OpenAPI / Swagger plugin for Mojolicious
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Mojolicious::Plugin::OpenAPI - OpenAPI / Swagger plugin for Mojolicious


use Mojolicious::Lite;

# Will be moved under "basePath", resulting in "POST /api/echo"
post "/echo" => sub {

  # Validate input request or return an error document
  my $c = shift->openapi->valid_input or return;

  # Generate some data
  my $data = {body => $c->validation->param("body")};

  # Validate the output response and render it to the user agent
  # using a custom "openapi" handler.
  $c->render(openapi => $data);
}, "echo";

# Load specification and start web server
plugin OpenAPI => {url => "data://main/api.json"};

@@ api.json
  "swagger" : "2.0",
  "info" : { "version": "0.8", "title" : "Pets" },
  "schemes" : [ "http" ],
  "basePath" : "/api",
  "paths" : {
    "/echo" : {
      "post" : {
        "x-mojo-name" : "echo",
        "parameters" : [
          { "in": "body", "name": "body", "schema": { "type" : "object" } }
        "responses" : {
          "200": {
            "description": "Echo response",
            "schema": { "type": "object" }

See Mojolicious::Plugin::OpenAPI::Guides::Tutorial for a tutorial on how to write a "full" app with application class and controllers.


Mojolicious::Plugin::OpenAPI is Mojolicious::Plugin that add routes and input/output validation to your Mojolicious application based on a OpenAPI (Swagger) specification.

Have a look at the "SEE ALSO" for references to more documentation, or jump right to the tutorial.

Mojolicious::Plugin::OpenAPI will replace Mojolicious::Plugin::Swagger2.



$hash = $c->openapi->spec($json_pointer)
$hash = $c->openapi->spec("/info/title")
$hash = $c->openapi->spec;

Returns the OpenAPI specification. A JSON Pointer can be used to extract a given section of the specification. The default value of $json_pointer will be relative to the current operation. Example:

  "paths": {
    "/pets": {
      "get": {
        // This datastructure is returned by default


$c = $c->openapi->render_spec;

Used to render the specification as either "html" or "json". Set the "stash" in Mojolicious variable "format" to change the format to render.

This helper is called by default, when accessing the "basePath" resource.

The "html" rendering needs improvement. Any help or feedback is much appreciated.


@errors = $c->openapi->validate;

Used to validate a request. @errors holds a list of JSON::Validator::Error objects or empty list on valid input.

Note that this helper is only for customization. You probably want "openapi.valid_input" in most cases.

Validated input parameters will be copied to Mojolicious::Controller/validation, which again can be extracted by the "name" in the parameters list from the spec. Example:

# specification:
"parameters": [{"in": "body", "name": "whatever", "schema": {"type": "object"}}],

# controller
my $body = $c->validation->param("whatever");


$c = $c->openapi->valid_input;

Returns the Mojolicious::Controller object if the input is valid or automatically render an error document if not and return false. See "SYNOPSIS" for example usage.


This plugin register a new handler called openapi. The special thing about this handler is that it will validate the data before sending it back to the user agent. Examples:

$c->render(json => {foo => 123});    # without validation
$c->render(openapi => {foo => 123}); # with validation

This handler will also use "renderer" to format the output data. The code below shows the default "renderer" which generates JSON data:

  OpenAPI => {
    renderer => sub {
      my ($c, $data) = @_;
      return Mojo::JSON::encode_json($data);



$route = $self->route;

The parent Mojolicious::Routes::Route object for all the OpenAPI endpoints.


$jv = $self->validator;

Holds a JSON::Validator::OpenAPI::Mojolicious object.



$self = $self->register($app, \%config);
$self = $app->plugin(OpenAPI => \%config);

Loads the OpenAPI specification, validates it and add routes to $app. It will also set up "HELPERS" and adds a before_render hook for auto-rendering of error documents. The return value is the object instance, which allow you to access the "ATTRIBUTES" after you load the plugin.

%config can have:

  • allow_invalid_ref

    The OpenAPI specification does not allow "$ref" at every level, but setting this flag to a true value will ignore the $ref check.

    Note that setting this attribute is discourage.

  • coerce

    See "coerce" in JSON::Validator for possible values that coerce can take.

    Default: 1

  • default_response

    Used to set the "default" response schema, unless already specified in the spec. Set this argument to undef() if you don't want the default to be added.

    Default value:

      description => "Default response.",
      schema      => {
        type       => "object",
        required   => ["errors"],
        properties => {
          errors => {
            type  => "array",
            items => {
              type       => "object",
              required   => ["message", "path"],
              properties => {message => {"type" => "string"}, path => {"type" => "string"}}

    Note! The default "description" might change.

  • log_level

    log_level is used when logging invalid request/response error messages.

    Default: "warn".

  • renderer

    See "RENDERER".

  • route

    route can be specified in case you want to have a protected API. Example:

    $app->plugin(OpenAPI => {
      route => $app->routes->under("/api")->to("user#auth"),
      url   => $app->home->rel_file("cool.api"),
  • schema

    Can be used to set a different schema, than the default OpenAPI 2.0 spec.

  • spec_route_name

    Name of the route that handles the "basePath" part of the specification and serves the specification. Defaults to "x-mojo-name" in the specification at the top level.

  • url

    See "schema" in JSON::Validator for the different url formats that is accepted.

    spec is an alias for "url", which might make more sense if your specification is written in perl, instead of JSON or YAML.

  • version_from_class

    Can be used to overriden /info/version in the API specification, from the return value from the VERSION() method in version_from_class.

    Defaults to the current $app.


Jan Henning Thorsen


Copyright (C) 2016, Jan Henning Thorsen

This program is free software, you can redistribute it and/or modify it under the terms of the Artistic License version 2.0.