标签：logs lex read_only 创建 div stream 接下来 使用 instance
个人粗浅的理解，欢迎批评指正
什么是序列化？
后端任务无非对数据库的增查删改，操作数据库无非操作字段，序列化可以让我们轻松的对数据库增（serializer.create）改（serilaizer.update)的同时不用担心提交的key/value是否合法（serializer.is_valid）,并轻松的将dict 格式转为更通用的json格式（JSONRenderer）
什么是反序列化？
将json转为（JSONParser().parse(stream)）可序列化的dict（serializer(data=data)）
跟着教程走一波
先安装一下virtualenv
新建一个虚拟环境env
进入env虚拟环境
sudo apt-get install virtualenv virtualenv env source env/bin/activate
离开虚拟环境：deactivate
ps：如果使用pycharm IDE，在file-settings-Project：XXX-Project Interpreter,将项目解释器设置为虚拟环境中安装的python
在我们的虚拟环境中安装其他所需库
pip install django
pip install djangorestframework
pip install pygments # 用来高亮代码的库
创建项目，创建app
cd ~ django-admin.py startproject tutorial cd tutorial
python manage.py startapp snippets
记得settings.INSTALLED_APPS中添加刚才创建的app
INSTALLED_APPS = (
...
‘rest_framework‘,
‘snippets.apps.SnippetsConfig‘,
)
django 创建一个django模型
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‘,)
有没有菜鸡跟我一样才发现，原来从模型这里就可以限制字段的可选值（choices）
Meta元类中的ordering是指quarySet排序按’created‘字段来
django的orm
操作下数据库
python manage.py makemigrations snippets python manage.py migrate
重点到了，新建一个serializers.py 文件，并创建我们的序列化类
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
create和update是必须在子类中实现的方法，因为调用serializer.save()方法会用到他们
serializer类和django的model类很相似，可以在声明的时候限制字段的属性
接下来看看怎么使用序列化类
先打开django shell
python manage.py shell
然后创建两个数据
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()
接着：
1：序列化
serializer = SnippetSerializer(snippet) serializer.data
# {‘id‘: 2, ‘title‘: u‘‘, ‘code‘: u‘print "hello, world"\n‘, ‘linenos‘: False, ‘language‘: u‘python‘, ‘style‘: u‘friendly‘}2：转json
content = JSONRenderer().render(serializer.data)
content
# ‘{"id": 2, "title": "", "code": "print \\"hello, world\\"\\n", "linenos": false, "language": "python", "style": "friendly"}‘
3：转dict
from django.utils.six import BytesIO stream = BytesIO(content) data = JSONParser().parse(stream)
4：反序列化
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>
5：支持序列化多个数据
serializer = SnippetSerializer(Snippet.objects.all(), many=True) serializer.data # [OrderedDict([(‘id‘, 1), (‘title‘, u‘‘), (‘code‘, u‘foo = "bar"\n‘), (‘linenos‘, False), (‘language‘, ‘python‘), (‘style‘, ‘friendly‘)]), OrderedDict([(‘id‘, 2), (‘title‘, u‘‘), (‘code‘, u‘print "hello, world"\n‘), (‘linenos‘, False), (‘language‘, ‘python‘), (‘style‘, ‘friendly‘)]), OrderedDict([(‘id‘, 3), (‘title‘, u‘‘), (‘code‘, u‘print "hello, world"‘), (‘linenos‘, False), (‘language‘, ‘python‘), (‘style‘, ‘friendly‘)])]
看到这里感觉序列化就是将form对象转为dict格式，将quaryset转为OrderedDict
下节学习一下，正真更通用的ModelSerializers
参考资料：http://www.django-rest-framework.org/tutorial/1-serialization/#tutorial-1-serialization
[Django rest-framework] 1-Serialization
标签：logs lex read_only 创建 div stream 接下来 使用 instance
原文地址：http://www.cnblogs.com/lazySmeagol/p/7251634.html
