NAME

Dancer - lightweight yet powerful web application framework

VERSION

version 1.3521

SYNOPSIS

#!/usr/bin/perluse 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 theDancer::Introduction and theDancer::Cookbook. For examples on deploying your Dancer applications, seeDancer::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 atDancer::Introduction, orDancer::Tutorial to learn by example.

If you want to have specific examples of code for real-life problems, see theDancer::Cookbook.

If you want to see configuration examples of different deployment solutions involving Dancer and Plack, seeDancer::Deployment.

You can find out more about the many useful plugins available for Dancer inDancer::Plugins.

DANCER 2

This is the original version of Dancer, which is now in maintenance mode. This means that it will not receive significant new features, but will continue to receive bugfixes and security fixes. However, no "end of life" date has been set, and it is expected that this version of Dancer will continue to receive bugfixes and security fixes for quite some time yet.

However, you should consider migrating toDancer2 instead when you can, and are advised to use Dancer2 for newly-started apps.

Dancer2 is mostly backwards compatible, but has been re-written from the ground up to be more maintainable and extensible, and is the future of Dancer.

Dancer2::Manual::Migration covers the changes you should be aware of when migrating an existing Dancer 1 powered app to Dancer 2.

EXPORTS

By default,use Dancer exports all the functions below plus sets up your app. You can control the exporting through the normalExporter mechanism. For example:

# Just export the route controllersuse Dancer qw(get post put patch del);# Export everything but pass to avoid clashing with Test::Moreuse Test::More;use Dancer qw(!pass);

Please note that theutf8 andstrict pragmas are exported by this module.

By default, thewarnings pragma will also be exported, meaning your app/script will be running underuse warnings. If you do not want this, set theglobal_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 areafter andbefore.

: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 arepass.

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 viaDancer::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 ofuse 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 ofsession.

FUNCTIONS

after

Deprecated - see theafterhook.

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 thebeforehook.

before_template

Deprecated - see thebefore_templatehook.

cookies

Accesses cookies values, it returns a HashRef ofDancer::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 overset_cookie.

cookie lang => "fr-FR";              # set a cookie and return its valuecookie lang => "fr-FR", expires => "2 hours";   # extra cookie infocookie "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 thecontent-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 thecontent_type setting instead.

dance

Alias for thestart 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";

SeeDancer::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";

SeeDancer::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 wasGET orPOST. That is becauseforward chains the same type of route the user reached. If it was aGET, it will remain aGET (but if you do need to change the method, you can do so; read on below for details.)

WARNING : using forward willnot 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 usereturn with forward.

Note that forward doesn't parse GET arguments. So, you can't use something like:

return forward '/home?authorized=1';

Butforward 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 aData::Dumper structure.

from_json ($structure, \%options)

Deserializes a JSON structure. Can receive optional arguments. Those arguments are validJSON arguments to change the behaviour of the defaultJSON::from_json function.

Compatibility notice:from_json changed in 1.3002 to take a hashref as options, instead of a hash.

from_yaml ($structure)

Deserializes a YAML structure.

from_xml ($structure, %options)

Deserializes a XML structure. Can receive optional arguments. These arguments are validXML::Simple arguments to change the behaviour of the defaultXML::Simple::XMLin function.

get

Defines a route for HTTPGET requests to the given path:

get '/' => sub {    return "Hello world";}

Note that a route to matchHEAD 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 usereturn 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 asheader, 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 thatall hooks are always called, even if they are defined in a different package loaded viaload_app.

(For details on how to register new hooks from within plugins, seeDancer::Hook.) Supportedbefore 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 aDancer::Error object.

hook before_error_init => sub {  my $error = shift;  ...};

before_error_render

This hook receives as argument aDancer::Error object.

hook before_error_render => sub {  my $error = shift;};

before

This hook receives one argument, the route being executed (aDancer::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 aDancer::Response object.

hook before_serializer => sub {  my $response = shift;  $response->content->{start_time} = time();};

Supportedafter hooks (in order of execution):

after_deserializer

This hook receives no arguments.

hook after_deserializer => sub {  ...};

after_file_render

This hook receives as argument aDancer::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 forafter.

This hook runs after a request has been processed, but before the response is sent.

It receives aDancer::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 aDancer::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 renderingDancer::Error. This hook receives as argument aDancer::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 todie.

hook on_route_exception => sub {  my $exception = shift;};

info

Logs a message of info level:

info "This is a info message";

SeeDancer::Logger for details on how to configure where log messages go.

layout

This method is deprecated. Useset:

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'srequire:

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 optionsload_app 'Forum', prefix => '/forum', settings => {foo => 'bar'};

Note that the package loaded using load_appmust 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 ofDancer::MIME. You should read theDancer::MIME documentation for full details, but the most commonly-used methods are summarized below:

# set a new mime typemime->add_type( foo => 'text/foo' );# set a mime type aliasmime->add_alias( f => 'foo' );# get mime type for an aliasmy $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 typemy $d = mime->default;# set the default mime type using config.yml# or using the set keywordset default_mime_type => 'text/plain';

params

This method should be called from a route handler. It's an alias for theDancer::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. Checkparam 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. Likeparam, 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 usereturn 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 HTTPPATCH 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 seehttp://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 ofHTTP::Server::Simple which acceptsPATCH 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 HTTPPOST 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 BADget qr{/bar}  => sub { ... } # Good!

del

Defines a route for HTTPDELETE requests to the given URL:

del '/resource' => sub { ... };

options

Defines a route for HTTPOPTIONS requests to the given URL:

options '/resource' => sub { ... };

put

Defines a route for HTTPPUT 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 isDEPRECATED, and will be removed soon. Instead, you should be using theengine 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 totemplate 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 aDancer::Request object representing the current request.

See theDancer::Request documentation for the methods you can call, for example:

request->referer;         # value of the HTTP referer headerrequest->remote_address;  # user's IP addressrequest->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 usereturn 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 thepublic directory unless you use thesystem_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 usereturn 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 usearound 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 useoverride 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) usingbytes:

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 (seemime 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 tosend_file as follows:

send_file(params->{file}, content_type => 'image/png');

Also, you can use your aliases or file extension names oncontent_type, like this:

send_file(params->{file}, content_type => 'png');

For files outside yourpublic folder, you can use thesystem_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, andsend_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 thecontent_type properly. For this kind of usage an attribute namedfilename 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.

SeeDancer::Cookie for further options when creating your cookie.

Note that this method will be eventually deprecated in favor of the newcookie 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 exampleget '/user' => sub {    if (session('user')) {        return "Hello, ".session('user')->name;    }};# setter examplepost '/user/login' => sub {    ...    if ($logged_in) {        session user => $user;    }    ...};

You may also need to clear a session:

# destroy sessionget '/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, seeDancer::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 anHTTP 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 thattemplate 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 usingtemplate 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). CheckDancer::Template::Abstract for further details.

to_dumper ($structure)

Serializes a structure withData::Dumper.

to_json ($structure, \%options)

Serializes a structure to JSON. Can receive optional arguments. Thoses arguments are validJSON arguments to change the behaviour of the defaultJSON::to_json function.

Compatibility notice:to_json changed in 1.3002 to take a hashref as options, instead of a hash.

to_yaml ($structure)

Serializes a structure to YAML.

to_xml ($structure, %options)

Serializes a structure to XML. Can receive optional arguments. Thoses arguments are validXML::Simple arguments to change the behaviour of the defaultXML::Simple::XMLout function.

true

Constant that returns a true value (1).

upload

Provides access to file uploads. Any uploaded file is accessible as aDancer::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};

SeeDancer::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};

Querystring parameters can be provided by passing a hashref as a second param, and URL-encoding can be disabled via a third parameter:

uri_for('/path', { foo => 'bar' }, 1);# would return e.g. http://localhost:3000/path?foo=bar

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 thevar keyword:

get '/path' => sub {    if (vars->{foo} eq 42) {        ...    }};

warning

Logs a warning message through the current logger engine:

warning "This is a warning";

SeeDancer::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 GitHubhttps://github.com/PerlDancer/Dancer. Feel free to fork the repository and submit pull requests! (SeeDancer::Development for details on how to contribute).

Also, why notwatch the repo 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 athttp://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 seehttp://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 andXML:SAX orXML: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, seehttp://www.sinatrarb.com/ for details.

AUTHOR

Dancer Core Developers

COPYRIGHT AND LICENSE

This software is copyright (c) 2010 by Alexis Sukrieh.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.