Django Rest FrameWork （一）序列化

建立一个新的 Django 开发环境：

1. 使用 virtualenv 创建一个新的虚拟环境。

mkdir ~/env/
virtualenv ~/env/tutorial
source ~/env/tutorial/bin/activate

2. 接着，在虚拟环境内部安装我们所需要的包

pip install django
pip install djangorestframework
pip install pygments

3. 创建一个 django 项目

cd ~ 
django-admin.py startproject tutorial
cd tutorial
python manage.py startapp tutorial

4. 为了方便这里使用 sqlite3 作为数据库，并且编辑 tutorial/setting.py 文件。

        DATABASES = {
        'default':{
            'ENGINE': 'django.db.backends.sqlite3',
            'NAME': 'tmp.db',
            'USER': '',
            'PASSWORD': '',
            'HOST': '',
            'PORT': '',
        }
    }

5. 同时，我们需要将 snippets app 和 rest_framewokr app 加载到 INSTALLED_APPS。

INSTALLED_APPS = [
        ...
        'rest_framework',
        'snippets',
		]

6. 需要在 项目根目录下的 urls.py 增加如下配置：

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

---

创建一个 models

1. 创建一个简单的 Snippet model. 修改 snippets 目录下 models.py 文件

from django.db import models
from pygments.lexers import get_all_lexers
from pygments.styles import get_all_styles

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

class Snippet(models.Model):
        created = models.DateTimeField(auto_now_add=True)
        title = models.CharField(max_length=100, 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',)

接着，在数据库中生成 snippet 表

python manage.py makemigrations
python manage.py migrate

---

建立一个 Serializer 类

1. 在 snippet 文件夹中创建一个 serializers.py 文件并且添加如下代码：

from django.forms import widgets
from rest_framework import serializers
from snippets import models

class SnippetSerializer(serializers.Serializer):
        pk = serializers.Field()  # Note: `Field` is an untyped read-only field.
        title = serializers.CharField(required=False,
                                      max_length=100)
        code = serializers.CharField(widget=widgets.Textarea,
                                     max_length=100000)
        linenos = serializers.BooleanField(required=False)
        language = serializers.ChoiceField(choices=models.LANGUAGE_CHOICES,
                                           default='python')
        style = serializers.ChoiceField(choices=models.STYLE_CHOICES,
                                        default='friendly')

        def restore_object(self, attrs, instance=None):
            """
            Create or update a new snippet instance.
            """
            if instance:
                # Update existing instance
                instance.title = attrs['title']
                instance.code = attrs['code']
                instance.linenos = attrs['linenos']
                instance.language = attrs['language']
                instance.style = attrs['style']
                return instance

            # Create new instance
            return models.Snippet(**attrs)

2. 在 Django shell 中应用 Serializers

 $ python manage.py shell

导入所需要的包

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

将数据序列化成一个实例

    serializer = SnippetSerializer(snippet)
    serializer.data
    # {'pk': 1, 'title': u'', 'code': u'print "hello, world"\n', 'linenos': False, 'language': u'python', 'style': u'friendly'}

最后将实例转换成 json 格式

content = JSONRenderer().render(serializer.data)

content
# '{"pk": 1, "title": "", "code": "print \\"hello, world\\"\\n", "linenos": false, "language": "python", "style": "friendly"}'