openapify 0.7
Framework agnostic OpenAPI Specification generation for code lovers
License: Apache License, Version 2.0
Requires Python: >=3.8

# openapify

###### Framework agnostic OpenAPI Specification generation for code lovers

[![Build Status](https://github.com/Fatal1ty/openapify/workflows/tests/badge.svg)](https://github.com/Fatal1ty/openapify/actions)
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[![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)

---

This library is designed for code-first people who don't want to bother diving
into the details
of [OpenAPI Specification](https://spec.openapis.org/oas/v3.1.0), but who
instead want to use advantages of Python typing system, IDE code-completion and
static type checkers to continuously build the API documentation and keep it
always up to date.

Openapify is based on the idea of applying decorators on route handlers. Any
web-framework has a routing system that let us link a route to a handler
(a high-level function or a class method). By using decorators, we can add
information about requests, responses and other details that will then be used
to create an entire OpenAPI document.

> [!WARNING]\
> This library is currently in pre-release stage and may have backward
> incompatible changes prior to version 1.0. Please use caution when using this
> library in production environments and be sure to thoroughly test any updates
> before upgrading to a new version.

Table of contents
--------------------------------------------------------------------------------

* [Installation](#installation)
* [Quickstart](#quickstart)
* [Building the OpenAPI Document](#building-the-openapi-document)
* [Integration with web-frameworks](#integration-with-web-frameworks)
    * [aiohttp](#aiohttp)
    * [Writing your own integration](#writing-your-own-integration)
* [Decorators](#decorators)
    * [Generic operation info](#generic-operation-info)
    * [Request](#request)
    * [Response](#response)
    * [Security requirements](#security-requirements)
* [Plugins](#plugins)
  * [`schema_helper`](#schema_helper)
  * [`media_type_helper`](#media_type_helper)

Installation
--------------------------------------------------------------------------------

Use pip to install:

```shell
$ pip install openapify
```

Quickstart
--------------------------------------------------------------------------------

> [!NOTE]\
> In the following example, we will intentionally demonstrate the process of
> creating an OpenAPI document without being tied to a specific web-framework.
> However, this process may be easier on a supported web-framework.
> See [Integration with web-frameworks](#integration-with-web-frameworks) for
> more info.

Let's see how to build an OpenAPI document with openapify. Suppose we are
writing an app for a bookstore that return a list of new books. Here we have a
dataclass model `Book` that would be used as a response model in a real-life
scenario. A function `get_new_books` is our handler.

```python
from dataclasses import dataclass

@dataclass
class Book:
    title: str
    author: str
    year: int

def get_new_books(...):
    ...
```

Now we want to say that our handler returns a json serialized list of books
limited by the optional `count` parameter. We use `request_schema`
and `response_schema` decorators accordingly:

```python
from openapify import request_schema, response_schema

@request_schema(query_params={"count": int})
@response_schema(list[Book])
def get_new_books(...):
    ...
```

And now we need to collect all the route definitions and pass them to the
`build_spec` function. This function returns an object that has `to_yaml`
method.

```python
from openapify import build_spec
from openapify.core.models import RouteDef

routes = [RouteDef("/books", "get", get_new_books)]
spec = build_spec(routes)
print(spec.to_yaml())
```

As a result, we will get the following OpenAPI document which can be rendered
using tools such as Swagger UI:

```yaml
openapi: 3.1.0
info:
  title: API
  version: 1.0.0
paths:
  /books:
    get:
      parameters:
      - name: count
        in: query
        schema:
          type: integer
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Book'
components:
  schemas:
    Book:
      type: object
      title: Book
      properties:
        title:
          type: string
        author:
          type: string
        year:
          type: integer
      additionalProperties: false
      required:
      - title
      - author
      - year
```

Building the OpenAPI Document
--------------------------------------------------------------------------------
The final goal of this library is to build
the [OpenAPI Document](https://spec.openapis.org/oas/v3.1.0#openapi-document)
for your web-application. This document consists of common information about
the application, such as a title and version, and specific information that
outlines the functionalities of the API.

Since openapify is now based
on [apispec](https://github.com/marshmallow-code/apispec) library, the OpenAPI
document is presented by `APISpec` class for the convenience of using the
existing ecosystem of plugins. However, openapify has its own
subclass `OpenAPIDocument` which makes it easier to add some common fields,
such as an array
of [Server](https://spec.openapis.org/oas/v3.1.0#server-object) objects or
array of
common [Security Scheme](https://spec.openapis.org/oas/v3.1.0#security-scheme-object)
objects.

To build the document, there is `build_spec` function. The very basic document
can be created by calling it with an empty list of route definitions, leaving
all the parameters with their default values.
```python
from openapify import build_spec

print(build_spec([]).to_yaml())
```

As a result, we will get the following document:

```yaml
openapi: 3.1.0
info:
  title: API
  version: 1.0.0
paths: {}
```

We can change the common document attributes either by passing them
to `build_spec`:

```python
from openapify import build_spec
from openapify.core.openapi.models import HTTPSecurityScheme

build_spec(
    routes=[],
    title="My Bookstore API",
    version="1.1.0",
    openapi_version="3.1.0",
    servers=["http://127.0.0.1"],
    security_schemes={"basic_auth": HTTPSecurityScheme()}
)
```

or using a prepared `OpenAPIDocument` object:

```python
from openapify import OpenAPIDocument, build_spec
from openapify.core.openapi.models import HTTPSecurityScheme

spec = OpenAPIDocument(
    title="My Bookstore API",
    version="1.1.0",
    openapi_version="3.1.0",
    servers=["http://127.0.0.1"],
    security_schemes={"basic_auth": HTTPSecurityScheme()},
)
build_spec([], spec)
```

To add meaning to our document, we can
add [Path](https://spec.openapis.org/oas/v3.1.0#paths-object),
[Component](https://spec.openapis.org/oas/v3.1.0#components-object)
and other OpenAPI objects by applying [decorators](#decorators) on our route
handlers and constructing route definitions that will be passed to the builder.
A single complete route definition presented by `RouteDef` class can look like
this:

```python
from openapify.core.models import RouteDef
from openapify.core.openapi.models import Parameter, ParameterLocation

def get_book_by_id_handler(...):
    ...

RouteDef(
    path="/book/{id}",
    method="get",
    handler=get_book_by_id_handler,
    summary="Getting the book",
    description="Getting the book by id",
    parameters=[
        Parameter(
            name="id",
            location=ParameterLocation.PATH,
            required=True,
            schema={"type": "integer"},
        )
    ],
    tags=["book"],
)
```

As will be shown further, optional
arguments `summary`, `description`, `parameters` and `tags` can be overridden
or extended by `operation_docs` and `request_schema` decorators.

The creating of these route definitions can be automated and adapted to a
specific web-framework, and openapify has built-in support for a few of them.
See [Integration with web-frameworks](#integration-with-web-frameworks) for
details.

Integration with web-frameworks
--------------------------------------------------------------------------------

There is built-in support for a few web-frameworks, which makes creating the
documentation even easier and more fun. Any other frameworks can be integrated
with a little effort. If you are ready to take on this, you are very welcome to
create a [pull request](https://github.com/Fatal1ty/openapify/pulls).

### aiohttp

The documentation for [aiohttp](https://github.com/aio-libs/aiohttp)
web-application can be built in three ways:

* Using an already existing [`aiohttp.web.Application`](https://docs.aiohttp.org/en/stable/web_reference.html#application) object
* Using a set of [`aiohttp.web.RouteDef`](https://docs.aiohttp.org/en/stable/web_reference.html#aiohttp.web.RouteDef) objects
* Using a set of objects implementing [`AioHttpRouteDef`](https://github.com/Fatal1ty/openapify/blob/2bbf2e99c06b31fa2f1465f2ebc118884ce2bb95/openapify/ext/web/aiohttp.py#L43-L46) protocol

All we need is to pass either an application, or a set of route defs to
modified `build_spec` function. See the example:
```python
from aiohttp import web
from openapify import request_schema, response_schema
from openapify.ext.web.aiohttp import build_spec

routes = web.RouteTableDef()

@response_schema(str, media_type="text/plain")
@routes.post("/")
async def hello(request):
    return web.Response(text="Hello, world")

app = web.Application()
app.add_routes(routes)

print(build_spec(app).to_yaml())
```
As a result, we will get the following document:

```yaml
openapi: 3.1.0
info:
  title: API
  version: 1.0.0
paths:
  /:
    post:
      responses:
        '200':
          description: OK
          content:
            text/plain:
              schema:
                type: string
```

### Writing your own integration

🚧 To be described

Decorators
--------------------------------------------------------------------------------

Openapify has several decorators that embed necessary specific information for
later use when building the OpenAPI document. In general, decorators will
define the information that will be included in
the [Operation Object](https://spec.openapis.org/oas/v3.1.0#operation-object)
which describes a single API operation on a path. We will look at what each
decorator parameter is responsible for and how it is reflected in the final
document.

### Generic operation info

Decorator `operation_docs` adds generic information about the Operation object,
which includes summary, description, tags, external documentation and
deprecation marker.

```python
from openapify import operation_docs
```

#### summary

An optional, string summary, intended to apply to the operation. This affects
the value of
the [`summary`](https://spec.openapis.org/oas/v3.1.0#operation-object) field of
the Operation object.

| Possible types | Examples              |
|----------------|-----------------------|
| `str`          | `"Getting new books"` |

#### description

An optional, string description, intended to apply to the
operation. [CommonMark syntax](https://spec.commonmark.org) MAY be used for
rich text representation. This affects the value of
the [`description`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object.

| Possible types | Examples                    |
|----------------|-----------------------------|
| `str`          | `"Returns a list of books"` |

#### tags

A list of tags for API documentation control. Tags can be used for logical
grouping of operations by resources or any other qualifier. This affects the
value of the [`tags`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object.

| Possible types  | Examples   |
|-----------------|------------|
| `Sequence[str]` | `["book"]` |

#### operation_id

Unique string used to identify the operation. This affects the
value of
the [`operationId`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object.

| Possible types | Examples   |
|----------------|------------|
| `str`          | `getBooks` |

#### external_docs

Additional external documentation for the operation. It can be a single url or
(url, description) pair. This affects the value of
the [`summary`](https://spec.openapis.org/oas/v3.1.0#operation-object) field of
the Operation object.

| Possible types    | Examples                                                                  |
|-------------------|---------------------------------------------------------------------------|
| `str`             | `"https://example.org/docs/books"`                                        |
| `Tuple[str, str]` | `("https://example.org/docs/books", "External documentation for /books")` |

#### deprecated

Declares the operation to be deprecated. Consumers SHOULD refrain from usage
of the declared operation. Default value is false. This affects the value of
the [`deprecated`](https://spec.openapis.org/oas/v3.1.0#operation-object) field
of the Operation object.

| Possible types | Examples                       |
|----------------|--------------------------------|
| `bool`         | <code lang="python">True</pre> |

### Request

Decorator `request_schema` adds information about the operation requests.
Request can have a body, query parameters, headers and cookies.

```python
from openapify import request_schema
```

#### body

A request body can be described entirely by one `body` parameter of type `Body`
or partially by separate `body_*` parameters (see below).

In the first case it is `openapify.core.models.Body` object that has all the
separate `body_*` parameters inside. This affects the value of
the [`requestBody`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object.

In the second case it is the request body Python data type for which the JSON
Schema will be built. This affects the value of
the [`requestBody`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`schema`](https://spec.openapis.org/oas/v3.1.0#media-type-object) field of
Media Type object inside
the value
of [`content`](https://spec.openapis.org/oas/v3.1.0#request-body-object) field
of Request Body object.

<table>
<tr>
<th>Possible types</th>
<th>Examples</th>
</tr>
<tr>
<td> <code>Type</code> </td>
<td>

```python
Book
```

</td>
</tr>
<tr>
<td> <code>Body</code> </td>
<td>

```python
Body(
    value_type=Book,
    media_type="application/json",
    required=True,
    description="A book",
    example={
        "title": "Anna Karenina",
        "author": "Leo Tolstoy",
        "year": 1877,
    },
)
```

</td>
</tr>
</table>

#### media_type

A media type
or [media type range](https://www.rfc-editor.org/rfc/rfc7231#appendix-D) of the
request body. This affects the value of
the [`requestBody`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the key
of [`content`](https://spec.openapis.org/oas/v3.1.0#request-body-object) field
of Request Body object.

The default value is `"application/json"`.

| Possible types | Examples            |
|----------------|---------------------|
| `str`          | `"application/xml"` |

#### body_required

Determines if the request body is required in the request. Defaults to false.
This affects the value of
the [`requestBody`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`required`](https://spec.openapis.org/oas/v3.1.0#request-body-object)
field of Request Body object.

| Possible types | Examples |
|----------------|----------|
| `bool`         | `True`   |

#### body_description

A brief description of the request body. This could contain examples of
use. [CommonMark syntax](https://spec.commonmark.org) MAY be used for rich text
representation. This affects the value of
the [`requestBody`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`description`](https://spec.openapis.org/oas/v3.1.0#request-body-object)
field of Request Body object.

| Possible types | Examples   |
|----------------|------------|
| `str`          | `"A book"` |

#### body_example

Example of the request body. The example object SHOULD be in the correct format
as specified by the media type. This affects the value of
the [`requestBody`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`example`](https://spec.openapis.org/oas/v3.1.0#media-type-object) field
of
Media Type object inside
the value
of [`content`](https://spec.openapis.org/oas/v3.1.0#request-body-object) field
of Request Body object.

<table>
<tr>
<th>Possible types</th>
<th>Examples</th>
</tr>
<tr>
<td> <code>Any</code> </td>
<td>

```python
{
    "title": "Anna Karenina",
    "author": "Leo Tolstoy",
    "year": 1877,
}
```

</td>
</tr>
</table>

#### body_examples

Examples of the request body. Each example object SHOULD match the media type
and specified schema if present. This affects the value of
the [`requestBody`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`examples`](https://spec.openapis.org/oas/v3.1.0#media-type-object) field
of
Media Type object inside
the value
of [`content`](https://spec.openapis.org/oas/v3.1.0#request-body-object) field
of Request Body object.

The values of this dictionary could be either examples themselves,
or `openapify.core.openapi.models.Example` objects. In the latter case,
extended information about examples, such as a summary and description, can be
added to the [Example](https://spec.openapis.org/oas/v3.1.0#example-object)
object.

<table>
<tr>
<th>Possible types</th>
<th>Examples</th>
</tr>
<tr>
<td> <code>Mapping[str, Any]</code> </td>
<td>

```python
{
    "Anna Karenina": {
        "title": "Anna Karenina",
        "author": "Leo Tolstoy",
        "year": 1877,
    }
}
```

</td>
</tr>
<tr>
<td> <code>Mapping[str, Example]</code> </td>
<td>

```python
{
    "Anna Karenina": Example(
        value={
            "title": "Anna Karenina",
            "author": "Leo Tolstoy",
            "year": 1877,
        },
        summary="The book 'Anna Karenina'",
    )
}
```

</td>
</tr>
</table>

#### query_params

Dictionary of query parameters applicable for the operation, where the key is
the parameter name and the value can be either a Python data type or
a `QueryParam` object.

In the first case it is the Python data type for the query parameter for which
the JSON Schema will be built. This affects the value of
the [`parameters`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`schema`](https://spec.openapis.org/oas/v3.1.0#parameter-object) field of
Parameter object.

In the second case it is `openapify.core.models.QueryParam` object that can
have extended information about the parameter, such as a default value,
deprecation marker, examples etc.

<table>
<tr>
<th>Possible types</th>
<th>Examples</th>
</tr>
<tr>
<td> <code>Mapping[str, Type]</code> </td>
<td>

```python
{"count": int}
```

</td>
</tr>
<tr>
<td> <code>Mapping[str, QueryParam]</code> </td>
<td>

```python
{
    "count": QueryParam(
        value_type=int,
        default=10,
        required=True,
        description="Limits the number of books returned",
        deprecated=False,
        allowEmptyValue=False,
        example=42,
    )
}
```

</td>
</tr>
</table>

### path_params

Dictionary of path parameters applicable for the operation, where the key is
the parameter name and the value can be either a Python data type or
a `PathParam` object.

In the first case it is the Python data type for the path parameter for which
the JSON Schema will be built. This affects the value of
the [`parameters`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`schema`](https://spec.openapis.org/oas/v3.1.0#parameter-object) field of
Parameter object.

In the second case it is `openapify.core.models.PathParam` object that can
have extended information about the parameter, such as a description, examples.

<table>
<tr>
<th>Possible types</th>
<th>Examples</th>
</tr>
<tr>
<td> <code>Mapping[str, Type]</code> </td>
<td>

```python
{"id": UUID}
```

</td>
</tr>
<tr>
<td> <code>Mapping[str, PathParam]</code> </td>
<td>

```python
{
    "id": PathParam(
        value_type=UUID,
        description="ID of the book",
        example="eab9d66d-4317-464a-a995-510bd6e2148f",
    )
}
```

</td>
</tr>
</table>

#### headers

Dictionary of request headers applicable for the operation, where the key is
the header name and the value can be either a string or a `Header` object.

In the first case it is the header description. This affects the value of
the [`parameters`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`description`](https://spec.openapis.org/oas/v3.1.0#parameter-object)
field of Parameter object.

In the second case it is `openapify.core.models.Header` object that can have
extended information about the header, such as a description, deprecation
marker, examples etc.

<table>
<tr>
<th>Possible types</th>
<th>Examples</th>
</tr>
<tr>
<td> <code>Mapping[str, str]</code> </td>
<td>

```python
{"X-Requested-With": "Information about the creation of the request"}
```

</td>
</tr>
<tr>
<td> <code>Mapping[str, Header]</code> </td>
<td>

```python
{
    "X-Requested-With": Header(
        description="Information about the creation of the request",
        required=True,
        value_type=str,
        deprecated=False,
        allowEmptyValue=False,
        example="XMLHttpRequest",
    )
}
```

</td>
</tr>
</table>

#### cookies

Dictionary of request cookies applicable for the operation, where the key is
the cookie name and the value can be either a string or a `Cookie` object.

In the first case it is the cookie description. This affects the value of
the [`parameters`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`description`](https://spec.openapis.org/oas/v3.1.0#parameter-object)
field of Parameter object.

In the second case it is `openapify.core.models.Cookie` object that can have
extended information about the cookie, such as a description, deprecation
marker, examples etc.

<table>
<tr>
<th>Possible types</th>
<th>Examples</th>
</tr>
<tr>
<td> <code>Mapping[str, str]</code> </td>
<td>

```python
{"__ga": "A randomly generated number as a client ID"}
```

</td>
</tr>
<tr>
<td> <code>Mapping[str, Cookie]</code> </td>
<td>

```python
{
    "__ga": Cookie(
        description="A randomly generated number as a client ID",
        required=True,
        value_type=str,
        deprecated=False,
        allowEmptyValue=False,
        example="1.2.345678901.2345678901",
    )
}
```

</td>
</tr>
</table>

### Response

Decorator `response_schema` describes a single response from the API Operation.
Response can have an HTTP code, body and headers. If the Operation supports
more than one response, then the decorator must be applied multiple times to
cover each of them.

```python
from openapify import response_schema
```

#### body

A Python data type for the response body for which
the JSON Schema will be built. This affects the value of
the [`responses`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`schema`](https://spec.openapis.org/oas/v3.1.0#media-type-object) field of
Media Type object inside the value
of [`content`](https://spec.openapis.org/oas/v3.1.0#response-object) field
of Response object.

| Possible types | Examples |
|----------------|----------|
| `Type`         | `Book`   |

#### http_code

An HTTP code of the response. This affects the value of
the [`responses`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely, the patterned key in
the [Responses](https://spec.openapis.org/oas/v3.1.0#responses-object) object.

| Possible types | Examples |
|----------------|----------|
| `str`          | `"200"`  |
| `int`          | `400`    |

#### media_type

A media type
or [media type range](https://www.rfc-editor.org/rfc/rfc7231#appendix-D) of the
response body. This affects the value of
the [`responses`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely, the key
of [`content`](https://spec.openapis.org/oas/v3.1.0#response-object) field of
Response object.

The default value is `"application/json"`.

| Possible types | Examples            |
|----------------|---------------------|
| `str`          | `"application/xml"` |

####

#### description

A description of the response. [CommonMark syntax](https://spec.commonmark.org)
MAY be used for rich text representation. This affects the value of
the [`responses`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`description`](https://spec.openapis.org/oas/v3.1.0#response-object) field
of Response object.


| Possible types | Examples                |
|----------------|-------------------------|
| `str`          | `"Invalid ID Supplied"` |

#### headers

Dictionary of response headers applicable for the operation, where the key is
the header name and the value can be either a string or a `Header` object.

In the first case it is the header description. This affects the value of
the [`responses`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`description`](https://spec.openapis.org/oas/v3.1.0#header-object)
field of Header object.

In the second case it is `openapify.core.models.Header` object that can have
extended information about the header, such as a description, deprecation
marker, examples etc.

<table>
<tr>
<th>Possible types</th>
<th>Examples</th>
</tr>
<tr>
<td> <code>Mapping[str, str]</code> </td>
<td>

```python
{"Content-Location": "An alternate location for the returned data"}
```

</td>
</tr>
<tr>
<td> <code>Mapping[str, Header]</code> </td>
<td>

```python
{
    "Content-Location": Header(
        description="An alternate location for the returned data",
        example="/index.htm",
    )
}
```

</td>
</tr>
</table>

#### example

Example of the response body. The example object SHOULD be in the correct format
as specified by the media type. This affects the value of
the [`responses`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`example`](https://spec.openapis.org/oas/v3.1.0#media-type-object) field
of Media Type object inside the value
of [`content`](https://spec.openapis.org/oas/v3.1.0#response-object) field of
Response object.

<table>
<tr>
<th>Possible types</th>
<th>Examples</th>
</tr>
<tr>
<td> <code>Any</code> </td>
<td>

```python
{
    "title": "Anna Karenina",
    "author": "Leo Tolstoy",
    "year": 1877,
}
```

</td>
</tr>
</table>

#### examples

Examples of the response body. Each example object SHOULD match the media type
and specified schema if present. This affects the value of
the [`responses`](https://spec.openapis.org/oas/v3.1.0#operation-object)
field of the Operation object, or more precisely,
the [`examples`](https://spec.openapis.org/oas/v3.1.0#media-type-object) field
of Media Type object inside the value
of [`content`](https://spec.openapis.org/oas/v3.1.0#response-object) field of
Response object.

The values of this dictionary could be either examples themselves,
or `openapify.core.openapi.models.Example` objects. In the latter case,
extended information about examples, such as a summary and description, can be
added to the [Example](https://spec.openapis.org/oas/v3.1.0#example-object)
object.

<table>
<tr>
<th>Possible types</th>
<th>Examples</th>
</tr>
<tr>
<td> <code>Mapping[str, Any]</code> </td>
<td>

```python
{
    "Anna Karenina": {
        "title": "Anna Karenina",
        "author": "Leo Tolstoy",
        "year": 1877,
    }
}
```

</td>
</tr>
<tr>
<td> <code>Mapping[str, Example]</code> </td>
<td>

```python
{
    "Anna Karenina": Example(
        value={
            "title": "Anna Karenina",
            "author": "Leo Tolstoy",
            "year": 1877,
        },
        summary="The book 'Anna Karenina'",
    )
}
```

</td>
</tr>
</table>

### Security requirements

Decorator `security_requirements`
declares [security mechanisms](https://spec.openapis.org/oas/v3.1.0#securityRequirementObject)
that can be used for the operation.

```python
from openapify import security_requirements
```

This decorator takes one or more `SecurityRequirement` mappings, where the key
is the requirement name and the value is `SecurityScheme` object. There are
classes for
each [security scheme](https://spec.openapis.org/oas/v3.1.0#security-scheme-object)
which can be imported as follows:

```python
from openapify.core.openapi.models import (
    APIKeySecurityScheme,
    HTTPSecurityScheme,
    OAuth2SecurityScheme,
    OpenIDConnectSecurityScheme,
)
```

For example, to add authorization by token, you can write something like this:

```python
from openapify import security_requirements
from openapify.core.openapi.models import (
    APIKeySecurityScheme,
    SecuritySchemeAPIKeyLocation,
)

XAuthTokenSecurityRequirement = {
    "x-auth-token": APIKeySecurityScheme(
        name="X-Auh-Token",
        location=SecuritySchemeAPIKeyLocation.HEADER,
    )
}

@security_requirements(XAuthTokenSecurityRequirement)
def secure_operation():
    ...
```

And the generated specification document will look like this:

```yaml
openapi: 3.1.0
info:
  title: API
  version: 1.0.0
paths:
  /secure_path:
    get:
      security:
      - x-auth-token: []
components:
  securitySchemes:
    x-auth-token:
      type: apiKey
      name: X-Auh-Token
      in: header
```

Plugins
--------------------------------------------------------------------------------

Some aspects of creating an OpenAPI document can be changed using plugins.
There is `openapify.plugins.BasePlugin` base class, which has all the methods
available for definition. If you want to write a plugin that, for example, will
only generate schema for request parameters, then it will be enough for you to
define only one appropriate method, and leave the rest non-implemented.
Plugin system works by going through all registered plugins and calling
the appropriate method. If such a method raises `NotImplementedError` or
returns `None`, it is assumed that this plugin doesn't provide the necessary
functionality. Iteration stops at the first plugin that returned something
other than `None`.

Plugins are registered via the `plugins` argument of the `build_spec` function:

```python
from openapify import BasePlugin, build_spec


class MyPlugin1(BasePlugin):
    def schema_helper(...):
        # return something meaningful here, see the following chapters
        ...


build_spec(..., plugins=[MyPlugin1()])
```

### `schema_helper`

OpenAPI [Schema](https://spec.openapis.org/oas/v3.1.0#schemaObject) object
is built from python types stored in the `value_type` attribute of the
following openapify dataclasses defined in `openapify.core.models`:
* `Body`
* `Cookie`
* `Header`
* `QueryParam`

Out of the box, the schema is generated by using
[`mashumaro`](https://github.com/Fatal1ty/mashumaro) library (see the note
below), but support for third-party entity schema generators can be achieved
through `schema_helper` method. For example, here's what a plugin for pydantic
models might look like:

```python
from typing import Any

from openapify import BasePlugin
from openapify.core.models import Body, Cookie, Header, QueryParam
from pydantic import BaseModel


class PydanticSchemaPlugin(BasePlugin):
    def schema_helper(
        self,
        obj: Body | Cookie | Header | QueryParam,
        name: str | None = None,
    ) -> dict[str, Any] | None:
        if issubclass(obj.value_type, BaseModel):
            schema = obj.value_type.model_json_schema(
                ref_template="#/components/schemas/{model}"
            )
            self.spec.components.schemas.update(schema.pop("$defs", {}))
            return schema
```

> [!NOTE]\
> The [`BaseSchemaPlugin`](https://github.com/Fatal1ty/openapify/blob/master/openapify/core/base_plugins.py#L41-L64),
> which is enabled by default and has the lowest priority, is responsible for
> generating the schema. This plugin utilizes the mashumaro library for schema
> generation, which in turn incorporates its own [plugin system](https://github.com/Fatal1ty/mashumaro?tab=readme-ov-file#json-schema-plugins),
> enabling customization of JSON Schema generation and support for additional
> data types. For more nuanced modifications, particularly within nested data
> models, you can employ `BaseSchemaPlugin` with a specified list of mashumaro JSON
> Schema plugins. This approach allows for finer control over schema generation
> when needed:
> ```python
> from mashumaro.jsonschema.plugins import DocstringDescriptionPlugin
>
> from openapify import build_spec
> from openapify.core.base_plugins import BaseSchemaPlugin
>
> spec = build_spec(
>     routes=[...],
>     plugins=[
>         BaseSchemaPlugin(
>             plugins=[
>                 DocstringDescriptionPlugin(),
>             ]
>         ),
>     ],
> )
> ```

### media_type_helper

A media type is used in OpenAPI Request
[Body](https://spec.openapis.org/oas/v3.1.0#request-body-object) and
[Response](https://spec.openapis.org/oas/v3.1.0#response-object) objects.
By default, `application/octet-stream` is applied for `bytes` or `bytearray`
types, and `application/json` is applied otherwise. You can support more media
types or override existing ones with `media_type_helper` method.

Let's imagine that you have an API route that returns PNG images as the body.
You can have a separate model class representing images, but the more common
case is to use `typing.Annotated` wrapper for bytes. Here's what a plugin for
`image/png` media type might look like:

```python
from typing import Annotated, Any, Dict, Optional

from openapify import BasePlugin, build_spec, response_schema
from openapify.core.models import Body, RouteDef

ImagePNG = Annotated[bytes, "PNG"]


class ImagePNGPlugin(BasePlugin):
    def media_type_helper(
        self, body: Body, schema: Dict[str, Any]
    ) -> Optional[str]:
        if body.value_type is ImagePNG:
            return "image/png"


@response_schema(body=ImagePNG)
def foo():
    ...


routes = [RouteDef("/foo", "get", foo)]
spec = build_spec(routes, plugins=[ImagePNGPlugin()])
print(spec.to_yaml())
```

The resulting document will contain `image/png` content in the response:
```yaml
openapi: 3.1.0
info:
  title: API
  version: 1.0.0
paths:
  /foo:
    get:
      responses:
        '200':
          description: OK
          content:
            image/png:
              schema: {}
```