Django REST framework(序列化)

准备工作

一丶配置虚拟环境

1.安装虚拟包:pip install virtualenv 

2.创建一个用于虚拟环境的目录,并进入到目录下

3.执行 python -m venv 虚拟环境名

4.执行 virtualenv 虚拟环境名

5.在目录下激活虚拟环境  

windos下:source envScriptsactivate

linux下:source env/bin/activate

6.停止虚拟环境 deactivate指令或者关闭终端

二丶用于代码高亮显示pip install pygments

开始

一丶创建一个项目

1.新建一个项目目录,在目录中创建一个Django项目

cd 项目目标目录
django-admin.py startproject 项目名
cd 项目目录下

2.创建一个Django应用

python manage.py startapp snippets

3.将rest_framework和新建的应用注册到settings.py的INSTALLED_APPS中

INSTALLED_APPS = (
    ...
    'rest_framework',
    'snippets.apps.SnippetsConfig',
)

二丶编辑模型层

1.编辑模型层文件

应用下的models.py文件

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',)

2.迁移数据

项目根目录下
python manage.py makemigrations 应用名
python manage.py migrate

三丶序列化

1.应用下建立serializers.py文件

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):
        """
        Create and return a new `Snippet` instance, given the validated data.
        """
        return Snippet.objects.create(**validated_data)

    def update(self, instance, validated_data):
        """
        Update and return an existing `Snippet` instance, given the 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

四丶使用序列化器

一丶序列化

1.进入python shell:python manage.py 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"
')
snippet.save()

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

2.查看实例化的数据

serializer = SnippetSerializer(snippet)
serializer.data

# {'id': 2, 'title': u'', 'code': u'print "hello, world"
', 'linenos': False, 'language': u'python', 'style': u'friendly'}

3.转换为json数据

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

二丶反序列化

1.解析字符串为python原生的数据类型

from django.utils.six import BytesIO

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

2.将原生数据类型变为对象实例

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

3.序列化querysets实例,将many=True参数加入序列化器

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

五丶使用ModelSerializers

REST framework包括Serializer类和ModelSerializer类,这样可以使代码更加的整洁.

ModelSerializer就像是Django的表单,不会有特别的功能但是是序列化的一个快捷方式.

1.找到应用下的serializers.py文件,替换代码

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

2.查看序列化器的所有字段

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'), ('RobotFramework', 'RobotFramework'), ('abap', 'ABAP'), ('ada', 'Ada')...
#    style = ChoiceField(choices=[('autumn', 'autumn'), ('borland', 'borland'), ('bw', 'bw'), ('colorful', 'colorful')...

六丶编写序列化试图

1.编辑应用下的views.py文件

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

2.加入以下方法

@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)

3.上述代码的升级版,用于增删改查数据

@csrf_exempt #跨越csrf令牌,进行POST请求
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)

4.url设置

创建应用的urls.py文件

from django.conf.urls import url
from snippets import views

urlpatterns = [
    url(r'^snippets/$', views.snippet_list),
    url(r'^snippets/(?P<pk>[0-9]+)/$', views.snippet_detail),
]

项目的urls.py文件

from django.conf.urls import url, include

urlpatterns = [
    url(r'^', include('snippets.urls')),
]

七丶测试Web API

1.运行Django服务:python manage.py runserver

2.安装httpie:pip install httpie,这是一个http客户端用python编写对客户非常友好

3.得到所有的数据列表

http http://127.0.0.1:8000/snippets/

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

4.通过id得到列表

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

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

5.也可以通过浏览器来访问Django项目