1.准备工作
首先,需要安装依赖包有:django、djangorestframework、pygments,这里通过pip命令直接安装,至于环境的配置问题,这里就不再进行赘述了,安装命令如下:
pip install django //本文基于django1.11版本来做
pip install djangorestframework
pip install pygments //实现代码的高亮2.新建一个名字tutorial的项目
django-admin startproject tutorial3.创建一个APP,名字叫snippets
//执行startapp命令来创建应用
python manage.py startapp snippets
//编辑tutorial/settings.py文件,将snippets和rest_framework加入到INSTALLED_APPS当中
INSTALLED_APPS = {
...
'snippets',
'rest_framework'
}4.创建一个snippets model
//在snippets/models.py中,写入以下代码:
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',)5.执行数据库迁移命令
python manage.py makemigrations snippets
python manage.py migrate6.创建一个序列化类(SnippetSerializer)
#这个类的功能和Django中的forms有点类似
//在snippets下,新建一个serializers.py文件
//在snippets/serializers.py中,写入以下代码:
from rest_framework import serializers
from snippets.models import Snippet, LANGUAGE_CHOICES, STYLE_CHOICES
class SnippetSerializer(serializers.Serializer):
"""
序列化器类的第一部分定义了序列化/反序列化的字段
create()和update()方法定义了在调用serializer.save()时如何创建和修改完整的实例。
"""
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):
"""
给定经过验证的数据,创建并返回一个新的"Snippet"实例
"""
return Snippet.objects.create(**validated_data)
def update(self, instance, validated_data):
"""
根据提供的验证过的数据更新和返回一个已经存在的`Snippet`实例
"""
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 instance7.启动Django shell
//启动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
#实例化Snippet这个类,增加相应的值并作保存
snippet = Snippet(code='foo = "bar"\n')
snippet.save()
snippet = Snippet(code='print("hello, world")\n')
snippet.save()8.序列化与反序列化
##执行结果:{'id': 2, 'title': '', 'code': 'print("hello, world")\n', 'linenos': False, 'language': 'python', 'style': 'friendly'}
#将实例snippet转换为Python原生数据类型,为了完成这个序列化的过程,需将返回的serializer.data转换为JSON格式
content = JSONRenderer().render(serializer.data)
content
##执行结果: b'{"id": 2, "title": "", "code": "print(\\"hello, world\\")\\n", "linenos": false, "language": "python", "style": "friendly"}'
#反序列化(还原序列化)的过程是类似的
#首先引入io模块,因为content是bytes类型的数据,所以这里调用BytesIO()这个方法,将这个流(stream)转换为Python原生数据类型
import io
stream = io.BytesIO(content)
data = JSONParser().parse(stream)
data9.将Python原生数据类型转为实例对象
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>10.序列化查询结果集
#上面在序列化的过程中,传的是Snippet对象,其实还可以传querysets对象
#只需要加入"many=True"即可
serializer = SnippetSerializer(Snippet.objects.all(), many=True)
serializer.data
##结果为: [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')])]11.使用ModelSerializer类
#在snippets/serializers.py中,将SnippetSerializer类替换为以下内容
class SnippetSerializer(serializers.ModelSerializer):
class Meta:
model = Snippet
fields = ('id', 'title', 'code', 'linenos', 'language', 'style')
#运行python manage.py shell,写下以下代码:
#通过打印实例的属性(representation)来查看所有字段
from snippets.serializers import SnippetSerializer
serializer = SnippetSerializer()
print(repr(serializer))需要注意的是,ModelSerializer类没有做什么特别的事情,它只是一个创建序列化类的捷径:1.实现一组自动确定的字段 2.默认简单地实现create()和update()这两个方法
12.使用Serializer来编写Django的视图
#首先导入如下包
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
#加上@csrf_exempt代表这个视图不需要csrf令牌也能访问
#创建一个根视图函数,用来列出所有现有的snippet或创建一个新的snippet
def snippet_list(request):
"""
列出所有的code snippets,或创建一个新的snippet
"""
if request.method == "GET":
snipppets = Snippet.objects.all()
serializer = SnippetSerializer(snipppets,many=True)
#将数据类型转为正常的实例的对象,通过data属性输出出来
return JsonResponse(serializer.data,safe=False)
elif request.method == "POST":
#对传过来的request做处理(假设这里传过来的是json格式的请求)
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)
@csrf_exempt
def snippet_detail(request,pk):
"""
获取,更新或删除一个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(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)13.编写url路径
#首先,先在snippets下创建一个urls.py文件,写入以下代码:
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),
]
#接着,在tutorial/urls.py中,写入以下代码:
from django.conf.urls import url,include
urlpatterns = [
url(r'^admin/', admin.site.urls),
url(r'^',include('snippets.urls'))
]14.测试API
#首先,安装一个依赖包,名字叫httpie,httpie是用Python编写的用户友好的http客户端
pip install httpie
#接着,使用python manage.py runserver 命令来启动Django
#在网址中输入:http://127.0.0.1:8000/snippets/,可获取所有数据
#输入http://127.0.0.1:8000/snippets/2/,可获取指定的数据
#这样,最开始的第一步就完成啦,完结撒花先嘿嘿嘿~
















