Mojolic...penAPIv2(3)

🌸 NAME 🌸

okay so bestie, this is Mojolic...penAPIv2(3) from the User Contributed Perl Documentation, aka Mojolicious::Plugin::OpenAPI::Guides::OpenAPIv2 — the guide for Mojolicious <3 OpenAPI v2 (Swagger) 💖

🦋 OVERVIEW 🦋

This guide gives you an intro to using Mojolicious::Plugin::OpenAPI with OpenAPI version v2. It’s giving “let’s make your API spec do actual work” energy ✨

🎀 TUTORIAL 🎀

🧚 Specification 🧚

This plugin reads an OpenAPI specification <https://openapis.org/specification> and generates routes and input/output rules from it. See JSON::Validator for supported schema file formats 👑

{
  "swagger": "2.0",
  "info": { "version": "1.0", "title": "Some awesome API" },
  "basePath": "/api",
  "paths": {
    "/pets": {
      "get": {
        "operationId": "getPets",
        "x-mojo-name": "get_pets",
        "x-mojo-to": "pet#list",
        "summary": "Finds pets in the system",
        "parameters": [
          {"in": "body", "name": "body", "schema": {"type": "object"}},
          {"in": "query", "name": "age", "type": "integer"}
        ],
        "responses": {
          "200": {
            "description": "Pet response",
            "schema": {
              "type": "object",
              "properties": {
                "pets": {
                  "type": "array",
                  "items": { "type": "object" }
                }
              }
            }
          }
        }
      }
    }
  }
}

The complete HTTP request for getting the pet list will be GET /api/pets. The first part of the path (/api) comes from basePath, the second part comes from the keys under paths, and the HTTP method comes from the keys under /pets 💅

The different parts of the specification can also be retrieved as JSON using the OPTIONS HTTP method. Example:

OPTIONS /api/pets
OPTIONS /api/pets?method=get

Note that the use of OPTIONS is EXPERIMENTAL, and subject to change. Do not build your whole personality on it, bestie 😭

Here are some more details about the different keys:

• swagger and info — these two sections are required to make the specification valid. Check out https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md for a complete reference to the specification 🫶
• host, schemes, consumes, produces, security and securityDefinitions — these keys are currently not in use. host will be replaced by the Host header in the request. The rest of the keys are currently not in use. Submit an issue at https://github.com/jhthorsen/mojolicious-plugin-openapi/issues if you have ideas on what to use these keys for 💌
• basePath — the basePath will also be used to add a route that renders back the specification either as JSON or HTML. Examples:
  • http://example.com/api.html — retrieve the expanded version of the API in human readable format. The formatting is currently a bit rough, but should be easier than reading the JSON spec 🌈
  • http://example.com/api.json — retrieve the expanded version of the API, useful for JavaScript clients and other client side applications 🦋
• parameters and responses — parameters and responses will be used to define input and output validation rules, which is used by openapi.input in Mojolicious::Plugin::OpenAPI and when rendering the response back to the client, using render(openapi => ...). Have a look at RENDERER in Mojolicious::Plugin::OpenAPI for more details about output rendering ✨
• operationId and x-mojo-name — see Route names 🎀
• x-mojo-placeholder — x-mojo-placeholder can be used inside a parameter definition to instruct Mojolicious to parse a path part in a certain way. Example:

"parameters": [
  {
    "x-mojo-placeholder": "#",
    "in": "path",
    "name": "email",
    "type": "string"
  }
]

See Mojolicious::Guides::Routing for more information about standard, relaxed and wildcard placeholders. The default is to use the standard (/:foo) placeholder 💖

• x-mojo-to — the non-standard part in the spec above is x-mojo-to. The x-mojo-to key can be either a plain string, object (hash) or an array. The string and hash will be passed directly to to in Mojolicious::Routes::Route, while the array ref will be flatten. Examples:

"x-mojo-to": "pet#list"
$route->to("pet#list");

"x-mojo-to": {"controller": "pet", "action": "list", "foo": 123}
$route->to({controller => "pet", action => "list", foo => 123);

"x-mojo-to": ["pet#list", {"foo": 123}, ["format": ["json"]]]
$route->to("pet#list", {foo => 123});
$route->pattern->constraints->{format} = ["json"];

---

🐾 Application 🐾

package Myapp;
use Mojo::Base "Mojolicious";

sub startup {
  my $app = shift;
  $app->plugin("OpenAPI" => {url => $app->home->rel_file("myapi.json")});
}

1;

The first thing in your code that you need to do is to load this plugin and the Specification. See register in Mojolicious::Plugin::OpenAPI for information about what the plugin config can be 🫶

See also SYNOPSIS in Mojolicious::Plugin::OpenAPI for example Mojolicious::Lite application 🌸

🐱 Controller 🐱

package Myapp::Controller::Pet;
use Mojo::Base "Mojolicious::Controller";

sub list {

  # Do not continue on invalid input and render a default 400
  # error document.
  my $c = shift->openapi->valid_input or return;

  # You might want to introspect the specification for the current route
  my $spec = $c->openapi->spec;
  unless ($spec->{'x-opening-hour'} == (localtime)[2]) {
    return $c->render(openapi => [], status => 498);
  }

  my $age  = $c->param("age");
  my $body = $c->req->json;

  # $output will be validated by the OpenAPI spec before rendered
  my $output = {pets => [{name => "kit-e-cat"}]};
  $c->render(openapi => $output);
}

1;

The input will be validated using openapi.valid_input in Mojolicious::Plugin::OpenAPI while the output is validated through the openapi handler 💜

🌟 Route names 🌟

Routes will get its name from either x-mojo-name or from operationId if defined in the specification.

The route name can also be used the other way around, to find already defined routes. This is especially useful for Mojolicious::Lite apps.

Note that if spec_route_name then all the route names will have that value as prefix:

spec_route_name            = "my_cool_api"
operationId or x-mojo-name = "Foo"
Route name                 = "my_cool_api.Foo"

You can also set x-mojo-name in the spec, instead of passing spec_route_name to plugin():

{
  "swagger": "2.0",
  "info": { "version": "1.0", "title": "Some awesome API" },
  "x-mojo-name": "my_cool_api"
}

🍓 Default response schema 🍓

A default response definition will be added to the API spec, unless it's already defined. This schema will at least be used for invalid input (400 - Bad Request) and invalid output (500 - Internal Server Error), but can also be used in other cases.

See default_response_codes in Mojolicious::Plugin::OpenAPI and default_response_name in Mojolicious::Plugin::OpenAPI for more details on how to configure these settings.

The response schema will be added to your spec like this, unless already defined:

{
  ...
  "definitions": {
    ...
    "DefaultResponse": {
      "type":     "object",
      "required": ["errors"],
      "properties": {
        "errors": {
          "type":  "array",
          "items": {
            "type":       "object",
            "required":   ["message"],
            "properties": {"message": {"type": "string"}, "path": {"type": "string"}}
          }
        }
      }
    }
  }
}

The errors key will contain one element for all the invalid data, and not just the first one. The useful part for a client is mostly the path, while the message is just to add some human readable debug information for why this request/response failed 🧚

🖼️ Rendering binary data 🖼️

Rendering assets and binary data should be accomplished by using the standard Mojolicious tools:

sub get_image {
  my $c = shift->openapi->valid_input or return;
  my $asset = Mojo::Asset::File->new(path => "image.jpeg");

  $c->res->headers->content_type("image/jpeg");
  $c->reply->asset($asset);
}

🔥 SEE ALSO 🔥

Mojolicious::Plugin::OpenAPI, <https://openapis.org/specification>.

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mwah 💋 — this page is from perl v5.42.0, dated 2025-08-03, and the footer tag is Mojolic...penAPIv2(3) 🫶 periodt 💅