aiohttp-apispec 1.4.0

Build and document REST APIs with aiohttp and apispec

aiohttp-apispec

Build and document REST APIs with aiohttp and apispec

aiohttp-apispec key features:

• docs and request_schema decorators to add swagger spec support out of the box;
• validation_middleware middleware to enable validating with marshmallow schemas from those decorators;
• SwaggerUI support.

aiohttp-apispec api is fully inspired by flask-apispec library

Contents

• Install
• Quickstart
• Adding validation middleware
• Custom error handling
• Build swagger web client

Install

pip install aiohttp-apispec

Quickstart

from aiohttp_apispec import (
    docs,
    request_schema,
    setup_aiohttp_apispec,
)
from aiohttp import web
from marshmallow import Schema, fields


class RequestSchema(Schema):
    id = fields.Int()
    name = fields.Str(description="name")

@docs(
    tags=["mytag"],
    summary="Test method summary",
    description="Test method description",
)
@request_schema(RequestSchema(strict=True))
async def index(request):
    return web.json_response({"msg": "done", "data": {}})


app = web.Application()
app.router.add_post("/v1/test", index)

# init docs with all parameters, usual for ApiSpec
setup_aiohttp_apispec(
    app=app, 
    title="My Documentation", 
    version="v1",
    url="/api/docs/swagger.json",
    swagger_path="/api/docs",
)

# Now we can find spec on 'http://localhost:8080/api/docs/swagger.json'
# and docs on 'http://localhost:8080/api/docs'
web.run_app(app)

Class based views are also supported:

class TheView(web.View):
    @docs(
        tags=["mytag"],
        summary="View method summary",
        description="View method description",
    )
    @request_schema(RequestSchema(strict=True))
    @response_schema(ResponseSchema(), 200)
    def delete(self):
        return web.json_response(
            {"msg": "done", "data": {"name": self.request["data"]["name"]}}
        )


app.router.add_view("/v1/view", TheView)

As alternative you can add responses info to docs decorator, which is more compact way. And it allows you not to use schemas for responses documentation:

@docs(
    tags=["mytag"],
    summary="Test method summary",
    description="Test method description",
    responses={
        200: {
            "schema": ResponseSchema,
            "description": "Success response",
        },  # regular response
        404: {"description": "Not found"},  # responses without schema
        422: {"description": "Validation error"},
    },
)
@request_schema(RequestSchema(strict=True))
async def index(request):
    return web.json_response({"msg": "done", "data": {}})

Adding validation middleware

from aiohttp_apispec import validation_middleware

...

app.middlewares.append(validation_middleware)

Now you can access all validated data in route from request['data'] like so:

@docs(
    tags=["mytag"],
    summary="Test method summary",
    description="Test method description",
)
@request_schema(RequestSchema(strict=True))
@response_schema(ResponseSchema(), 200)
async def index(request):
    uid = request["data"]["id"]
    name = request["data"]["name"]
    return web.json_response(
        {"msg": "done", "data": {"info": f"name - {name}, id - {uid}"}}
    )

You can change Request's 'data' param to another with request_data_name argument of setup_aiohttp_apispec function:

setup_aiohttp_apispec(
    app=app,
    request_data_name="validated_data",
)

...


@request_schema(RequestSchema(strict=True))
async def index(request):
    uid = request["validated_data"]["id"]
    ...

Custom error handling

If you want to catch validation errors by yourself you could use error_callback parameter and create your custom error handler. Note that it can be one of coroutine or callable and it should have interface exactly like in examples below:

from marshmallow import ValidationError, Schema
from aiohttp import web
from typing import Optional, Mapping, NoReturn


def my_error_handler(
    error: ValidationError,
    req: web.Request,
    schema: Schema,
    error_status_code: Optional[int] = None,
    error_headers: Optional[Mapping[str, str]] = None,
) -> NoReturn:
    raise web.HTTPBadRequest(
            body=json.dumps(error.messages),
            headers=error_headers,
            content_type="application/json",
        )

setup_aiohttp_apispec(app, error_callback=my_error_handler)

Also you can create your own exceptions and create regular Request in middleware like so:

class MyException(Exception):
    def __init__(self, message):
        self.message = message

# It can be coroutine as well:
async def my_error_handler(
    error, req, schema, error_status_code, error_headers
):
    await req.app["db"].do_smth()  # So you can use some async stuff
    raise MyException({"errors": error.messages, "text": "Oops"})

# This middleware will handle your own exceptions:
@web.middleware
async def intercept_error(request, handler):
    try:
        return await handler(request)
    except MyException as e:
        return web.json_response(e.message, status=400)


setup_aiohttp_apispec(app, error_callback=my_error_handler)

# Do not forget to add your own middleware before validation_middleware
app.middlewares.extend([intercept_error, validation_middleware])

Build swagger web client

3.X SwaggerUI version

Just add swagger_path parameter to setup_aiohttp_apispec function.

For example:

setup_aiohttp_apispec(app, swagger_path="/docs")

Then go to /docs and see awesome SwaggerUI

2.X SwaggerUI version

If you prefer older version you can use aiohttp_swagger library. aiohttp-apispec adds swagger_dict parameter to aiohttp web application after initialization (with setup_aiohttp_apispec function). So you can use it easily like:

from aiohttp_apispec import setup_aiohttp_apispec
from aiohttp_swagger import setup_swagger


def create_app(app):
    setup_aiohttp_apispec(app)

    async def swagger(app):
        setup_swagger(
            app=app, swagger_url="/api/doc", swagger_info=app["swagger_dict"]
        )

    app.on_startup.append(swagger)
    # now we can access swagger client on '/api/doc' url
    ...
    return app

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