Sanic OpenAPI v3e

OpenAPI v3 support for Sanic. Document and describe all parameters, including sanic path params. python 3.6+; sanic 18.12.0+ but sanic 20.12.0 and later are recommended.

Installation

pip install sanic-openapi3e

Usage

Import blueprint and use simple decorators to document routes:

import sanic
import sanic.response
from sanic_openapi3e import openapi_blueprint, swagger_blueprint, doc

app = sanic.Sanic(strict_slashes=True)
app.blueprint(openapi_blueprint)
app.blueprint(swagger_blueprint)

@app.get("/user/<user_id>")
@doc.summary("Fetches a user by ID")
@doc.response(200, "The user")
async def get_user(request, user_id):
    return sanic.response.json({"user_id": user_id})

app.go_fast()

You'll now have a specification at the URL /openapi/spec.json and a YAML version at /openapi/spec.yml.

p.s.: Clicking on the /openapi/spec.yml link in a browser will generally download a file and your computer will open an application to read it. To see the YAML spec in the browser as a plain text file, add a ?as_text query string like /openapi/spec.yml?as_text instead.

Your routes will be automatically categorized by their blueprints' names.

Below are some simple examples, which you can copy/paste, run, and point your browser to http://127.0.0.1:8000/swagger/ to see them in action.

Describe route path parameters

If you have path parameters, you will want to describe them:

import sanic
import sanic.response
from sanic_openapi3e import openapi_blueprint, swagger_blueprint, doc
app = sanic.Sanic(strict_slashes=True)
app.blueprint(openapi_blueprint)
app.blueprint(swagger_blueprint)

@app.get("/examples/test_id/<an_id:int>")
@doc.parameter(name="an_id", description="An ID", required=True, _in="path")
def test_id(request, an_id):
    d = locals()
    del d["request"]  # not JSON serializable
    return sanic.response.json(d)

app.go_fast()

sanic-openapiv3e will recognise that the path parameter an_id is described with @doc.parameter and will merge the details together.

You may wish to specify that a parameter be limited to a set of choices, such as day-of-week or that it has a minimum value. These can be done for parameters in path, query, header and cookie:

import sanic
import sanic.request
import sanic.response
from sanic_openapi3e import openapi_blueprint, swagger_blueprint, doc

app = sanic.Sanic(strict_slashes=True)
app.blueprint(openapi_blueprint)
app.blueprint(swagger_blueprint)

int_min_4 = doc.Schema(
    _type="integer", _format="int32", minimum=4, description="Minimum: 4"
)  

@app.get("/test/some_ids")
@doc.parameter(
    name="ids",
    description="Some IDs",
    required=True,
    choices=[1, 3, 5, 7, 11, 13],
    _in="query",
    schema=doc.Schema.Integers,
)
def test_some_ids(request: sanic.request.Request):
    query = request.query_string
    return sanic.response.json(query)



@app.get("/examples/test_id_min/<an_id:int>")
@doc.parameter(
    name="an_id", description="An ID", required=True, _in="path", schema=int_min_4
)
def test_id_min(request, an_id: int):
    d = locals()
    del d["request"]  # not JSON serializable
    return sanic.response.json(d)

app.go_fast()

Describe your tags

OpenAPI uses "tags" (there can be more than one per route) to group the endpoints. It's nice to be able to group your endpoints into tags given by the blueprint's name, but sometimes you will want to give them better names: @doc.tag("tag name"). Better still is to give a description to these tags (which shows up nicely in Swagger UI), so @doc.tag("tag name", description="tag description").

You don't have to add the description more than once, sanic-openapiv3e will make it available, so while you'll want to decorate each endpoint with @doc.tag(...), only one of these will need the description. If you try to set different descriptions for the same tag, sanic-openapiv3e will raise an exception showing the tag name and the conflicting descriptions.

Share and reuse common parameters in your app

You probably have some common parameters that appear in many places in your API. Days of the week? Pagination where the minimum value must be greater than zero? OpenAPI v3 has the concept of "components" which can be shared. Setting them up is easy:

import sanic.request
import sanic.response
from sanic import Sanic
from sanic_openapi3e import openapi_blueprint, swagger_blueprint, doc


days_of_week = doc.Schema(
    _type="string",
    description="Days of the week, short, English",
    enum=["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"],
)

app = Sanic(strict_slashes=True)
app.blueprint(openapi_blueprint)
app.blueprint(swagger_blueprint)

schemas = {
    "int.min4": doc.Schema(
        title="int.min4",
        _type="integer",
        _format="int32",
        minimum=4,
        description="Minimum: 4",
    ),
    "days": days_of_week,
}
components = doc.Components(schemas=schemas)
app.config.OPENAPI_COMPONENTS = components

# ^^ the line above adds these to OAS v3's "components"
# the next two, which would ordinarily live in your blueprints's module,
# reuse these shared components.
int_min_4_ref = doc.Reference("#/components/schemas/int.min4")
dow_ref = doc.Reference("#/components/schemas/days")


@app.get("/simple/01/from/<start>/to/<end>/in/<hops:int>")
@doc.parameter(
    name="start", description="Start day", required=True, _in="path", schema=dow_ref
)
@doc.parameter(
    name="end", description="End day", required=True, _in="path", schema=dow_ref
)
@doc.parameter(
    name="hops",
    description="hops to use",
    required=True,
    _in="path",
    schema=int_min_4_ref,
)
def get_start_end_hops(request, start: str, end: str, hops: int):
    d = locals()
    del d["request"]  # not JSON serializable
    return sanic.response.json(d)


app.go_fast()

Deprecate route paths and/or parameters

A parameter can be marked as deprecated=True:

import sanic
import sanic.request
import sanic.response
from sanic_openapi3e import openapi_blueprint, swagger_blueprint, doc

app = sanic.Sanic(strict_slashes=True)
app.blueprint(openapi_blueprint)
app.blueprint(swagger_blueprint)

@app.get("/examples/test_parameter__deprecated/<an_id:int>")
@doc.parameter(
    name="an_id", description="An ID", required=True, _in="path", deprecated=True
)
@doc.summary("A path deprecated parameter")
@doc.description("The parameter should be marked as deprecated")
def param__deprecated(request, an_id: int):
    d = locals()
    del d["request"]  # not JSON serializable
    return sanic.response.json(d)

app.go_fast()

as can a whole route with @doc.deprecated():

import sanic
import sanic.request
import sanic.response
from sanic_openapi3e import openapi_blueprint, swagger_blueprint, doc

app = sanic.Sanic(strict_slashes=True)
app.blueprint(openapi_blueprint)
app.blueprint(swagger_blueprint)

@app.get("/examples/test_path__deprecated/<an_id:int>")
@doc.parameter(
    name="an_id",
    description="An ID",
    required=True,
    _in="path",
)
@doc.summary("A path with parameter examples")
@doc.description("This is marked as being deprecated")
@doc.deprecated()
def path__deprecated(request, an_id: int):
    d = locals()
    del d["request"]  # not JSON serializable
    return sanic.response.json(d)

app.go_fast()

Please note, that while many python decorators can be called without the (), this one really does require the () at the end of @doc.deprecated().

Exclude routes from appearing in the OpenAPI spec (and swagger)

Need to soft-launch an endpoint, or keep your swagger simple? Add a @doc.exclude and it won't be in the OpenAPI spec at all (unless you have set your app.config.SHOW_OPENAPI_EXCLUDED = True when a second spec at /openapi/spec.all.json will be created which will have all routes, including excluded.

import sanic
import sanic.request
import sanic.response
from sanic_openapi3e import openapi_blueprint, swagger_blueprint, doc

app = sanic.Sanic(strict_slashes=True)
app.blueprint(openapi_blueprint)
app.blueprint(swagger_blueprint)

@app.get("/test/alpha_release")
@doc.exclude
@doc.parameter(
    name="ids",
    description="Some IDs",
    required=True,
    choices=[1, 3, 5, 7, 11, 13],
    _in="query",
    schema=doc.Schema.Integers,
)
def test_some_ids(request: sanic.request.Request):
    query = request.query_string
    return sanic.response.json(query)

app.go_fast()

Predefined components for responses

There are predefimed components for common responses. You can overwrite and append these per route.

Control spec generation

app.config.API_VERSION = '1.0.0'
app.config.API_TITLE = 'An API'
app.config.API_DESCRIPTION = 'An API description'

To have a contact, set at least one of (but preferably all) app.config.API_CONTACT_NAME, app.config.API_CONTACT_URL or app.config.API_CONTACT_EMAIL.

To have a license, set app.config.API_LICENSE_NAME and optionally app.config.API_LICENSE_URL (all str, but the Swagger UI expects this to be a URL).

To have a termsOfService, set app.config.API_TERMS_OF_SERVICE_URL (a str, but the Swagger UI expects to use this as a URL).

Setting components, security and externalDocs requires you to

• first create the relevant objects somewhere in your code (near to where you create the app),
• set the appropriate app.config.OPENAPI_COMPONENTS, app.config.OPENAPI_SECURITY,
  app.config.OPENAPI_EXTERNAL_DOCS.

By default, the YAML spec is served on /openapi/spec.yml with the content-type of application/x-yaml but you can overwrite that by setting app.config.OPENAPI_YAML_CONTENTTYPE to something like text/plain. This lets you view your spec in a browser, and it still works with /swagger :-)

Configure how the operationId is made

The default code for creating the operationId creates unique (as they must be) strings from the following code:

def default_operation_id_fn(method: str, uri: str, route: sanic.router.Route) -> str:
    uri_for_operation_id: str = uri
    for parameter in route.parameters:
      uri_for_operation_id = re.sub(
            "<" + parameter.name + ".*?>", parameter.name, uri_for_operation_id
        )

    return "{}~~{}".format(method.upper(), uri_for_operation_id).replace("/", "~")

You can implement your own code (as long as the method signature matches this), and set that to be used in the app config: app.config.OPENAPI_OPERATION_ID_FN = my_operation_id_fn

For example, to make camelCase operationIds from the Routes' handlers (but be advised you that you must ensure your handlers' function names are globally unique, not "just" unique within the Blueprint), you could use the supplied camel_case_operation_id_fn:

def camel_case_operation_id_fn(method: str, uri: str, route: sanic.router.Route) -> str:

  if hasattr(route.handler, "__class__") and hasattr(route.handler, "handlers"):
    # These are `sanic.view.CompositeView`s
    _method_handler = route.handler.handlers.get(method.upper())
    if _method_handler:
      handler_name = method + "_" + _method_handler.__name__
    else:
      raise ValueError(f"No {method.upper()} handler found for {uri} handlers: {route.handler.handlers}")
  elif hasattr(route.handler, "__name__"):
    if len(route.methods) > 1:
      # This fn will be called many times, once per method, but we should prefix the handler_name with this
      # prefix to make the operationIds globally unique. If the route is only used by one method, use that
      # handler's name.
      handler_name = method + "_" + route.handler.__name__
    else:
      handler_name = route.handler.__name__
  else:
    raise NotImplementedError()
  return simple_snake2camel(handler_name)

and set it like app.config.OPENAPI_OPERATION_ID_FN = sanic_openapi3e.openapi.camel_case_operation_id_fn

Note that this does not change the parameter's names.

hide_openapi_self = app.config.get("HIDE_OPENAPI_SELF", True)
show_excluded = app.config.get("SHOW_OPENAPI_EXCLUDED", False)
show_unused_tags = app.config.get("SHOW_OPENAPI_UNUSED_TAGS", False)

In practice, you don't usually want to document the /swagger nor /openapi routes, but by setting app.config.HIDE_OPENAPI_SELF = False you can have them appear in the generated spec (and therefore swagger too).

Your @doc.exclude annotations are always respected, but if your config has app.config.SHOW_OPENAPI_EXCLUDED = True then a second spec at /openapi/spec.all.json is created. You generally won't want these to be on your production deployment, but you may want it for dev and test purposes.

OAS Object maturity

sanic-openapi3e is being used in production, and all of the spec is implemented. Most of the spec is known to be in production use, but some of the spec's objects are marked here as "beta" due to no known production use.

sanic-openapi3e is built to create OpenAPI 3.0.2 specs.

Changelog

• v0.9.10
  • Adds CORS Access-Control-Allow-Origin: * headers to the OpenAPI /openapi/spec* endpoints.
• v0.9.9
  • Fixes type validation bug for oneOf.
• v0.9.8
  • Further extends complex Schema objects by extending how allOf, oneOf, anyOf, and not are handled.
• v0.9.7
  • Extends the ability to define complex Schema objects.
• v0.9.6
  • Fixes a bug where None values in examples would cause a runtime error.
• v0.9.5
  • Improves how the .components.responses are rendered.
  • Fixes issues with the "static"/"frozen" predefined Schema objects.
• v0.9.4
  • Adds a @doc.responses() to give an easier way of documenting a route.
• v0.9.3
  • Adds a @doc.security() to override security requirements on a route.
  • Removes entries with false values from the spec if false is the default value. This makes the specs smaller and are more idiomatic.
• v0.9.2
  • Fixes an issue of rendering SecurityRequirement when there were no entries in the list.