#23273: MigrationRecorder does not obey db_router allow_migrate rules
----------------------------+--------------------------------------
Reporter: froomzy | Owner: nobody
Type: Bug | Status: new
Component: Migrations | Version: 1.7-rc-2
Severity: Normal | Resolution:
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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Comment (by froomzy):
@jarshwah: I don't think it is the router. Mainly because the router is
not called at this point. Which is what I believe is the bug.
@akaariai: I agree that there are similarities. Surely I should be able to
manage which connections I actually run migrations against. That seems to
be what the db_router is trying to do.
I thought that something like the following would solve our problem:
{{{
from django.db import router
.
.
.
def ensure_schema(self):
"""
Ensures the table exists and has the correct schema.
"""
# If the table's there, that's fine - we've never changed its
schema
# in the codebase.
if self.Migration._meta.db_table in
self.connection.introspection.get_table_list(self.connection.cursor()):
return
# Make the table
# Change below, similar to how allowed_to_migrate in
django/db/migrations/operations/base.py works
if router.allow_migrate(self.connection, self.Migration):
with self.connection.schema_editor() as editor:
editor.create_model(self.Migration)
}}}
But this means that changes to applied_migrations, record_applied, and
record_unapplied need to be made, so that it doesn't try to write to a
none existent table.
For us this is not an urgent issue, as we have appropriate permissions to
those connections that are not our core connection. But I do have a
concern for any time that we are using a true read-only connection, where
we do not have the CREATE TABLE permission. Because this code, as it
exists, will blow up in this situation. I tested that with a read-only
connection in our db setup, and got an insufficient permissions error.
Thanks,
Dylan
--
Ticket URL: <https://code.djangoproject.com/ticket/23273#comment:3>
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