#34165: migrate management command does not respect database parameter for all
DB
calls
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Reporter: Vasanth | Owner: nobody
Type: Bug | Status: new
Component: Migrations | Version: 4.1
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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When invoking migrate with a database parameter, the migration runs
successfully. However, there seems to be a DB read request that runs after
the migration. This call does not respect the db param and invokes the db
router .
When naming the db as a parameter, all DB calls in the context of the
migrate command are expected to use the database specified.
I came across this as I am currently using a thread-local variable to get
the active DB with a custom DB router for a multi-tenant service .
**''Minimal example''**
{{{
from threading import local
from django.conf import settings
local_state = local()
class InvalidTenantException(Exception):
pass
class TenantSubdomainMiddleware:
def __init__(self, get_response):
self.get_response = get_response
def __call__(self, request):
## Get Subdomain
host = request.get_host().split(":")[0]
local_state.subdomain = (
# We assume single level of subdomain : app.service.com
# HOST_IP : used to for local dev.
host if host in settings.HOST_IP else host.split(".")[0]
)
response = self.get_response(request)
return response
class TenantDatabaseRouter:
def _default_db(self):
subdomain = getattr(local_state, "subdomain", None)
if subdomain is not None and subdomain in settings.TENANT_MAP:
db_name = settings.TENANT_MAP[local_state.subdomain]
return db_name
else:
raise InvalidTenantException()
def db_for_read(self, model, **hints):
return self._default_db()
def db_for_write(self, model, **hints):
return self._default_db()
def allow_relation(self, obj1, obj2, **hints):
return True
def allow_migrate(self, db, app_label, model_name=None, **hints):
return True
## settings.py
MIDDLEWARE = [
"utils.tenant_db_router.TenantSubdomainMiddleware",
"django.middleware.security.SecurityMiddleware",
...
]
TENANT_MAP = {"localhost":"default", "tenant_1":"default"}
DATABASE_ROUTERS = ["utils.tenant_db_router.TenantDatabaseRouter"]
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/34165>
Django <https://code.djangoproject.com/>
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