Dancer::Plugin::Swagger - create Swagger documentation of the app REST interface


version 0.3.0


    package MyApp;

    use Dancer;
    use Dancer::Plugin::Swagger;

    our $VERSION = "0.1";

    get '/choreograph/:name' => sub { ... };



This plugin provides tools to create and access a Swagger specification file for a Dancer REST web service.

Overview of Dancer::Plugin::Swagger's features:

Can create a /swagger.json REST specification file.
Can auto-discover routes and add them to the swagger file.
Can provide a Swagger UI version of the swagger documentation.


           main_api_module: MyApp
           show_ui: 1
           ui_url: /doc
           ui_dir: /path/to/files
            - /swagger.json
            - qr#^/doc/#


If not provided explicitly, the Swagger document's title and version will be set to the abstract and version of this module.

Defaults to the first module to import Dancer::Plugin::Swagger.


If true, a route will be created for the Swagger UI (see

Defaults to true.


Path of the swagger ui route. Will also be the prefix for all the CSS/JS dependencies of the page.

Defaults to /doc.


Filesystem path to the directory holding the assets for the Swagger UI page.

Defaults to a copy of the Swagger UI code bundled with the Dancer::Plugin::Swagger distribution.


List of urls that should not be added to the Swagger document by swagger_auto_discover. If an url begins with qr, it will be compiled as a regular expression.

Defauls to /swagger.json and, if show_ui is true, all the urls under ui_url.


If set to true, calls to swagger_response will verify if a schema is defined for the response, and if so validate against it. JSON::Schema::AsType is used for the validation (and this required if this option is used).

Defaults to false.


If set to true, dies if a call to swagger_response doesn't find a schema for its response.

Defaults to false.


swagger_path $description, \%args, $route

    swagger_path {
        description => 'Returns info about a judge',
    get '/judge/:judge_name' => sub {

Registers a route as a swagger path item in the swagger document.

%args is optional.

The $description is optional as well, and can also be defined as part of the %args.

    # equivalent to the main example
    swagger_path 'Returns info about a judge',
    get '/judge/:judge_name' => sub {

If the $description spans many lines, it will be left-trimmed.

    swagger_path q{ 
        Returns info about a judge.

        Some more documentation can go here.

            And this will be seen as a performatted block
            by swagger.
    get '/judge/:judge_name' => sub {

Supported arguments


The HTTP method (GET, POST, etc) for the path item.

Defaults to the route's method.


The url for the path item.

Defaults to the route's path.


The path item's description.


Optional arrayref of tags assigned to the path.


List of parameters for the path item. Must be an arrayref or a hashref.

Route parameters are automatically populated. E.g.,

    get '/judge/:judge_name' => { ... };

is equivalent to

    swagger_path {
        parameters => [
            { name => 'judge_name', in => 'path', required => 1, type => 'string' },
    get '/judge/:judge_name' => { ... };

If the parameters are passed as a hashref, the keys are the names of the parameters, and they will appear in the swagger document following their alphabetical order.

If the parameters are passed as an arrayref, they will appear in the document in the order in which they are passed. Additionally, each parameter can be given as a hashref, or can be a name => arguments pair.

In both format, for the key/value pairs, a string value is considered to be the description of the parameter.

Finally, if not specified explicitly, the in argument of a parameter defaults to query, and its type to string.

    parameters => [
        { name => 'bar', in => 'path', required => 1, type => 'string' },
        { name => 'foo', in => 'query', type => 'string', description => 'yadah' },

    # equivalent arrayref with mixed pairs/non-pairs

    parameters => [
        { name => 'bar', in => 'path', required => 1, type => 'string' },
        foo => { in => 'query', type => 'string', description => 'yadah' },

    # equivalent hashref format 
    parameters => {
        bar => { in => 'path', required => 1, type => 'string' },
        foo => { in => 'query', type => 'string', description => 'yadah' },

    # equivalent, using defaults
    parameters => {
        bar => { in => 'path', required => 1 },
        foo => 'yadah',

Possible responses from the path. Must be a hashref.

    swagger_path {
        responses => {
            default => { description => 'The judge information' }
    get '/judge/:judge_name' => { ... };

If the key example is given (instead of examples as defined by the Swagger specs), and the serializer used by the application is Dancer::Serializer::JSON or Dancer::Serializer::YAML, the example will be expanded to have the right content-type key.

    swagger_path {
        responses => {
            default => { example => { fullname => 'Mary Ann Murphy' } }
    get '/judge/:judge_name' => { ... };

    # equivalent to

    swagger_path {
        responses => {
            default => { examples => { 'application/json' => { fullname => 'Mary Ann Murphy' } } }
    get '/judge/:judge_name' => { ... };

The special key template will not appear in the Swagger doc, but will be used by the swagger_template plugin keyword.

swagger_template $code, $args

    swagger_path {
        responses => {
            404 => { template => sub { +{ error => "judge '$_[0]' not found" } }  
    get '/judge/:judge_name' => {  
        my $name = param('judge_name');
        return swagger_template 404, $name unless in_db($name);

Calls the template for the $code response, passing it $args. If $code is numerical, also set the response's status to that value.

swagger_auto_discover skip => \@list

Populates the Swagger document with information of all the routes of the application.

Accepts an optional skip parameter that takes an arrayref of routes that shouldn't be added to the Swagger document. The routes can be specified as-is, or via regular expressions. If no skip list is given, defaults to the c<auto_discover_skip> configuration value.

    swagger_auto_discover skip => [ '/swagger.json', qr#^/doc/# ];

The information of a route won't be altered if it's already present in the document.

If a route has path parameters, they will be automatically added as such in the parameters section.

Routes defined as regexes are skipped, as there is no clean way to automatically make them look nice.

        # will be picked up
    get '/user' => ...;

        # ditto, as '/user/{user_id}'
    get '/user/:user_id => ...;

        # won't be picked up
    get qr#/user/(\d+)# => ...;

Note that routes defined after swagger_auto_discover has been called won't be added to the Swagger document. Typically, you'll want swagger_auto_discover to be called at the very end of your module. Alternatively, swagger_auto_discover can be called more than once safely -- which can be useful if an application creates routes dynamically.

swagger_definition $name => $definition, ...

Adds a schema (or more) to the definition section of the Swagger document.

    swagger_definition 'Judge' => {
        type => 'object',
        required => [ 'fullname' ],
        properties => {
            fullname => { type => 'string' },
            seasons => { type => 'array', items => { type => 'integer' } },

The function returns the reference to the definition that can be then used where schemas are used.

    my $Judge = swagger_definition 'Judge' => { ... };
    # $Judge is now the hashref '{ '$ref' => '#/definitions/Judge' }'
    # later on...
    swagger_path {
        responses => {
            default => { schema => $Judge },
    get '/judge/:name' => sub { ... };


See the examples/ directory of the distribution for a working example.

SEE ALSO|Swagger


Yanick Champoux <>


This software is copyright (c) 2021, 2016, 2015 by Yanick Champoux.

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