PyCon Korea 2019 REST API Document Generation

PyCon Korea 2019
AITRICS
REST API

5

Python backend app

Flask 2 Django

●REST API

●OpenAPI Specification

●Python Web Applications & OpenAPI Specification

●Django API

●Flask API

REST API ?
HTTP
METHODS
https://api.example.com/speakers https://api.example.com/speakers/1
GET 1
POST -
PUT
request body
request body field null
1 request body
request body field null
PATCH
request body
request body field
1 request body
request body field
DELETE 1
OpenAPI Specification Python Web Apps & OAS Django FlaskREST API
Representational State Transfer

( API )
REST API

●API ,

●Host, port

●

●URI

●URI HTTP method

● request header, body

● response status code, body
REST API

REST API

.. 

● ..

●

●
REST API

RESTful API

JSON, YAML

API , /  
Swagger OpenAPI Initiative
OpenAPI Specification
https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md
REST API Python Web Apps & OAS Django FlaskOpenAPI Specification

API

toolset

●Swagger Codegen

●Swagger Editor

●Swagger UI

Swagger UI
●OpenAPI JSON/YAML  
API
Swagger?
https://petstore.swagger.io/

title: Sample PyCON speaker API

description: This is a sample server for a PyCON speaker management.

termsOfService: http://example.com/terms/

contact:

name: API Support

url: http://www.example.com/support

email: support@example.com

license:

name: MIT

version: 1.0.1
OpenAPI Specification YAML

servers:

- url: https://pycon-speaker.com:{port}/{basePath}

description: The production API server

variables:

port:

enum:

- '443'

- '8443'

default: '8443'

description: 8443 is for demo.

basePath:

default: v2

paths:

/speakers:

get:

description: Returns all speakers from the system that the user has access to

responses:

'200':

description: A list of speakers.

content:

application/json:

schema:

type: array

items:

$ref: '#/components/schemas/Speaker'

components:

schemas:

Speaker:

required:

- id

- email

properties:

id:

type: integer

format: int64

email:

type: string

name:

type: string


OpenAPI Specification 
JSON / YAML
APISwagger UI
paths:

/speakers:

get:

description: Returns all speakers from the system
that the user has access to

responses:

'200':


content:

application/json:

schema:

type: array

items:


Python Web Application &  
OpenAPI Specification

Generating OpenAPI YAML
Web Application Server
●Server information

○Base URL, port, ...

●Routing information

○ path

●Request params

●Response schema
REST API OpenAPI Specification Django FlaskPython Web Apps & OAS

servers:

- url: https://pycon-speaker.com:{port}/{basePath}

description: The production API server

variables:

port:

enum:

- '443'

- '8443'

default: '8443'

description: 8443 is for demo.

basePath:

default: v2

○Routing information

■ Request params

■ Response schema

paths:

/speakers:

get:

description: Returns all speakers

responses:

'200':


content:

application/json:

schema:

type: array

items:


○Routing information

■ Request params

■ Response schema

Django & OAS
Django Server
●Server information →

○Routing information → urls.urlpatterns

■ Request params → View, Model

■ Response schema → View, Model

Django & OAS
Server Information
● ,

Routing Information
●urlpatterns
# urls.py

openapi_schema_view = get_schema_view(

openapi.Info(

title='Demo API',

default_version='v1',

),

url='https://demo.example.com:3000',

public=True,

)

urlpatterns = [

path('admin/', admin.site.urls),

path('docs/', openapi_schema_view.with_ui(...),

path('', include(router.urls)),

]

Django & OAS
Request Params, Response Schema
●Function Based View
○ view request, response

■ docstring ? 
→ API
def speakers_list(request):

"""

response

- type: list

- content

- name: , string

- email: , string

- organization: , object

- name: , string

"""

...

return speakers

django/views/generics/edit.py
Django & OAS
●Class Based View
○django/views/generics

○cls.model model  
→ response schema

○cls.get_form_class() form  
→ request parameters
CreateView
ModelFormMixin
get_form_class()
SingleObjectMixin
model

Flask & OAS
Flask Server
●Server information →

○Routing information → Flask.view_functions

■ Request params → View?, Model?

■ Response schema → View?, Model?

Flask & OAS
Routing Information
●Flask.view_functions
# flask/app.py: Flask

def route(self, rule, **options):

def decorator(f):

endpoint = options.pop('endpoint', None)

self.add_url_rule(rule, endpoint, f, **options)

return f

return decorator

def add_url_rule(self, rule, endpoint, view_func, ...):

…

self.view_functions[endpoint] = view_func

…

Flask & OAS
●Function View (Django )
○ view request, response

■ docstring ? → API

●Pluggable View(Class Based View)
○Function View Extension

○

●Routing information
○ framework routing

●Request params
○(Django) View class form

●Response schema
○(Django) View class model

●APIView (Django view wrapping)

●ModelViewSet (generic views)

○Serializer

○Filterset

○Permission

●OpenAPI schema ( )
Django REST Framework
REST API OpenAPI Specification Python Web Apps & OAS FlaskDjango



○Serializer
○Filterset

○Permission

>>> speaker

<Speaker: Speaker object (1)>

>>> serializer = SpeakerSerializer(speaker)

>>> serializer.data

{'email': 'test@pycon.kr',

'name': 'test',

'created': '2019-08-18T12:15:10.375877'}



○Serializer
○Filterset

○Permission

>>> data = {'email': 'another@pycon.kr',

'name': 'another test',

'created': '2019-08-18T12:16:10.375877'}

>>> serializer = SpeakerSerializer(data=data)

>>> serializer.is_valid()

True

>>> serializer.validated_data

{'email': 'another@pycon.kr',

'name': 'another test',

'created': datetime.datetime(2019, 08, 18, 12, 16, 10,
375877)}



○Serializer
○Filterset

○Permission

>>> serializer.save()

<Speaker: Speaker object (2)>



○Serializer
○Filterset

○Permission


API

●Django REST Swagger

○ https://github.com/marcgibbons/django-rest-swagger 
●DRF Yet another Swagger generator

○ https://github.com/axnsan12/drf-yasg

○ swagger/redoc UI
https://www.django-rest-framework.org/topics/documenting-your-api/


API

●Django REST Swagger

○ https://github.com/marcgibbons/django-rest-swagger

○ 2019-06-04 Deprecated… 
●DRF Yet another Swagger generator

○ https://github.com/axnsan12/drf-yasg

○ swagger/redoc UI

○
https://www.django-rest-framework.org/topics/documenting-your-api/


●View serializer request / response schema

● override decorator

●OpenAPI Spec 2.0 schema

○DRF OpenAPI schema
DRF-YASG

DRF native vs DRF-YASG
# Django REST Framework (X)

responses:

'200':

content:

application/json:

schema:

properties:

id:

type: integer

readOnly: true

date:

type: string

format: date

packages:

type: array

items:

type: string
# DRF-YASG (O)

responses:

'200':

schema:

type: object

properties:

count:

type: integer

next:

type: string

format: uri

previous:

type: string

format: uri

results:

type: array

items:

$ref: '#/definitions/Record'

DRF-YASG
urlpatterns

(url → view class mappings)
/speakers → SpeakerViewSet
serializer class = SpeakerSerializer
/organizations → OrganizationViewSet
serializer class = OrganizationSerializer

DRF-YASG
urlpatterns
SpeakerViewSet
serializer class
Speaker

(id, name, email,
organization_id)
SpeakerSerializer
model = Speaker

id: int

name: str

email: str

organization_id: int, read-only

organization:

OrganizationSerializer, write-only

DRF-YASG
urlpatterns
SpeakerViewSet
serializer class
SpeakerSerializer
model = Speaker

id: int

name: str

email: str

organization_id: int, read-only

organization:

OrganizationSerializer, write-only
OrganizationSerializer
model = Organization

id: int

name: str

DRF-YASG
# drf_yasg/views.py

class SchemaView(APIView):

...

def get(self, request, version='', format=None):

...

schema = generator.get_schema(request, self.public)

...

return Response(schema)

DRF-YASG
# drf_yasg/generators.py

class OpenAPISchemaGenerator:

def get_schema(self, request=None, public=False):

...

paths, prefix = self.get_paths(endpoints, ...)

...

return openapi.Swagger(

paths=paths,

...

)
def get_paths(self, endpoints, ...):

...

for url, (..., methods) in sorted(endpoints.items()):

...

for method, view in methods:

...

operation = self.get_operation(url, method, ...)

...

...

def get_operation(self, url, method, ...):

...

operation = view_inspector.get_operation(...)

...
urls.urlpatterns

DRF-YASG



...


...


paths=paths,

...

)

...

for path, (..., methods) in sorted(endpoints.items()):

...


...

operation = self.get_operation(path, method, ...)

...

...

def get_operation(self, path, method, ...):

...


...
paths:

/speakers:

get:


responses:

'200':


content:

application/json:

schema:

type: array

items:

urls.urlpatterns

DRF-YASG



...


...


paths=paths,

...

)

...

for url, (..., methods) in sorted(endpoints.items()):

...


...

operation = self.get_operation(url, method, ...)

...

...

def get_operation(self, url, method, ...):

...


...

DRF-YASG



...


...


paths=paths,

...

)

...


...


...


...

...


...


...
paths:

/speakers:

get:


responses:

'200':


content:

application/json:

schema:

type: array

items:


DRF-YASG



...


...


paths=paths,

...

)

...


...


...


...

...


...


...

DRF-YASG
# drf_yasg/inspectors/view.py

class SwaggerAutoSchema(ViewInspector):

def get_operation(self, operation_keys=None):

...

parameters = body + query

parameters = filter_none(parameters)

parameters = self.add_manual_parameters(parameters)

...

responses = self.get_responses()

return openapi.Operation(

parameters=parameters,

responses=responses,

...

)


DRF-YASG
# drf_yasg/inspectors/view.py

class SwaggerAutoSchema(ViewInspector):

def get_operation(self, operation_keys=None):

...

parameters = body + query

parameters = filter_none(parameters)

parameters = self.add_manual_parameters(parameters)

...

responses = self.get_responses()

return openapi.Operation(

parameters=parameters,

responses=responses,

...

)

1. self.view serializer

2. field inspector field

○ Nested serializer

○ SerializerMethodField

○ Paginated response

3. openapi Response

DRF-YASG
●urlpatterns endpoints(url → view mapping)  
●endpoints iterate url, method request response  
●request response field inspector  
Nested serializer  
● request response OpenAPI schema

DRF-YASG
# main/urls.py

...

openapi_schema_view = get_schema_view(

openapi.Info(

title='Demo API',

default_version='v1',

),

public=True,

)

urlpatterns = [

path('admin/', admin.site.urls),

path('docs/', openapi_schema_view.with_ui('redoc')),

path('', include(router.urls)),

]

DRF-YASG
# main/models.py

class Speaker(models.Model):

id = AutoField(primary_key=True)

email = EmailField()

name = CharField(max_length=10, blank=True)

organization = ForeignKey(

Organization,

null=True,

on_delete=models.SET_NULL,

related_name='speakers'

)

# main/views.py

class SpeakerViewSet(ModelViewSet):

queryset = Speaker.objects.all()

serializer_class = SpeakerSerializer

DRF-YASG
# main/serializers.py

class OrganizationSerializer(ModelSerializer):

...

class SpeakerSerializer(ModelSerializer):

organization = OrganizationSerializer(read_only=True,

help_text='Read-only ')

organization_id = PrimaryKeyRelatedField(source='organization',

queryset=Organization.objects.all(),

write_only=True,

help_text='Write-only ')

class Meta:

model = Speaker

fields = '__all__'

write_only_fields = ('organization_id',)

read_only_fields = ('organization',)

DRF-YASG
# main/serializers.py

class OrganizationSerializer(ModelSerializer):

...

class SpeakerSerializer(ModelSerializer):

organization = OrganizationSerializer(read_only=True,

help_text='Read-only ')

organization_id = PrimaryKeyRelatedField(source='organization',

queryset=Organization.objects.all(),

write_only=True,

help_text='Write-only ')

class Meta:

model = Speaker

fields = '__all__'

write_only_fields = ('organization_id',)

read_only_fields = ('organization',)
$ curl -X POST localhost:8000/speakers

-d "name=test&email=test@pycon.kr&organization_id=1"

{

"id": 1,

"name": "test",

"email": "test@pycon.kr",

"organization": {

"id": 1,

"name": "test organization"

}

}

DRF-YASG

DRF-YASG Custom Action
# main/views.py


queryset = Speaker.objects.all()


@action(methods=['get'], detail=False)

def count(self, _):

return Response({'result': Speaker.objects.count()})

Response schema  
!

# main/views.py


queryset = Speaker.objects


@swagger_auto_schema(

operation_description=' API',

responses={

'200': openapi.Response(

description='',

schema=openapi.Schema(

type='object',

properties={'result': openapi.Schema(type='integer')}

)

)

}

)


def count(self, _):


# main/views.py

class SpeakerCountSerializer(Serializer):

result = IntegerField()


queryset = Speaker.objects


@swagger_auto_schema(

operation_description=' API',

responses={'200': SpeakerCountSerializer}

)


def count(self, _):


DRF-YASG
●

○read_only, write_only

○serializer

●Redoc UI request

●Swagger UI

●OpenAPI Spec 2.0

DRF-YASG
●

○read_only, write_only

○serializer

●Redoc UI request

●Swagger UI

●OpenAPI Spec 2.0
https://swagger.io/blog/news/whats-new-in-openapi-3-0/

●Resource View get, post  
●arg parser View  
●field model marshal
Flask-RESTful
REST API OpenAPI Specification Python Web Apps & OAS Django Flask

●Flask-RESTful

○ Flask-RESTful API

● API

●Flask-RESTful
Flask-RESTPlus

●Flask RESTful Swagger 2.0

○ OpenAPI Spec 1.2

○ 2.0

●SQLAlchemy Flask RESTful Swagger (SAFRS)

○ DB model class

○ Model method docstring
API

Flask-RESTPlus


○ 2.0


○ DB model class

○ Model method docstring

Flask-RESTPlus


○ 2.0


○ DB model class

○ Model method docstring  
●Flask-RESTPlus

Flask-RESTPlus
from flask import Flask

from flask_sqlalchemy import SQLAlchemy

from flask_restplus import Api

app = Flask(__name__)

app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///db.sqlite3'

app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False

db = SQLAlchemy(app)

api = Api(app)


Flask-RESTPlus
class OrganizationModel(db.Model):

id = db.Column(db.Integer, primary_key=True, autoincrement=True)

name = db.Column(db.String(100), nullable=False)

class SpeakerModel(db.Model):

id = db.Column(db.Integer, primary_key=True, autoincrement=True)

name = db.Column(db.String(10), nullable=True)

email = db.Column(db.String(120), unique=True, nullable=False)

organization_id = db.Column(db.Integer, db.ForeignKey('organization_model.id'))

organization = relationship('OrganizationModel')

Flask-RESTPlus
organization_output = api.model('OrganizationOutput', {

'name': fields.String

})

speaker_output = api.model('SpeakerOutput', {

'name': fields.String,

'email': fields.String,

'organization': fields.Nested(organization_output)

})

speaker_input = reqparse.RequestParser()

speaker_input.add_argument('email', type=str)

speaker_input.add_argument('name', type=str)

speaker_input.add_argument('organization_id', type=int)


Flask-RESTPlus
@api.route('/speakers')

class Speaker(Resource):

@api.marshal_list_with(speaker_output)

def get(self):

return Speaker.query.all()

@api.expect(speaker_input)

@api.marshal_with(speaker_output)

def post(self):

args = speaker_input.parse_args()

speaker = SpeakerModel(**args)

db.session.add(speaker)

db.session.commit()

return speaker
$ curl -X POST localhost:5000/speakers

-d "name=test&email=test@pycon.kr&organization_id=1"

{

"name": "test",

"email": "test@pycon.kr",

"organization": {

"name": "test organization"

}

}

Flask-RESTPlus

●Web framework → OpenAPI YAML / JSON → Swagger / Redoc UI

● web framework(Bottle, Sanic, Vibora )  
runtime routing (path → view function)

○ OpenAPI schema

○ Sanic-RESTPlus

●drf-yasg, Flask-RESTPlus

www.aitrics.com
contact@aitrics.com
Yongseon Lee <yongseon@aitrics.com>
● REST API (Yongseon Lee)  
18th (Sun) 11:55 ~ 12:35
● Advanced Python testing techniques (Jaeman An) 
18th (Sun) 11:55 ~ 12:35
● Django Query Optimization (Soyoung Yoon) 
18th (Sun) 13:55 ~ 14:35
● Pickle & Custom Binary Serializer (Young Seok Kim) 
18th (Sun) 14:55 ~ 15:35
Talks from AITRICS

PyCon Korea 2019 REST API Document Generation

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