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Mojolicious-Plugin-OpenAPI-5.09
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/ Mojolicious::Plugin::OpenAPI::Guides::OpenAPIv3

NAME

Mojolicious::Plugin::OpenAPI::Guides::OpenAPIv3 - Mojolicious <3 OpenAPI v3

OVERVIEW

This guide will give you an introduction on how to use Mojolicious::Plugin::OpenAPI with OpenAPI version v3.x.

TUTORIAL

Specification

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

{
  "openapi": "3.0.2",
  "info": {
    "version": "1.0",
    "title": "Some awesome API"
  },
  "paths": {
    "/pets": {
      "get": {
        "operationId": "getPets",
        "x-mojo-name": "get_pets",
        "x-mojo-to": "pet#list",
        "summary": "Finds pets in the system",
        "parameters": [
          {
            "in": "query",
            "name": "age",
            "schema": {
              "type": "integer"
            }
          }
        ],
        "requestBody": {
          "content": {
            "application/json": {
              "schema": {
                "type": "object"
              }
            }
          }
        },
        "responses": {
          "200": {
            "description": "Pet response",
            "content": {
              "application/json": {
                "schema": {
                  "type": "object",
                  "properties": {
                    "pets": {
                      "type": "array",
                      "items": {
                        "type": "object"
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  },
  "servers": [
    {
      "url": "/api"
    }
  ]
}

The complete HTTP request for getting the "pet list" will be GET /api/pets The first part of the path ("/api") comes from servers, 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.

Here are some more details about the different keys:

  • openapi, info and paths

    These three sections are required to make the specification valid. Check out https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md for a complete reference to the specification.

  • parameters, requestBody and responses

    parameters, requestBody 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 => ...).

    Here OpenAPIv3 input differs from the v2 spec, where parameters is used for input in the path or query of the request. The requestBody is used for input passed in the body.

    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 flattened. 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"];

  • security and securitySchemes

    The securityScheme is added under components, where one way is to have the client place an apiKey in the header of the request

    {
  ...
  "components": {
    "securitySchemes": {
      "apiKey": {
        "name": "X-Api-Key",
        "in": "header",
        "type": "apiKey"
      }
    }
  }
}

    It is then referenced under the path object as security like this

    {
  ...
  "paths": {
    "/pets": {
      "get": {
        "operationId": "getPets",
        ...
        "security": [
          {
            "apiKey": []
          }
        ]
      }
    }
  }
}

    You can then utilize security, by adding a security callback when loading the plugin

    $self->plugin(
  OpenAPI => {
    spec     => $self->static->file("openapi.json")->path,
    security => {
      apiKey => sub {
        my ($c, $definition, $scopes, $cb) = @_;
        if (my $key = $c->tx->req->content->headers->header('X-Api-Key')) {
          if (got_valid_api_key()) {
            return $c->$cb();
          }
          else {
            return $c->$cb('Api Key not valid');
          }
        }
        else {
          return $c->$cb('Api Key header not present');
        }
      }
    }
  }
);

References with files

Only a file reference like

"$ref": "my-other-cool-component.json#/components/schemas/inputSchema"

Is supported, though a valid path must be used for both the reference and in the referenced file, in order to produce a valid spec output.

See "File references" in Known Issues for unsupported file references

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 then 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 is used 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():

{
  "openapi": "3.0.2",
  "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:

{
  ...
  "components": {
    ...
    "schemas": {
      ...
      "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);
}

OpenAPIv2 to OpenAPIv3 conversion

Both online and offline tools are available. One example is of this is https://github.com/mermade/openapi-webconverter

Known issues

File references

Relative file references like the following

"$ref": "my-cool-component.json#"
"$ref": "my-cool-component.json"

Will also be placed under '#/definitions/...', again producing a spec output which will not pass validation.

SEE ALSO

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