환경설정

가상환경 생성 및 활성화

(Linux)
python3 -m venv env
source env/bin/activate

(Windows)
python3 -m venv env
env/Scripts/activate

모듈 설치

pip install django
pip install djangorestframework
pip install pygments # for 코드 하이라이팅 

시작하기

프로젝트 생성

django-admin startproject tutorial
cd tutorial

앱 생성

python manage.py startapp snippets

앱 추가

# tutorial/settings.py
INSTALLED_APPS = [
    ...
    'rest_framework',
    'snippets.apps.SnippetsConfig',
]

모델 생성

# snippets/models.py
from django.db import models
from pygments.lexers import get_all_lexers
from pygments.styles import get_all_styles

LEXERS = [item for item in get_all_lexers() if item[1]]
LANGUAGE_CHOICES = sorted([(item[1][0], item[0]) for item in LEXERS])
STYLE_CHOICES = sorted([(item, item) for item in get_all_styles()])


class Snippet(models.Model):
    created = models.DateTimeField(auto_now_add=True)
    title = models.CharField(max_length=100, blank=True, default='')
    code = models.TextField()
    linenos = models.BooleanField(default=False)
    language = models.CharField(choices=LANGUAGE_CHOICES, default='python', max_length=100)
    style = models.CharField(choices=STYLE_CHOICES, default='friendly', max_length=100)

    class Meta:
        ordering = ['created']

python manage.py makemigrations snippets
python manage.py migrate

Serializer 생성

• Snippet 인스턴스를 json으로 직렬화, 역 직렬화
  - '변환'이라고 이해하면 될 듯하다
• Form과 매우 유사

# snippets/serializers.py
from rest_framework import serializers
from snippets.models import Snippet, LANGUAGE_CHOICES, STYLE_CHOICES


class SnippetSerializer(serializers.Serializer):
    id = serializers.IntegerField(read_only=True)
    title = serializers.CharField(required=False, allow_blank=True, max_length=100)
    code = serializers.CharField(style={'base_template': 'textarea.html'})
    linenos = serializers.BooleanField(required=False)
    language = serializers.ChoiceField(choices=LANGUAGE_CHOICES, default='python')
    style = serializers.ChoiceField(choices=STYLE_CHOICES, default='friendly')

    def create(self, validated_data):
        return Snippet.objects.create(**validated_data)

    def update(self, instance, validated_data):
        instance.title = validated_data.get('title', instance.title)
        instance.code = validated_data.get('code', instance.code)
        instance.linenos = validated_data.get('linenos', instance.linenos)
        instance.language = validated_data.get('language', instance.language)
        instance.style = validated_data.get('style', instance.style)
        instance.save()
        return instance

create(), update() 함수

• serializer.save()를 호출할 때 인스턴스가 어떻게 생성되고 수정되는지 정의

필드 및 validation flag

• Form과 매우 유사
• required, max_length 등
• 필드 flag는 또한 특정 환경에서 serializer가 어떻게 보여지는지 설정할 수 있다.

style={'base_template': 'textarea.html'}

• 예를 들어 HTML로 rendering할 때 이 코드는

widget=widgets.Textarea

• Form에서 이 코드와 유사하다
• ModelSerializer 클래스를 사용할 수 있다.

사용하기

shell 실행

python manage.py shell

인스턴스 생성

# shell
from snippets.models import Snippet
from snippets.serializers import SnippetSerializer
from rest_framework.renderers import JSONRenderer
from rest_framework.parsers import JSONParser

snippet = Snippet(code='foo = "bar"\n')
snippet.save()

snippet = Snippet(code='print("hello, world")\n')
snippet.save()

serialize

# shell
serializer = SnippetSerializer(snippet)
serializer.data
# {'id': 2, 'title': '', 'code': 'print("hello, world")\n', 'linenos': False, 'language': 'python', 'style': 'friendly'}

json으로 변환

# shell
content = JSONRenderer().render(serializer.data)
content
# b'{"id": 2, "title": "", "code": "print(\\"hello, world\\")\\n", "linenos": false, "language": "python", "style": "friendly"}'

deserialization

import io

stream = io.BytesIO(content)
data = JSONParser().parse(stream)

native datatype to object instance

serializer = SnippetSerializer(data=data)
serializer.is_valid()
# True
serializer.validated_data
# OrderedDict([('title', ''), ('code', 'print("hello, world")\n'), ('linenos', False), ('language', 'python'), ('style', 'friendly')])
serializer.save()
# <Snippet: Snippet object>

추가

• 모델 인스턴스가 아닌 쿼리셋도 직렬화 가능
• many=True 플래그 추가

serializer = SnippetSerializer(Snippet.objects.all(), many=True)
serializer.data
# [OrderedDict([('id', 1), ('title', ''), ('code', 'foo = "bar"\n'), ('linenos', False), ('language', 'python'), ('style', 'friendly')]), OrderedDict([('id', 2), ('title', ''), ('code', 'print("hello, world")\n'), ('linenos', False), ('language', 'python'), ('style', 'friendly')]), OrderedDict([('id', 3), ('title', ''), ('code', 'print("hello, world")'), ('linenos', False), ('language', 'python'), ('style', 'friendly')])]

정리

1. 인스턴스 to json (직렬화)
2. json to 인스턴스 (역직렬화)

ModelSerializer 사용하기

• Form과 ModelForm의 관계와 유사

serializers 수정

class SnippetSerializer(serializers.ModelSerializer):
    class Meta:
        model = Snippet
        fields = ['id', 'title', 'code', 'linenos', 'language', 'style']

확인하기

from snippets.serializers import SnippetSerializer
serializer = SnippetSerializer()
print(repr(serializer))
# SnippetSerializer():
#    id = IntegerField(label='ID', read_only=True)
#    title = CharField(allow_blank=True, max_length=100, required=False)
#    code = CharField(style={'base_template': 'textarea.html'})
#    linenos = BooleanField(required=False)
#    language = ChoiceField(choices=[('Clipper', 'FoxPro'), ('Cucumber', 'Gherkin'), ...
#    style = ChoiceField(choices=[('autumn', 'autumn'), ('borland', 'borland'), ...

뷰 작성하기

Read, Create

• GET : 기존 스니펫 보여주기
• POST : 새 스니펫 생성하기

from django.http import HttpResponse, JsonResponse
from django.views.decorators.csrf import csrf_exempt
from rest_framework.parsers import JSONParser
from snippets.models import Snippet
from snippets.serializers import SnippetSerializer


@csrf_exempt
def snippet_list(request):
    """
    List all code snippets, or create a new snippet.
    """
    if request.method == 'GET':
        snippets = Snippet.objects.all()
        serializer = SnippetSerializer(snippets, many=True)
        return JsonResponse(serializer.data, safe=False)

    elif request.method == 'POST':
        data = JSONParser().parse(request)
        serializer = SnippetSerializer(data=data)
        if serializer.is_valid():
            serializer.save()
            return JsonResponse(serializer.data, status=201)
        return JsonResponse(serializer.errors, status=400)

Read, Update, Delete

@csrf_exempt
def snippet_detail(request, pk):
    """
    Retrieve, update or delete a code snippet.
    """
    try:
        snippet = Snippet.objects.get(pk=pk)
    except Snippet.DoesNotExist:
        return HttpResponse(status=404)

    if request.method == 'GET':
        serializer = SnippetSerializer(snippet)
        return JsonResponse(serializer.data)

    elif request.method == 'PUT':
        data = JSONParser().parse(request)
        serializer = SnippetSerializer(snippet, data=data)
        if serializer.is_valid():
            serializer.save()
            return JsonResponse(serializer.data)
        return JsonResponse(serializer.errors, status=400)

    elif request.method == 'DELETE':
        snippet.delete()
        return HttpResponse(status=204)

url 연결

# snippets/urls.py
from django.urls import path
from snippets import views

urlpatterns = [
    path('snippets/', views.snippet_list),
    path('snippets/<int:pk>/', views.snippet_detail),
]

# tutorial/urls.py
from django.urls import path, include

urlpatterns = [
    path('', include('snippets.urls')),
]

주의

• 우리가 잘못된 json을 보내거나, 뷰가 지원하지 않는 메소드로 요청이 왔을 때 500에러가 발생할 것임

테스트하기

서버 실행

python manage.py runserver

Validating models...

0 errors found
Django version 1.11, using settings 'tutorial.settings'
Development server is running at http://127.0.0.1:8000/
Quit the server with CONTROL-C.

httpie 설치

• curl도 가능
• 파이썬으로 작성된 사용자 친화적인 http client

pip install httpie

테스트

http http://127.0.0.1:8000/snippets/

HTTP/1.1 200 OK
...
[
  {
    "id": 1,
    "title": "",
    "code": "foo = \"bar\"\n",
    "linenos": false,
    "language": "python",
    "style": "friendly"
  },
  {
    "id": 2,
    "title": "",
    "code": "print(\"hello, world\")\n",
    "linenos": false,
    "language": "python",
    "style": "friendly"
  }
]

• 또는

http http://127.0.0.1:8000/snippets/2/

HTTP/1.1 200 OK
...
{
  "id": 2,
  "title": "",
  "code": "print(\"hello, world\")\n",
  "linenos": false,
  "language": "python",
  "style": "friendly"
}

링크

https://www.django-rest-framework.org/tutorial/1-serialization/#testing-our-first-attempt-at-a-web-api