Django在多个数据库中复制表格

huangapple
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英文:

Django duplicate tables with multiple databases

问题

我有多个数据库，一个是sqlite，其他的是postgresql，都在同一个应用程序中使用。当我执行数据库迁移时，所有在models.py中定义的表都会在所有数据库中创建，包括sqlite数据库，或者如果我在allow_migrate函数中添加return False，则什么都不会发生。

如何阻止出现重复的表格？

这是我的代码：

settings.py

  1. DATABASE_ROUTERS = ['routers.router.sqlite_Router','routers.router.postgres_router_1','routers.router.postgres_router_2']
  3. DATABASES = {
  4.     'default': {},
  5.     'auth_db': {
  6.         'ENGINE': 'django.db.backends.sqlite3',
  7.         'NAME': BASE_DIR / 'db.sqlite3',
  8.     },
  9.     'postgres_db_1': {
  10.         'ENGINE': 'django.db.backends.postgresql',
  11.         'OPTIONS': {
  12.             'options': '-c search_path=test'
  13.         },
  14.         'NAME': 'test1',
  15.         'USER': 'postgres',
  16.         'PORT':'5432',
  17.         'PASSWORD': 'postgres',
  18.         'HOST':'localhost',
  19.     },
  20.     'postgres_db_2': {
  21.         'ENGINE': 'django.db.backends.postgresql',
  22.         'OPTIONS': {
  23.             'options': '-c search_path=test'
  24.         },
  25.         'NAME': 'test2',
  26.         'USER': 'postgres',
  27.         'PORT':'5432',
  28.         'PASSWORD': 'postgres',
  29.         'HOST':'localhost',
  30.     }
  31. }

router.py

  1. class sqlite_Router:
  2.     route_app_labels = {'auth', 'contenttypes','admin','sessions'}
  3.     database = 'auth_db'
  4.     # ...
  5.     def allow_migrate(self, db, app_label, model_name=None, **hints):
  6.         model = hints.get('model')
  7.         if model:
  8.             usedb = getattr(model._meta, 'database', None)
  9.             if app_label in self.route_app_labels and usedb == self.database:
  10.                 return db == self.database # True
  11.             # else: return False # <= I only get django_migrations, no other tables
  12.         return None
  14. class postgres_router_1:
  15.     route_app_labels = {'test'}
  16.     database = 'postgres_db_1'
  17.     # ...
  18.     def allow_migrate(self, db, app_label, model_name=None, **hints):
  19.         model = hints.get('model')
  20.         if model:
  21.             usedb = getattr(model._meta, 'database', None)
  22.             if app_label in self.route_app_labels and usedb == self.database:
  23.                 return db == self.database # True
  24.             # else: return False # <= I only get django_migrations, no other tables
  25.         return None
  27. class postgres_router_2:
  28.     route_app_labels = {'test'}
  29.     database = 'postgres_db_2'
  30.     # ...
  31.     def allow_migrate(self, db, app_label, model_name=None, **hints):
  32.         model = hints.get('model')
  33.         if model:
  34.             usedb = getattr(model._meta, 'database', None)
  35.             if app_label in this.route_app_labels and usedb == this.database:
  36.                 return db == this.database # True
  37.             # else: return False # <= I only get django_migrations, no other tables
  38.         return None

models.py

  1. from django.db import models
  2. models.options.DEFAULT_NAMES = models.options.DEFAULT_NAMES + ('database', )
  4. class postgres_one_test(models.Model):
  5.     postgres_test_one = models.CharField(unique=True, max_length=30)
  6.     def __str__(self):
  7.         return self.postgres_test_one
  8.     class Meta:
  9.         app_label = 'test'
  10.         database = 'postgres_db_1'
  12. class postgres_two_test(models.Model):
  13.     postgres_test_two = models.CharField(unique=True, max_length=30)
  14.     def __str__(self):
  15.         return self.postgres_test_two
  16.     class Meta:
  17.         app_label = 'test'
  18.         database = 'postgres_db_2'
  19. # ...

请注意，Meta类中的database属性指定了每个模型属于哪个数据库。在路由器中，您使用allow_migrate方法来控制哪些应用程序可以迁移到哪个数据库。根据您的配置，每个路由器只应用于特定的应用程序，并将其迁移到相应的数据库。确保您的路由器和模型的配置正确无误，这样您就可以避免重复创建表格。

英文:

I have multiple databases one is sqlite and the others in postgresql using one app, when i migrate bases 'using routers' all the tables in models.py gets created in all the bases including sqlite or nothing if i added return false to the allow_migrate function.

how to stop duplicate tables from happening ??

this is my code 'example'

settings.py

  1. DATABASE_ROUTERS = [&#39;routers.router.sqlite_Router&#39;,&#39;routers.router.postgres_router_1&#39;,&#39;routers.router.postgres_router_2&#39;]
  3. DATABASES = {
  4.     &#39;default&#39;: {},
  5.     &#39;auth_db&#39;: {
  6.         &#39;ENGINE&#39;: &#39;django.db.backends.sqlite3&#39;,
  7.         &#39;NAME&#39;: BASE_DIR / &#39;db.sqlite3&#39;,
  8.     },
  9.     &#39;postgres_db_1&#39;: {
  10.         &#39;ENGINE&#39;: &#39;django.db.backends.postgresql&#39;,
  11.         &#39;OPTIONS&#39;: {
  12.             &#39;options&#39;: &#39;-c search_path=test&#39;
  13.         },
  14.         &#39;NAME&#39;: &#39;test1&#39;,
  15.         &#39;USER&#39;: &#39;postgres&#39;,
  16.         &#39;PORT&#39;:&#39;5432&#39;,
  17.         &#39;PASSWORD&#39;: &#39;postgres&#39;,
  18.         &#39;HOST&#39;:&#39;localhost&#39;,
  19.     },
  20.     &#39;postgres_db_2&#39;: {
  21.         &#39;ENGINE&#39;: &#39;django.db.backends.postgresql&#39;,
  22.         &#39;OPTIONS&#39;: {
  23.             &#39;options&#39;: &#39;-c search_path=test&#39;
  24.         },
  25.         &#39;NAME&#39;: &#39;test2&#39;,
  26.         &#39;USER&#39;: &#39;postgres&#39;,
  27.         &#39;PORT&#39;:&#39;5432&#39;,
  28.         &#39;PASSWORD&#39;: &#39;postgres&#39;,
  29.         &#39;HOST&#39;:&#39;localhost&#39;,
  30.     }
  31. }

router.py

  1. class sqlite_Router:
  2.     route_app_labels = {&#39;auth&#39;, &#39;contenttypes&#39;,&#39;admin&#39;,&#39;sessions&#39;}
  3.     database = &#39;auth_db&#39;
  4.     ....
  5.     def allow_migrate(self, db, app_label, model_name=None, **hints):
  6.         model = hints.get(&#39;model&#39;)
  7.         if model:
  8.             usedb = getattr(model._meta, &#39;database&#39;, None)
  9.             if app_label in self.route_app_labels and usedb == self.database:
  10.                 return db == self.database # True
  11.             #else: return False # &lt;== i only get django_migrations, no other tables
  12.         return None
  14. class postgres_router_1:
  15.     route_app_labels = {&#39;test&#39;}
  16.     database = &#39;postgres_db_1&#39;
  17.     ....
  18.     def allow_migrate(self, db, app_label, model_name=None, **hints):
  19.         model = hints.get(&#39;model&#39;)
  20.         if model:
  21.             usedb = getattr(model._meta, &#39;database&#39;, None)
  22.             if app_label in self.route_app_labels and usedb == self.database:
  23.                 return db == self.database # True
  24.             #else: return False # &lt;== i only get django_migrations, no other tables
  25.         return None
  27. class postgres_router_2:
  28.     route_app_labels = {&#39;test&#39;}
  29.     database = &#39;postgres_db_2&#39;
  30.     ....
  31.     def allow_migrate(self, db, app_label, model_name=None, **hints):
  32.         model = hints.get(&#39;model&#39;)
  33.         if model:
  34.             usedb = getattr(model._meta, &#39;database&#39;, None)
  35.             if app_label in self.route_app_labels and usedb == self.database:
  36.                 return db == self.database # True
  37.             #else: return False # &lt;== i only get django_migrations, no other tables
  38.         return None

models.py

  1. from django.db import models
  2. models.options.DEFAULT_NAMES = models.options.DEFAULT_NAMES + (&#39;database&#39;, )
  3. class postgres_one_test(models.Model):
  4.     postgres_test_one = models.CharField(unique=True, max_length=30)
  5.     def __str__(self):
  6.         return self.postgres_test_one
  7.     class Meta:
  8.         app_label = &#39;test&#39;
  9.         database = &#39;postgres_db_1&#39;
  10. .... 
  13. class postgres_two_test(models.Model):
  14.     postgres_test_two = models.CharField(unique=True, max_length=30)
  15.     def __str__(self):
  16.         return self.postgres_test_two
  17.     class Meta:
  18.         app_label = &#39;test&#39;
  19.         database = &#39;postgres_db_2&#39;
  22. ...

答案1

得分: 0

找到了一个解决方案。

更改了django.db.models.options。

在DEFAULT_NAMES中添加了'database'。

在'class Options'的'init'中添加了'self.database = None'。

并将sqlite_router'django apps->allow_migrate'更改为默认值

  1. if app_label in self.route_app_labels:
  2.     return db == self.database
  3. return None

并从allow_migrate中删除'return False'。

还从models中删除了

  1. models.options.DEFAULT_NAMES = models.options.DEFAULT_NAMES + ('database', )

因为它不再需要。其余部分保持不变。

英文:

found A solution.

changed django.db.models.options

added 'database' in the DEFAULT_NAMES

and 'self.database = None' in the 'init' of 'class Options',

and the sqlite_router 'django apps->allow_migrate' to the default

  1. if app_label in self.route_app_labels:
  2.     return db == self.database
  3. return None

and removed the 'return False' from the allow_migrate.

also removed

  1. models.options.DEFAULT_NAMES = models.options.DEFAULT_NAMES + (&#39;database&#39;, )

from models as it's not needed.

everything else is the same

huangapple
  • 本文由 发表于 2023年3月4日 08:22:16
  • 转载请务必保留本文链接：https://go.coder-hub.com/75632881.html
  • database
  • django
  • python
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