flask-swagger

A Swagger 2.0 spec extractor for Flask

Install:

pip install flask-swagger

Flask-swagger provides a method (swagger) that inspects the Flask app for endpoints that contain YAML docstrings with Swagger 2.0 Operation objects.

class UserAPI(MethodView):

    def post(self):
        """
        Create a new user
        ---
        tags:
          - users
        definitions:
          - schema:
              id: Group
              properties:
                name:
                 type: string
                 description: the group's name
        parameters:
          - in: body
            name: body
            schema:
              id: User
              required:
                - email
                - name
              properties:
                email:
                  type: string
                  description: email for user
                name:
                  type: string
                  description: name for user
                address:
                  description: address for user
                  schema:
                    id: Address
                    properties:
                      street:
                        type: string
                      state:
                        type: string
                      country:
                        type: string
                      postalcode:
                        type: string
                groups:
                  type: array
                  description: list of groups
                  items:
                    $ref: "#/definitions/Group"
        responses:
          201:
            description: User created
        """
        return {}

Flask-swagger supports docstrings in methods of MethodView classes (ala Flask-RESTful) and regular Flask view functions.

Following YAML conventions, flask-swagger searches for ---, everything preceding is provided as summary (first line) and description (following lines) for the endpoint while everything after is parsed as a swagger Operation object.

In order to support inline definition of Schema objects in Parameter and Response objects, flask-swagger veers a little off from the standard. We require an id field for the inline Schema which is then used to correctly place the Schema object in the Definitions object.

Schema objects can be defined in a definitions section within the docstrings (see group object above) or within responses or parameters (see user object above). We also support schema objects nested within the properties of other Schema objects. An example is shown above with the address property of User.

To expose your Swagger specification to the world you provide a Flask route that does something along these lines

from flask import Flask, jsonify
from flask_swagger import swagger

app = Flask(__name__)

@app.route("/spec")
def spec():
    return jsonify(swagger(app))

Note that the Swagger specification returned by swagger(app) is as minimal as it can be. It's your job to override and add to the specification as you see fit.

@app.route("/spec")
def spec():
    swag = swagger(app)
    swag['info']['version'] = "1.0"
    swag['info']['title'] = "My API"
    return jsonify(swag)

Swagger-UI

Swagger-UI is the reason we embarked on this mission to begin with, flask-swagger does not however include Swagger-UI. Simply follow the awesome documentation over at https://github.com/swagger-api/swagger-ui and point your swaggerUi.url to your new flask-swagger endpoint and enjoy.

flaskswagger Command

This package now comes with a very simple command line interface: flaskswagger. This command can be used to build and update swagger specs for your flask apps from the command line or at build time.

flaskswagger -h

usage: flaskswagger [-h] [--template TEMPLATE] [--out-dir OUT_DIR] app

positional arguments:
  app                  the flask app to swaggerify

optional arguments:
  -h, --help           show this help message and exit
  --template TEMPLATE  template spec to start with
  --out-dir OUT_DIR    the directory to output to

For example, this can be used to build a swagger spec which can be served from your static directory. In the example below, we use the manually created swagger.json.manual as a template, and output to the static/ directory.

flaskswagger server:app --template static/swagger.json.manual --out-dir static/

Acknowledgements

Flask-swagger builds on ideas and code from flask-sillywalk and flask-restful-swagger

Notable forks

Flasgger