Django 多数据库联用

摘要: Django 多数据库联用

每个app都可以单独设置一个数据库
settings.py中有数据库的相关设置，有一个默认的数据库 default,我们可以再加一些其它的，比如：

# Database
# https://docs.djangoproject.com/en/1.8/ref/settings/#databases DATABASES = {
'default': {
'ENGINE': 'django.db.backends.sqlite3',
'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
},
'db1': {
'ENGINE': 'django.db.backends.postgresql_psycopg2',
'NAME': 'dbname1',
'USER': 'your_db_user_name',
'PASSWORD': 'yourpassword',
"HOST": "localhost",
},
'db2': {
'ENGINE': 'django.db.backends.postgresql_psycopg2',
'NAME': 'dbname2',
'USER': 'your_db_user_name',
'PASSWORD': 'yourpassword',
"HOST": "localhost",
},
}

# use multi-database in django
# add by WeizhongTu
DATABASE_ROUTERS = ['project_name.database_router.DatabaseAppsRouter']
DATABASE_APPS_MAPPING = {
# example:
#'app_name':'database_name',
'app1': 'db1',
'app2': 'db2',
}

在project_name文件夹中存放 database_router.py 文件，内容如下：

# -*- coding: utf-8 -*-
from django.conf import settings

DATABASE_MAPPING = settings.DATABASE_APPS_MAPPING

class DatabaseAppsRouter(object):
"""
A router to control all database operations on models for different
databases.

In case an app is not set in settings.DATABASE_APPS_MAPPING, the router
will fallback to the `default` database.

Settings example:

DATABASE_APPS_MAPPING = {'app1': 'db1', 'app2': 'db2'}
"""

def db_for_read(self, model, **hints):
""""Point all read operations to the specific database."""
if model._meta.app_label in DATABASE_MAPPING:
return DATABASE_MAPPING[model._meta.app_label]
return None

def db_for_write(self, model, **hints):
"""Point all write operations to the specific database."""
if model._meta.app_label in DATABASE_MAPPING:
return DATABASE_MAPPING[model._meta.app_label]
return None

def allow_relation(self, obj1, obj2, **hints):
"""Allow any relation between apps that use the same database."""
db_obj1 = DATABASE_MAPPING.get(obj1._meta.app_label)
db_obj2 = DATABASE_MAPPING.get(obj2._meta.app_label)
if db_obj1 and db_obj2:
if db_obj1 == db_obj2:
return True
else:
return False
return None

def allow_syncdb(self, db, model):
"""Make sure that apps only appear in the related database."""

if db in DATABASE_MAPPING.values():
return DATABASE_MAPPING.get(model._meta.app_label) == db
elif model._meta.app_label in DATABASE_MAPPING:
return False
return None

这样就实现了指定的 app 使用指定的数据库了,当然你也可以多个sqlite3一起使用，相当于可以给每个app都可以单独设置一个数据库！如果不设置或者没有设置的app就会自动使用默认的数据库。