本文讲述在一个 django project 中使用多个数据库的方法, 多个数据库的联用 以及多数据库时数据导入导出的方法。
直接给出一种简单的方法吧,想了解更多的到官方教程,点击此处
代码文件下载:project_name.zip(2017年05月01日更新)
1. 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:
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# 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.mysql'
,
'NAME'
:
'dbname1'
,
'USER'
:
'your_db_user_name'
,
'PASSWORD'
:
'yourpassword'
,
"HOST"
:
"localhost"
,
},
'db2'
: {
'ENGINE'
:
'django.db.backends.mysql'
,
'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:
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# -*- 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
# for Django 1.4 - Django 1.6
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
# Django 1.7 - Django 1.11
def
allow_migrate(
self
, db, app_label, model_name
=
None
,
*
*
hints):
print
db, app_label, model_name, hints
if
db
in
DATABASE_MAPPING.values():
return
DATABASE_MAPPING.get(app_label)
=
=
db
elif
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。
2.使用指定的数据库来执行操作
在查询的语句后面用 using(dbname) 来指定要操作的数据库即可
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# 查询
YourModel.objects.using(
'db1'
).
all
()
或者 YourModel.objects.using(
'db2'
).
all
()
# 保存 或 删除
user_obj.save(using
=
'new_users'
)
user_obj.delete(using
=
'legacy_users'
)
|