prefix '/foo';
get qr{^/bar} => sub { ... } # BAD BAD BAD
get qr{/bar} => sub { ... } # Good!
del
Defines a route for HTTP DELETE requests to the given URL:
del '/resource' => sub { ... };
options
Defines a route for HTTP OPTIONS requests to the given URL:
options '/resource' => sub { ... };
put
Defines a route for HTTP PUT requests to the given URL:
put '/resource' => sub { ... };
redirect
Generates an HTTP redirect (302). You can either redirect to a
completely different site or within the application:
get '/twitter', sub {
redirect 'http://twitter.com/me';
};
You can also force Dancer to return a specific 300-ish HTTP response
code:
get '/old/:resource', sub {
redirect '/new/'.params->{resource}, 301;
};
It is important to note that issuing a redirect by itself does not exit
and redirect immediately. Redirection is deferred until after the
current route or filter has been processed. To exit and redirect
immediately, use the return function, e.g.
get '/restricted', sub {
return redirect '/login' if accessDenied();
return 'Welcome to the restricted section';
};
render_with_layout
Allows a handler to provide plain HTML (or other content), but have it
rendered within the layout still.
This method is DEPRECATED, and will be removed soon. Instead, you
should be using the engine keyword:
get '/foo' => sub {
# Do something which generates HTML directly (maybe using
# HTML::Table::FromDatabase or something)
my $content = ...;
# get the template engine
my $template_engine = engine 'template';
# apply the layout (not the renderer), and return the result
$template_engine->apply_layout($content)
};
It works very similarly to template in that you can pass tokens to be
used in the layout, and/or options to control the way the layout is
rendered. For instance, to use a custom layout:
render_with_layout $content, {}, { layout => 'layoutname' };
request
Returns a Dancer::Request object representing the current request.
See the Dancer::Request documentation for the methods you can call, for
example:
request->referer; # value of the HTTP referer header
request->remote_address; # user's IP address
request->user_agent; # User-Agent header value
send_error
Returns an HTTP error. By default the HTTP code returned is 500:
get '/photo/:id' => sub {
if (...) {
send_error("Not allowed", 403);
} else {
# return content
}
}
WARNING : Issuing a send_error immediately exits the current route, and
perform the send_error. Thus, any code after a send_error is ignored,
until the end of the route. So it's not necessary anymore to use return
with send_error.
get '/some/route' => sub {
if (...) {
# we want to let the next matching route handler process this one
send_error(..);
# This code will be ignored
do_stuff();
}
};
send_file
Lets the current route handler send a file to the client. Note that the
path of the file must be relative to the public directory unless you
use the system_path option (see below).
get '/download/:file' => sub {
send_file(params->{file});
}
WARNING : Issuing a send_file immediately exits the current route, and
performs the send_file. Thus, any code after a send_file is ignored
until the end of the route. So it's not necessary any more to use
return with send_file.
get '/some/route' => sub {
if (...) {
# we want to let the next matching route handler process this one
send_file(...);
# This code will be ignored
do_stuff();
}
};
Send file supports streaming possibility using PSGI streaming. The
server should support it but normal streaming is supported on most, if
not all.
get '/download/:file' => sub {
send_file( params->{file}, streaming => 1 );
}
You can control what happens using callbacks.
First, around_content allows you to get the writer object and the chunk
of content read, and then decide what to do with each chunk:
get '/download/:file' => sub {
send_file(
params->{file},
streaming => 1,
callbacks => {
around_content => sub {
my ( $writer, $chunk ) = @_;
$writer->write("* $chunk");
},
},
);
}
You can use around to all get all the content (whether a filehandle if
it's a regular file or a full string if it's a scalar ref) and decide
what to do with it:
get '/download/:file' => sub {
send_file(
params->{file},
streaming => 1,
callbacks => {
around => sub {
my ( $writer, $content ) = @_;
# we know it's a text file, so we'll just stream
# line by line
while ( my $line = <$content> ) {
$writer->write($line);
}
},
},
);
}
Or you could use override to control the entire streaming callback
request:
get '/download/:file' => sub {
send_file(
params->{file},
streaming => 1,
callbacks => {
override => sub {
my ( $respond, $response ) = @_;
my $writer = $respond->( [ $newstatus, $newheaders ] );
$writer->write("some line");
},
},
);
}
You can also set the number of bytes that will be read at a time
(default being 42K bytes) using bytes:
get '/download/:file' => sub {
send_file(
params->{file},
streaming => 1,
bytes => 524288, # 512K
);
};
The content-type will be set depending on the current MIME types
definition (see mime if you want to define your own).
If your filename does not have an extension, or you need to force a
specific mime type, you can pass it to send_file as follows:
send_file(params->{file}, content_type => 'image/png');
Also, you can use your aliases or file extension names on content_type,
like this:
send_file(params->{file}, content_type => 'png');
For files outside your public folder, you can use the system_path
switch. Just bear in mind that its use needs caution as it can be
dangerous.
send_file('/etc/passwd', system_path => 1);
If you have your data in a scalar variable, send_file can be useful as
well. Pass a reference to that scalar, and send_file will behave as if
there were a file with that contents:
send_file( \$data, content_type => 'image/png' );
Note that Dancer is unable to guess the content type from the data
contents. Therefore you might need to set the content_type properly.
For this kind of usage an attribute named filename can be useful. It is
used as the Content-Disposition header, to hint the browser about the
filename it should use.
send_file( \$data, content_type => 'image/png'
filename => 'onion.png' );
set
Defines a setting:
set something => 'value';
You can set more than one value at once:
set something => 'value', otherthing => 'othervalue';
setting
Returns the value of a given setting:
setting('something'); # 'value'
set_cookie
Creates or updates cookie values:
get '/some_action' => sub {
set_cookie name => 'value',
expires => (time + 3600),
domain => '.foo.com';
};
In the example above, only 'name' and 'value' are mandatory.
You can also store more complex structure in your cookies:
get '/some_auth' => sub {
set_cookie oauth => {
token => $twitter->request_token,
token_secret => $twitter->secret_token,
...
};
};
You can't store more complex structure than this. All keys in the
HashRef should be Scalars; storing references will not work.
See Dancer::Cookie for further options when creating your cookie.
Note that this method will be eventually deprecated in favor of the new
cookie method.
session
Provides access to all data stored in the user's session (if any).
It can also be used as a setter to store data in the session:
# getter example
get '/user' => sub {
if (session('user')) {
return "Hello, ".session('user')->name;
}
};
# setter example
post '/user/login' => sub {
...
if ($logged_in) {
session user => $user;
}
...
};
You may also need to clear a session:
# destroy session
get '/logout' => sub {
...
session->destroy;
...
};
If you need to fetch the session ID being used for any reason:
my $id = session->id;
In order to be able to use sessions, first you need to enable session
support in one of the configuration files. A quick way to do it is to
add
session: "YAML"
to config.yml.
For more details, see Dancer::Session.
splat
Returns the list of captures made from a route handler with a route
pattern which includes wildcards:
get '/file/*.*' => sub {
my ($file, $extension) = splat;
...
};
There is also the extensive splat (A.K.A. "megasplat"), which allows
extensive greedier matching, available using two asterisks. The
additional path is broken down and returned as an ArrayRef:
get '/entry/*/tags/**' => sub {
my ( $entry_id, $tags ) = splat;
my @tags = @{$tags};
};
This helps with chained actions:
get '/team/*/**' => sub {
my ($team) = splat;
var team => $team;
pass;
};
prefix '/team/*';
get '/player/*' => sub {
my ($player) = splat;
# etc...
};
get '/score' => sub {
return score_for( vars->{'team'} );
};
start
Starts the application or the standalone server (depending on the
deployment choices).
This keyword should be called at the very end of the script, once all
routes are defined. At this point, Dancer takes over control.
status
Changes the status code provided by an action. By default, an action
will produce an HTTP 200 OK status code, meaning everything is OK:
get '/download/:file' => {
if (! -f params->{file}) {
status 'not_found';
return "File does not exist, unable to download";
}
# serving the file...
};
In that example Dancer will notice that the status has changed, and
will render the response accordingly.
The status keyword receives either a numeric status code or its name in
lower case, with underscores as a separator for blanks. See the list in
"HTTP CODES" in Dancer::HTTP.
template
Returns the response of processing the given template with the given
parameters (and optional settings), wrapping it in the default or
specified layout too, if layouts are in use.
An example of a route handler which returns the result of using
template to build a response with the current template engine:
get '/' => sub {
...
return template 'some_view', { token => 'value'};
};
Note that template simply returns the content, so when you use it in a
route handler, if execution of the route handler should stop at that
point, make sure you use 'return' to ensure your route handler returns
the content.
Since template just returns the result of rendering the template, you
can also use it to perform other templating tasks, e.g. generating
emails:
post '/some/route' => sub {
if (...) {
email {
to => 'someone@example.com',
from => 'foo@example.com',
subject => 'Hello there',
msg => template('emails/foo', { name => params->{name} }),
};
return template 'message_sent';
} else {
return template 'error';
}
};
Compatibility notice: template was changed in version 1.3090 to
immediately interrupt execution of a route handler and return the
content, as it's typically used at the end of a route handler to return
content. However, this caused issues for some people who were using
template to generate emails etc, rather than accessing the template
engine directly, so this change has been reverted in 1.3091.
The first parameter should be a template available in the views
directory, the second one (optional) is a HashRef of tokens to
interpolate, and the third (again optional) is a HashRef of options.
For example, to disable the layout for a specific request:
get '/' => sub {
template 'index', {}, { layout => undef };
};
Or to request a specific layout, of course:
get '/user' => sub {
template 'user', {}, { layout => 'user' };
};
Some tokens are automatically added to your template (perl_version,
dancer_version, settings, request, params, vars and, if you have
sessions enabled, session). Check Dancer::Template::Abstract for
further details.
to_dumper ($structure)
Serializes a structure with Data::Dumper.
to_json ($structure, %options)
Serializes a structure to JSON. Can receive optional arguments. Thoses
arguments are valid JSON arguments to change the behaviour of the
default JSON::to_json function.
to_yaml ($structure)
Serializes a structure to YAML.
to_xml ($structure, %options)
Serializes a structure to XML. Can receive optional arguments. Thoses
arguments are valid XML::Simple arguments to change the behaviour of
the default XML::Simple::XMLout function.
true
Constant that returns a true value (1).
upload
Provides access to file uploads. Any uploaded file is accessible as a
Dancer::Request::Upload object. You can access all parsed uploads via:
post '/some/route' => sub {
my $file = upload('file_input_foo');
# file is a Dancer::Request::Upload object
};
If you named multiple inputs of type "file" with the same name, the
upload keyword will return an Array of Dancer::Request::Upload objects:
post '/some/route' => sub {
my ($file1, $file2) = upload('files_input');
# $file1 and $file2 are Dancer::Request::Upload objects
};
You can also access the raw HashRef of parsed uploads via the current
request object:
post '/some/route' => sub {
my $all_uploads = request->uploads;
# $all_uploads->{'file_input_foo'} is a Dancer::Request::Upload object
# $all_uploads->{'files_input'} is an ArrayRef of Dancer::Request::Upload objects
};
Note that you can also access the filename of the upload received via
the params keyword:
post '/some/route' => sub {
# params->{'files_input'} is the filename of the file uploaded
};
See Dancer::Request::Upload for details about the interface provided.
uri_for
Returns a fully-qualified URI for the given path:
get '/' => sub {
redirect uri_for('/path');
# can be something like: http://localhost:3000/path
};
captures
Returns a reference to a copy of %+, if there are named captures in the
route Regexp.
Named captures are a feature of Perl 5.10, and are not supported in
earlier versions:
get qr{
/ (?<object> user | ticket | comment )
/ (?<action> delete | find )
/ (?<id> \d+ )
/?$
}x
, sub {
my $value_for = captures;
"i don't want to $$value_for{action} the $$value_for{object} $$value_for{id} !"
};
var
Provides an accessor for variables shared between filters and route
handlers. Given a key/value pair, it sets a variable:
hook before sub {
var foo => 42;
};
Later, route handlers and other filters will be able to read that
variable:
get '/path' => sub {
my $foo = var 'foo';
...
};
vars
Returns the HashRef of all shared variables set during the filter/route
chain with the var keyword:
get '/path' => sub {
if (vars->{foo} eq 42) {
...
}
};
warning
Logs a warning message through the current logger engine:
warning "This is a warning";
See Dancer::Logger for details on how to configure where log messages
go.
AUTHOR
This module has been written by Alexis Sukrieh <sukria@cpan.org> and
others, see the AUTHORS file that comes with this distribution for
details.
SOURCE CODE
The source code for this module is hosted on GitHub
https://github.com/PerlDancer/Dancer. Feel free to fork the repository
and submit pull requests! (See Dancer::Development for details on how
to contribute).
Also, why not watch the repo
<https://github.com/PerlDancer/Dancer/toggle_watch> to keep up to date
with the latest upcoming changes?
GETTING HELP / CONTRIBUTING
The Dancer development team can be found on #dancer on irc.perl.org:
irc://irc.perl.org/dancer
If you don't have an IRC client installed/configured, there is a simple
web chat client at http://www.perldancer.org/irc for you.
There is also a Dancer users mailing list available. Subscribe at:
http://lists.preshweb.co.uk/mailman/listinfo/dancer-users
If you'd like to contribute to the Dancer project, please see
http://www.perldancer.org/contribute for all the ways you can help!
DEPENDENCIES
The following modules are mandatory (Dancer cannot run without them):
HTTP::Server::Simple::PSGI
HTTP::Tiny
MIME::Types
URI
The following modules are optional:
JSON : needed to use JSON serializer
Plack : in order to use PSGI
Template : in order to use TT for rendering views
XML::Simple and XML:SAX or XML:Parser for XML serialization
YAML : needed for configuration file support
SEE ALSO
Main Dancer web site: http://perldancer.org/.
The concept behind this module comes from the Sinatra ruby project, see
http://www.sinatrarb.com/ for details.