# Django多数据库使用记录

2 min read
old_website

1.在setting.py文件中设置数据库引擎、数据库名字和数据库路由：

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    },
    "testmultidb_db1": {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'test_db1.sqlite3'),
    },
}


# use multi-database in django
# 这里如果写了下面这个数据库路由，那么在app文件夹下的views里就不用写using("哪个数据库")了，
# 如：models.TestInfo.objects.using("testmultidb_db1").create(aaa=username)
# 所以为了可读性，不建议写下面的数据库路由，app要使用其他数据库的话，可以直接写objects.using("哪个数据库")
DATABASE_ROUTERS = ['mysite.database_router.DatabaseAppsRouter']
DATABASE_APPS_MAPPING = {
    # example:
    # 'app_name':'database_name',
    'testmultidb': 'testmultidb_db1',
}

2.如果在setting.py里写了上面的那个数据库路由，则需要在mysite/mysite/文件夹内创建database_router.py，并粘贴如下代码：

# -*- 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) :
        if db in DATABASE_MAPPING.values() :
            return DATABASE_MAPPING.get(app_label) == db
        elif app_label in DATABASE_MAPPING :
            return False
        return None
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