使用 2 个数据库的 Django 迁移?
Django migration with 2 DBs?
我有数据库 db1
和 db2
。两个数据库的模式应该使用相同的迁移脚本创建。
Django 文档提到了 DATABASE_ROUTERS and RunPython,但到目前为止我没能成功。函数被调用,但从函数调用时 migrations.CreateModel()
没有影响:未创建 table。
迁移脚本:
# 0001_initial.py
def forwards(apps, schema_editor):
if schema_editor.connection.alias == 'db1':
print('This line is called!')
migrations.CreateModel(
name='MyModel',
fields=[
('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
# ...
]
)
class Migration(migrations.Migration):
initial = True
dependencies = [
migrations.swappable_dependency(settings.AUTH_USER_MODEL),
]
operations = [
migrations.RunPython(forwards, hints={'target_db': 'db1'}),
]
路由器:
DatabaseRouter:
# ...
def allow_migrate(self, db, app_label, model_name=None, **hints):
if 'target_db' in hints:
return db == hints['target_db']
return True
命令:
python manage.py migrate --database=db1
有什么想法吗?提前致谢!
migrations.CreateModel
不会在实例化时在数据库中创建模型。它应该出现在 operations
列表中,然后迁移系统将使用它来创建模型。此外,您无论如何都不应该手动编写此迁移!只需将模型的代码写在 models.py
:
class MyModel(models.Model):
# Your fields, etc.
接下来因为你的问题问的是如何控制哪个模型迁移到哪个数据库。这些任务应该在 Database router 中完成,特别是在 allow_migrate
方法中。您可以检查为 db
、app_label
和 model_name
return 传递的值是否应将模型迁移到那里。例如:
class MyRouter:
def db_for_read(self, model, **hints):
...
def db_for_write(self, model, **hints):
...
def allow_relation(self, obj1, obj2, **hints):
...
def allow_migrate(self, db, app_label, model_name=None, **hints):
# Suppose I want to migrate all models from the app 'some_app' to 'db1' only.
if app_label in ['some_app']:
return db == 'db1'
# Suppose I want to migrate 'MyModel' to 'db2' only.
if model_name == 'mymodel': # 'mymodel' is lowercase 'MyModel'
return db == 'db2'
return None
我有数据库 db1
和 db2
。两个数据库的模式应该使用相同的迁移脚本创建。
Django 文档提到了 DATABASE_ROUTERS and RunPython,但到目前为止我没能成功。函数被调用,但从函数调用时 migrations.CreateModel()
没有影响:未创建 table。
迁移脚本:
# 0001_initial.py
def forwards(apps, schema_editor):
if schema_editor.connection.alias == 'db1':
print('This line is called!')
migrations.CreateModel(
name='MyModel',
fields=[
('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
# ...
]
)
class Migration(migrations.Migration):
initial = True
dependencies = [
migrations.swappable_dependency(settings.AUTH_USER_MODEL),
]
operations = [
migrations.RunPython(forwards, hints={'target_db': 'db1'}),
]
路由器:
DatabaseRouter:
# ...
def allow_migrate(self, db, app_label, model_name=None, **hints):
if 'target_db' in hints:
return db == hints['target_db']
return True
命令:
python manage.py migrate --database=db1
有什么想法吗?提前致谢!
migrations.CreateModel
不会在实例化时在数据库中创建模型。它应该出现在 operations
列表中,然后迁移系统将使用它来创建模型。此外,您无论如何都不应该手动编写此迁移!只需将模型的代码写在 models.py
:
class MyModel(models.Model):
# Your fields, etc.
接下来因为你的问题问的是如何控制哪个模型迁移到哪个数据库。这些任务应该在 Database router 中完成,特别是在 allow_migrate
方法中。您可以检查为 db
、app_label
和 model_name
return 传递的值是否应将模型迁移到那里。例如:
class MyRouter:
def db_for_read(self, model, **hints):
...
def db_for_write(self, model, **hints):
...
def allow_relation(self, obj1, obj2, **hints):
...
def allow_migrate(self, db, app_label, model_name=None, **hints):
# Suppose I want to migrate all models from the app 'some_app' to 'db1' only.
if app_label in ['some_app']:
return db == 'db1'
# Suppose I want to migrate 'MyModel' to 'db2' only.
if model_name == 'mymodel': # 'mymodel' is lowercase 'MyModel'
return db == 'db2'
return None