Django Multi-database application

1. settings.py:

   
   

   DATABASES = {

   ' Default ': {

   ' ENGINE ': ' Django.db.backends.mysql ', # Add ' postgresql_psycopg2 ', ' MySQL ', ' sqlite3 ' or ' Oracle '.

   ' NAME ': ' Test ', # Or path to database file if using Sqlite3.

   ' USER ': ' Test ', # not used with Sqlite3.

   ' PASSWORD ': ' Test ', # not used with Sqlite3.

   ' HOST ': ', # Set to empty string for localhost. Not used with Sqlite3.

   ' PORT ': ' 3306 ', # Set to empty string for default. Not used with Sqlite3.

   },

   ' User ': {

   ' ENGINE ': ' Django.db.backends.mysql ', # Add ' postgresql_psycopg2 ', ' MySQL ', ' sqlite3 ' or ' Oracle '.

   ' NAME ': ' UserDB ', # Or path to database file if using Sqlite3.

   ' User ': ' User ', # used with Sqlite3.

   ' PASSWORD ': ' User ', # used with Sqlite3.

   ' HOST ': ' 10.58.**.** ', # Set to empty string for localhost. Not used with Sqlite3.

   ' PORT ': ' 3306 ', # Set to empty string for default. Not used with Sqlite3.

   }

   }

   Database_routers = [' dbsettings.appdb ']
   

2. Implement your own DB routers, which determines which db each application uses

   dbsettings.py:

   
   

   Class Appdb (object):

   def db_for_read (self, model, **hints):

   #该方法定义读取时从哪一个数据库读取

   return Self.__app_router (model)

   def db_for_write (self, model, **hints):

   #该方法定义写入时从哪一个数据库读取, if read-write separation, can be additional configuration

   return Self.__app_router (model)

   def allow_relation (self, obj1, Obj2, **hints):

   #该方法用于判断传入的obj1和obj2是否允许关联, can be used for many-to-many and foreign keys

   #同一个应用同一个数据库

   if Obj1._meta.app_label = = Obj2._meta.app_label:

   Return True

   #User和Essay是允许关联的

   Elif Obj1._meta.app_label in (' Userapp ', ' Essayapp ') and

   #接上一行 Obj2._meta.app_label in (' Userapp ', ' Essayapp '):

   Return True

   def allow_syncdb (self, DB, model):

   #该方法定义数据库是否能和名为db的数据库同步

   return Self.__app_router (model) = = db

   #添加一个私有方法用来判断模型属于哪个应用 and return the database that should be used

   def __app_router (self, model):

   if Model._meta.app_label = = ' user ':

   Return ' UserDB '

   else:

   Return ' Default '

4. How to use

   User.objects.using (' user '). All ()

   Python manage.py syncdb--database=user

6. Custom sql:

8. 
   

From django.db Import connections

cursor = connections[' user '].cursor ()

Sql= "SELECT * User"

Cursor.execute (SQL)

rows = Cursor.fetchall ()

Return Render_to_response (' index.html ', locals ())

This article is from the "Seagrass" blog, please be sure to keep this source http://961911.blog.51cto.com/951911/1676221

Django Multi-database application