Separating the database read Django

1, the first is the configuration database

The settings.pyincrease configure multiple database files:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    },
    'db2': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db2.sqlite3'),   # 指定数据库名
    }
}

Use mysqlconfigurations:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'HOST': '127.0.0.1',
        'PORT': 3306,
        'USER': 'user',
        'PASSWORD': 'pd',
        'NAME': 'db_read'
    },
    'db2': {
        'ENGINE': 'django.db.backends.mysql',
        'HOST': '127.0.0.1',
        'PORT': 8306,
        'USER': 'root',
        'PASSWORD': 'pd',
        'NAME': 'db_write'
    }
}

2, perform database migration

python manage.py migrate   -- database db2  # 将default库中的表结构同步到db2

After the completion of the implementation of the above instructions, you will find, db2 library which will have our table

3, take a look at the case of read and write separation, django how to play

Manually separate read and write

In view function, which is specified by the library objects.using ( "library name") Use

from django.shortcuts import HttpResponse
from . import models 

def write(request):
    models.Products.objects.using('default').create(name='大猿', age=12)
    return HttpResponse('写入成功')


def read(request):
    obj = models.Products.objects.using('db2').filter(id=1).first()
    return HttpResponse(obj.name)

Automatic separate read and write

Rewrite create a py file, where we create a router.pyfile

class Router:
    # 读操作用default库，就return这个库名字符串
    def db_for_read(self,model,**kwargs):    # db_for_read固定写法,读操作自动匹配   # db_for_write固定写法,写操作自动匹配
        return 'default'
        
    # 读操作用db2库，就return这个库名字符串
    def db_for_write(self,model,**kwargs):   # db_for_write固定写法,写操作自动匹配
        return 'db2'

Also you need to settings.pyperform configuration file:

DATABASE_ROUTERS = ['app01.router.Router',] 
#写上面这个类的路径，我的是在app01应用文件夹下面的router.py文件中了

After the automatic setting operation does not need the use of library functions in the logical view ofusing

def dbtest(request):
    data = []
    # 向db2数据库中写入数据
    models.Class.objects.create(name='大猿',age=18)

    # 从db1中读取数据
    data = models.Class.objects.all()

    return render(request,'dbtest.html',{'data':data})

4, a multi-master program from

A master multi-slave of time, that is, when reading from multiple databases, we can do this: create a file or write function below the

import random
 
class Router:
    def db_for_read(self, model, **kwargs):
        return random.choices(['db1', 'db2', 'db3'])
        #多个库读的时候，可以简单的写个随机选择
 
    def db_for_write(self, model, **kwargs):
        return 'db'

In the settings.pysame configuration and the top file:

DATABASE_ROUTERS = ['app01.router.Router',] 
#写上面这个类的路径，我的是在app01应用文件夹下面的router.py文件中了

5, sub-library sub-table

When we need to make a different app operation of different databases, such as app01database operation db1, app02database operation db2, how should we do it, or create a separate file, worded as follows:

class Router:
    def db_for_read(self, model, **kwargs):
        if model._meta.app_label == 'app01':
            return 'db1'
        if model._meta.app_label == 'app02':
            return 'db2'
 
    def db_for_write(self, model, **kwargs):
       if model._meta.app_label == 'app01':
            return 'db1'
       if model._meta.app_label == 'app02':
            return 'db2'

# model._meta.app_label      获取当前函数所在app的app名称  

# 如果是类，需要将类名加上
# model.UserInfo._meta.app_label        获取该类所在app的app名称

In the settings.pyfile configuration:

DATABASE_ROUTERS = ['app01.router.Router',] 
#写上面这个类的路径，我的是在app01应用文件夹下面的router.py文件中了