在Python的框架中为MySQL实现restful接口的教程

最近在做游戏服务分层的时候，一直想把mysql的访问独立成一个单独的服务DBGate，原因如下:

1. 请求收拢到DBGate，可以使DBGate变为无状态的，方便横向扩展
2. 当请求量或者存储量变大时，mysql需要做分库分表，DBGate可以内部直接处理，外界无感知
3. 通过restful限制对数据请求的形式，仅支持简单的get/post/patch/put 进行增删改查，并不支持复杂查询。这个也是和游戏业务的特性有关，如果网站等需要复杂查询的业务，对此并不适合
4. DBGate使用多进程模式，方便控制与mysql之间的链接数，进行mysql访问量阀值保护
5. 方便在DBGate上进行访问量统计，慢查询统计、权限控制等等一系列逻辑
6. 目前是使用python，以后要使用其他语言进行mysql操作时，只要进行标准的http请求即可，不会出现不兼容的情况

当然坏处也是有的：

1. 首当其冲就是单次请求的响应时间变长，毕竟中间加了一层服务，并且还是http格式
2. 部署上比原来复杂了一些，很多对mysql直接操作的思维需要进行转变，一开始可能会有些不适

不过总的来说，还是利大于弊，所以最终还是决定搭建DBGate

当然，我们不可能去手工挨个写每个库表对应的restful服务，值得庆幸的是django和flask都提供了对应的解决方案，我们一个个介绍.
Flask

参考链接: flask-restless

flask-restless使用方法比较简单，我直接贴一下代码即可:

# -*- coding: utf-8 -*-

import datetime
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_restless import APIManager

app = Flask(__name__)
db = SQLAlchemy(app)
restless = APIManager(app, flask_sqlalchemy_db=db)

class User(db.Model):
    """
    user
    """

id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(255), unique=True, nullable=False)
    password = db.Column(db.String(255), nullable=False)
    create_time = db.Column(db.DateTime, nullable=False, default=datetime.datetime.utcnow)
    login_time = db.Column(db.DateTime)

restless.create_api(User, methods=['GET', 'POST', 'DELETE', 'PATCH', 'PUT'], results_per_page=100)

db.create_all()

if __name__ == '__main__':
    app.run(port=25000)
 
# -*- coding: utf-8 -*-
 
import datetime
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_restless import APIManager
 
 
app = Flask(__name__)
db = SQLAlchemy(app)
restless = APIManager(app, flask_sqlalchemy_db=db)
 
 
class User(db.Model):
    """
    user
    """
 
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(255), unique=True, nullable=False)
    password = db.Column(db.String(255), nullable=False)
    create_time = db.Column(db.DateTime, nullable=False, default=datetime.datetime.utcnow)
    login_time = db.Column(db.DateTime)
 
 
restless.create_api(User, methods=['GET', 'POST', 'DELETE', 'PATCH', 'PUT'], results_per_page=100)
 
db.create_all()
 
if __name__ == '__main__':
    app.run(port=25000)

其对应的restful操作如下:

获取用户列表:   GET /user
添加用户:       POST /user
获取单个用户:   GET /user/1
覆盖单个用户:   PUT /user/1
修改单个用户:   PATCH /user/1

获取用户列表:   GET /user
添加用户:       POST /user
获取单个用户:   GET /user/1
覆盖单个用户:   PUT /user/1
修改单个用户:   PATCH /user/1

注意:

• 在http请求中，记得加入header: Content-Type: application/json
• flask-restless中，PUT和PATCH一样，都是传入什么字段，只修改什么字段，不会完全覆盖

Django

参考链接: Django REST framework

Django用起来要更复杂一些，也因为django版自带了一个可视化的操作页面，如下:

1. 在settings中添加:

REST_FRAMEWORK = {
  # Use hyperlinked styles by default.
  # Only used if the `serializer_class` attribute is not set on a view.
  'DEFAULT_MODEL_SERIALIZER_CLASS':
    'rest_framework.serializers.HyperlinkedModelSerializer',

  # Use Django's standard `django.contrib.auth` permissions,
  # or allow read-only access for unauthenticated users.
  'DEFAULT_PERMISSION_CLASSES': [
    #'rest_framework.permissions.DjangoModelPermissionsOrAnonReadOnly',
    'rest_framework.permissions.IsAdminUser',
  ]
}

REST_FRAMEWORK = {
  # Use hyperlinked styles by default.
  # Only used if the `serializer_class` attribute is not set on a view.
  'DEFAULT_MODEL_SERIALIZER_CLASS':
    'rest_framework.serializers.HyperlinkedModelSerializer',

  # Use Django's standard `django.contrib.auth` permissions,
  # or allow read-only access for unauthenticated users.
  'DEFAULT_PERMISSION_CLASSES': [
    #'rest_framework.permissions.DjangoModelPermissionsOrAnonReadOnly',
    'rest_framework.permissions.IsAdminUser',
  ]
}

2. 通过startapp建立一个app: demo
3. 修改demo的models:

class User(models.Model):
  # key是保留字
  password = models.IntegerField()
  nick = models.CharField(max_length=255)
  create_time = models.DateTimeField(default=datetime.datetime.now)

class User(models.Model):
  # key是保留字
  password = models.IntegerField()
  nick = models.CharField(max_length=255)
  create_time = models.DateTimeField(default=datetime.datetime.now)

4. 在demo下新建serializers.py

from rest_framework import serializersfrom models import User

class UserSerializer(serializers.ModelSerializer):
  class Meta:
    model = User

from rest_framework import serializers
from models import User

class UserSerializer(serializers.ModelSerializer):
  class Meta:
    model = User

5. 在demo下修改views.py

from django.shortcuts import render
from rest_framework import viewsets

from serializers import UserSerializer
from models import User

class UserViewSet(viewsets.ModelViewSet):
  queryset = User.objects.all()
  serializer_class = UserSerializer

from django.shortcuts import render
from rest_framework import viewsets

from serializers import UserSerializer
from models import User

class UserViewSet(viewsets.ModelViewSet):
  queryset = User.objects.all()
  serializer_class = UserSerializer

6. 在demo下新建urls.py

import os.path
from django.conf.urls import patterns, include, url
from django.conf.urls.static import static
from django.conf import settings
import views

from rest_framework import routers

appname = os.path.basename(os.path.dirname(os.path.abspath(__file__)))

router = routers.DefaultRouter()
router.register('users', views.UserViewSet, appname)

urlpatterns = patterns('',
            url(r'^', include(router.urls)),
)

import os.path
from django.conf.urls import patterns, include, url
from django.conf.urls.static import static
from django.conf import settings
import views

from rest_framework import routers

appname = os.path.basename(os.path.dirname(os.path.abspath(__file__)))

router = routers.DefaultRouter()
router.register('users', views.UserViewSet, appname)

urlpatterns = patterns('',
            url(r'^', include(router.urls)),
)

7. 在mysite.urls下include demo.urls和rest_framework.urls

urlpatterns = patterns('',
  url(r'^demo/', include('demo.urls')),
  url(r'^admin/', include(admin.site.urls)),
  url(r'^api-auth/', include('rest_framework.urls', namespace='rest_framework'))
)

urlpatterns = patterns('',
  url(r'^demo/', include('demo.urls')),
  url(r'^admin/', include(admin.site.urls)),
  url(r'^api-auth/', include('rest_framework.urls', namespace='rest_framework'))
)

8. 执行初始化数据操作:

python manage.py syncdb

python manage.py syncdb

之后访问: http://127.0.0.1:8000/demo 即可看到如下界面了:

对应的测试代码如下:

import json
import requests
from urlparse import urljoin

BASE_URL = 'http://127.0.0.1:16500/'
AUTH = ('admin', 'admin')

def test_get_user_list():
  rsp = requests.get(urljoin(BASE_URL, '/demo/users/'), auth=AUTH, headers={
    'Accept': 'application/json'
  })
  assert rsp.ok

def test_post_user_list():
  json_data = dict(
    password=0,
    nick='oo',
    create_time='2014-03-3T03:3:3'
  )
  rsp = requests.post(urljoin(BASE_URL, '/demo/users/'), auth=AUTH, headers={
    'Accept': 'application/json',
    'Content-Type': 'application/json',
  }, data=json.dumps(json_data))
  assert rsp.ok

def test_get_user():
  rsp = requests.get(urljoin(BASE_URL, '/demo/users/1'), auth=AUTH, headers={
    'Accept': 'application/json',
    'Content-Type': 'application/json',
  })
  assert rsp.ok

def test_put_user():
  json_data = dict(
    password=100,
    nick='xx',
    create_time='2014-03-3T03:3:3'
  )
  # 注意最后的 /
  rsp = requests.put(urljoin(BASE_URL, '/demo/users/1/'), auth=AUTH, headers={
    'Accept': 'application/json',
    'Content-Type': 'application/json',
    }, data=json.dumps(json_data),
  )
  assert rsp.ok, rsp.status_code

Django REST framework 是严格区分PUT和PATCH的，这一点和flask-restless 不一样，需要注意。

OK，就这样。