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Extract swagger specs from your flask-restful project. Project based on flask-restful-swagger-2 by Soeren Wegener.

Project description

What is flask-restful-swagger-3?

flask-restful-swagger-3 is a wrapper for flask-restful which enables swagger3 support according to the openapi 3.0.0 specification.

This project is based on flask-restful-swagger-2, but it only supported swagger 2.0.

Getting started


pip install flask-restful-swagger-3

To use it, change your import from from flask_restful import Api to from flask_restful_swagger_3 import Api.

from flask import Flask
# Instead of using this: from flask_restful import Api
# Use this:
from flask_restful_swagger_3 import Api

app = Flask(__name__)

# Use the swagger Api class as you would use the flask restful class.
# It supports several (optional) parameters, these are the defaults:
api = Api(app, version='0.0', api_spec_url='/api/swagger')

The Api class supports the following parameters:

Parameter Description
add_api_spec_resource Set to True to add an endpoint to serve the swagger specification (defaults to True).
version The API version string (defaults to ‘0.0’). Maps to the version field of the info object.
api_spec_base Instead of specifying individual swagger fields, you can pass in a minimal OpenAPI Object to use as a template. Note that parameters specified explicity will overwrite the values in this template.
api_spec_url The URL path that serves the swagger specification document (defaults to /api/swagger). The path is appended with .json and .html (i.e. /api/swagger.json and /api/swagger.html).
servers The server on which the API is served, it replaces schemes, host and base_path server object.
schemas The Schema Object allows the definition of input and output data types. Maps to the `schema <>`__
content A list of MIME types the API can consume. Maps to the `contents <>`__ field of the components.
contact The contact information for the API. Maps to the contact field of the info object.
description A short description of the application. Maps to the description field of the info object.
external_docs Additional external documentation. Maps to the externalDocs field of the operation object.
license The license information for the API. Maps to the license field of the info object.
parameters The parameters that can be used across operations. Maps to the parameters field of the operation object.
responses The responses that can be used across operations. Maps to the responses field of the operation object.
security A declaration of which security mechanisms can be used across the API. The list of values includes alternative security requirement objects that can be used. Only one of the security requirement objects need to be satisfied to authorize a request. Individual operations can override this definition. Maps to the security field of the OpenAPI Object.
securitySchemes The security schemes for the API. Maps to the securitySchemes field of the component object.
tags A list of tags used by the specification with additional metadata. Maps to the tags field fo the OpenAPI Object.
terms The terms of service for the API. Maps to the termsOfService field of the info object.
title The title of the application (defaults to the flask app module name). Maps to the title field of the info object.

Documenting API endpoints

Decorate your API endpoints with @swagger.doc. It takes a dictionary in the format of an operation object.

class UserItemResource(Resource):
        'tags': ['user'],
        'description': 'Returns a user',
        'parameters': [
                'name': 'user_id',
                'description': 'User identifier',
                'in': 'path',
                'schema': {
                    'type': 'integer'
        'responses': {
            '200': {
                'description': 'User',
                'content': {
                    'application/json': {
                        'schema': UserModel,
                        'examples': {
                            'application/json': {
                                'id': 1,
                                'name': 'somebody'
    def get(self, user_id):
        # Do some processing
        return UserModel(id=1, name='somebody'}), 200  # generates json response {"id": 1, "name": "somebody"}

Use add_resource as usual.

api.add_resource(UserItemResource, '/api/users/<int:user_id>')

Parsing query parameters

If a resource function contains the special argument _parser, any query type parameters in the documentation will be automatically added to a reqparse parser and assigned to the _parser argument.

Using models

Create a model by inheriting from flask_restful_swagger_3.Schema

from flask_restful_swagger_2 import Schema

class EmailModel(Schema):
    type = 'string'
    format = 'email'

class KeysModel(Schema):
    type = 'object'
    properties = {
        'name': {
            'type': 'string'

class UserModel(Schema):
    type = 'object'
    properties = {
        'id': {
            'type': 'integer',
            'format': 'int64',
        'name': {
            'type': 'string'
        'mail': EmailModel,
        'keys': KeysModel.array()
    required = ['name']

You can build your models according to the swagger schema object specification

It is recommended that you always return a model in your views so that your code and documentation are in sync.

RequestParser support

You can specify RequestParser object if you want to pass its arguments to spec. In such case, there is not need to define model manually

from flask_restful.reqparse import RequestParser

from flask_restful_swagger_2 import swagger, Resource

class GroupResource(Resource):
    post_parser = RequestParser()
    post_parser.add_argument('name', type=str, required=True)
    post_parser.add_argument('id', type=int, help='Id of new group')
        'tags': ['groups'],
        'description': 'Adds a group',
        'reqparser': {'name': 'group parser',
                      'parser': post_parser},
        'responses': {
            '201': {
                'description': 'Created group',
                'content': {
                    'application/json': {
                        'examples': {
                            'application/json': {
                                'id': 1
    def post(self):

Swagger schema (among other things):

{"GroupsModel": {
    "properties": {
        "id": {
            "default": null,
            "description": "Id of new group",
            "name": "id",
            "required": false,
            "type": "integer"
        "name": {
            "default": null,
            "description": null,
            "name": "name",
            "required": true,
            "type": "string"
    "type": "object"

Using authentication

In the example above, the view UserItemResource is a subclass of Resource, which is provided by flask_restful. However, flask_restful_swagger_3 provides a thin wrapper around Resource to provide authentication. By using this, you can not only prevent access to resources, but also hide the documentation depending on the provided api_key.


# Import Api and Resource instead from flask_restful_swagger_2
from flask_restful_swagger_3 import Api, swagger, Resource

api = Api(app)
def auth(api_key, endpoint, method):
    # Space for your fancy authentication. Return True if access is granted, otherwise False
    # api_key is extracted from the url parameters (?api_key=foo)
    # endpoint is the full swagger url (e.g. /some/{value}/endpoint)
    # method is the HTTP method
    return True

swagger.auth = auth

class MyView(Resource):
    # documentation...
    def get(self):
        return SomeModel(value=5)

api.add_resource(MyView, '/some/endpoint')

Specification document

The get_swagger_doc method of the Api instance returns the specification document object, which may be useful for integration with other tools for generating formatted output or client code.

Using Flask Blueprints

To use Flask Blueprints, create a function in your views module that creates the blueprint, registers the resources and returns it wrapped in an Api instance:

from flask import Blueprint, request
from flask_restful_swagger_3 import Api, swagger, Resource

class UserResource(Resource):

class UserItemResource(Resource):

def get_user_resources():
    Returns user resources.
    :param app: The Flask instance
    :return: User resources
    blueprint = Blueprint('user', __name__)

    api = Api(blueprint, add_api_spec_resource=False)

    api.add_resource(UserResource, '/api/users')
    api.add_resource(UserItemResource, '/api/users/<int:user_id>')

    return api

In your initialization module, collect the swagger document objects for each set of resources, then use the get_swagger_blueprint function to combine the documents and specify the URL to serve them at (default is ‘/api/doc/swagger’). Note that the get_swagger_blueprint function accepts the same keyword parameters as the Api class to populate the fields of the combined swagger document. Finally, register the swagger blueprint along with the blueprints for your resources.

from flask_restful_swagger_3 import get_swagger_blueprint


# A list of swagger document objects
docs = []

# Get user resources
user_resources = get_user_resources()

# Retrieve and save the swagger document object (do this for each set of resources).

# Register the blueprint for user resources

# Prepare a blueprint to serve the combined list of swagger document objects and register it
app.register_blueprint(get_swagger_blueprint(docs, '/api/doc/swagger', title='Example', api_version='1'))

Refer to the files in the example folder for the complete code.

Running and testing

To run the example project in the example folder:

pip install flask-restful-swagger-3
pip install flask-cors    # needed to access spec from swagger-ui

To run the example which uses Flask Blueprints:


The swagger spec will by default be at http://localhost:5000/api/doc/swagger.json. You can change the URL by passing api_spec_url='/my/path' to the Api constructor. You can use swagger-ui to explore your api. Try it online at

To run tests:

pip install tox # needed to run pytest

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