Django项目配置连接多个数据库的方法记录

一个APP对应一个默认数据库，若连接其他数据库用".using()"

Author.objects.using('db02').all()

1、在项目settings中增加数据库配置

# settings.py
 
DATABASES = {
'default': {
 'ENGINE': 'django.db.backends.oracle',
 'NAME': 'orcl19c', 
 'USER': "username01",
 'PASSWORD': "password01",
 'HOST': "110.10.1.11",
 'PORT': 1511,
 },
'db_2': {
 'ENGINE': 'django.db.backends.oracle',
 'NAME': 'orcl19c', 
 'USER': "username02",
 'PASSWORD': "password02",
 'HOST': "120.20.2.22",
 'PORT': 1512,
 }
}
# 以下MyProject改成项目名，默认default不用修改
DATABASE_ROUTERS = ['MyProject.database_router.DatabaseAppsRouter']
DATABASE_APPS_MAPPING = {
'app01': 'default',
'app02': 'db_2',
}

2、在项目根目录下Myproject/Myproject 新建数据库路由文件database_router.py

直接复制以下代码，无需修改

from django.conf import settings
 
DATABASE_MAPPING = settings.DATABASE_APPS_MAPPINGclass 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
 
def allow_migrate(self, db, app_label, model=None, **hints):
"""
Make sure the auth app only appears in the 'auth_db'
database.
"""
if db in DATABASE_MAPPING.values():
return DATABASE_MAPPING.get(app_label) == db
elif app_label in DATABASE_MAPPING:
return False
return None

3、使用inspectdb反向生成各app的model类之后，配置model类对应要链接的数据库

反向生成models.py 命令：

python manage.py inspectdb --database db1 TableName1 > app01/models.py
 
python manage.py inspectdb --database db2 TableName2 > app02/models.py

# 编辑app01下的models.py:
class Names(models.Model): #该model使用default数据库
id=models.CharField(primary_key=True,max_length=100, blank=True, null=True)
name=models.CharField(max_length=32,primary_key=True,unique=True)class Meta:
#app_label = 'app01' #由于该model连接default数据库，所以在此无需指定
db_table = 'names'# 编辑app02下的models.py:
class Classnum(models.Model): #该model使用default数据库
id=models.CharField(primary_key=True,max_length=100, blank=True, null=True)
classnum=models.CharField(max_length=32,primary_key=True,unique=True)class Meta:
app_label = 'app02'
db_table = 'classnum'

4、同步数据库

# 同步default节点数据库，只运行不带 --database参数的命令，不对其他数据库进行同步
 
python manage.py makemigrations
 
python manage.py migrate
 
# 同步db02节点数据库：
 
python manage.py makemigrations
 
python manage.py migrate --database=db02

5、若要连接配置外的数据库

Author.objects.using('other').all()
my_object.save(using='legacy_users')
my_object.delete(using='legacy_users')

移动对象到另一个数据库时会发生主键冲突，可以使用obj.pk方法清除主键再保存对象

>>> p = Person(name='Fred')
>>> p.save(using='first')
>>> p.pk = None # Clear the primary key.
>>> p.save(using='second') # Write a 

总结