按照建议，我发布了该案例的完整答案，该问题可能暗示。
假设您有一个外部数据库表，您决定将其作为 Django 模型进行访问，因此将其描述为非托管模型 (Meta: managed = False)。
稍后您需要能够在代码中创建它，例如使用本地数据库进行一些测试。显然，Django 不会对非托管模型进行迁移，因此不会在您的测试数据库中创建它。
这可以使用 Django API 解决，而无需使用原始 SQL - SchemaEditor。请参阅下面更完整的示例，但作为一个简短的答案，您可以像这样使用它：
from django.db import connections
with connections['db_to_create_a_table_in'].schema_editor() as schema_editor:
schema_editor.create_model(YourUnmanagedModelClass)
一个实际的例子：
# your_app/models/your_model.py
from django.db import models
class IntegrationView(models.Model):
"""A read-only model to access a view in some external DB."""
class Meta:
managed = False
db_table = 'integration_view'
name = models.CharField(
db_column='object_name',
max_length=255,
primaty_key=True,
verbose_name='Object Name',
)
some_value = models.CharField(
db_column='some_object_value',
max_length=255,
blank=True,
null=True,
verbose_name='Some Object Value',
)
# Depending on the situation it might be a good idea to redefine
# some methods as a NOOP as a safety-net.
# Note, that it's not completely safe this way, but might help with some
# silly mistakes in user code
def save(self, *args, **kwargs):
"""Preventing data modification."""
pass
def delete(self, *args, **kwargs):
"""Preventing data deletion."""
pass
现在，假设您需要能够通过 Django 创建此模型，例如进行一些测试。
# your_app/tests/some_test.py
# This will allow to access the `SchemaEditor` for the DB
from django.db import connections
from django.test import TestCase
from your_app.models.your_model import IntegrationView
class SomeLogicTestCase(TestCase):
"""Tests some logic, that uses `IntegrationView`."""
# Since it is assumed, that the `IntegrationView` is read-only for the
# the case being described it's a good idea to put setup logic in class
# setup fixture, that will run only once for the whole test case
@classmethod
def setUpClass(cls):
"""Prepares `IntegrationView` mock data for the test case."""
# This is the actual part, that will create the table in the DB
# for the unmanaged model (Any model in fact, but managed models will
# have their tables created already by the Django testing framework)
# Note: Here we're able to choose which DB, defined in your settings,
# will be used to create the table
with connections['external_db'].schema_editor() as schema_editor:
schema_editor.create_model(IntegrationView)
# That's all you need, after the execution of this statements
# a DB table for `IntegrationView` will be created in the DB
# defined as `external_db`.
# Now suppose we need to add some mock data...
# Again, if we consider the table to be read-only, the data can be
# defined here, otherwise it's better to do it in `setUp()` method.
# Remember `IntegrationView.save()` is overridden as a NOOP, so simple
# calls to `IntegrationView.save()` or `IntegrationView.objects.create()`
# won't do anything, so we need to "Improvise. Adapt. Overcome."
# One way is to use the `save()` method of the base class,
# but provide the instance of our class
integration_view = IntegrationView(
name='Biggus Dickus',
some_value='Something really important.',
)
super(IntegrationView, integration_view).save(using='external_db')
# Another one is to use the `bulk_create()`, which doesn't use
# `save()` internally, and in fact is a better solution
# if we're creating many records
IntegrationView.objects.using('external_db').bulk_create([
IntegrationView(
name='Sillius Soddus',
some_value='Something important',
),
IntegrationView(
name='Naughtius Maximus',
some_value='Whatever',
),
])
# Don't forget to clean after
@classmethod
def tearDownClass(cls):
with connections['external_db'].schema_editor() as schema_editor:
schema_editor.delete_model(IntegrationView)
def test_some_logic_using_data_from_integration_view(self):
self.assertTrue(IntegrationView.objects.using('external_db').filter(
name='Biggus Dickus',
))
为了使示例更完整...由于我们使用多个 DB（default 和 external_db），Django 将尝试在这两个数据库上运行迁移以进行测试，到目前为止，DB 中没有选项设置以防止这种情况。所以我们必须使用自定义的 DB 路由器进行测试。
# your_app/tests/base.py
class PreventMigrationsDBRouter:
"""DB router to prevent migrations for specific DBs during tests."""
_NO_MIGRATION_DBS = {'external_db', }
def allow_migrate(self, db, app_label, model_name=None, **hints):
"""Actually disallows migrations for specific DBs."""
return db not in self._NO_MIGRATION_DBS
以及所描述案例的测试设置文件示例：
# settings/test.py
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.oracle',
'NAME': 'db_name',
'USER': 'username',
'HOST': 'localhost',
'PASSWORD': 'password',
'PORT': '1521',
},
# For production here we would have settings to connect to the external DB,
# but for testing purposes we could get by with an SQLite DB
'external_db': {
'ENGINE': 'django.db.backends.sqlite3',
},
}
# Not necessary to use a router in production config, since if the DB
# is unspecified explicitly for some action Django will use the `default` DB
DATABASE_ROUTERS = ['your_app.tests.base.PreventMigrationsDBRouter', ]
希望这个详细的新 Django 用户友好示例能够帮助某人并节省他们的时间。