| showard | 09096d8 | 2008-07-07 23:20:49 +0000 | [diff] [blame] | 1 | from django.db import connection as django_connection |
| 2 | from django.conf import settings |
| 3 | from django.dispatch import dispatcher |
| 4 | from django.core import signals |
| 5 | |
| 6 | class ReadOnlyConnection(object): |
| 7 | """ |
| 8 | This class constructs a new connection to the DB using the read-only |
| 9 | credentials from settings. It reaches into some internals of |
| 10 | django.db.connection which are undocumented as far as I know, but I believe |
| 11 | it works across many, if not all, of the backends. |
| 12 | """ |
| 13 | def __init__(self): |
| 14 | self._connection = None |
| 15 | |
| 16 | |
| 17 | def _open_connection(self): |
| 18 | if self._connection is not None: |
| 19 | return |
| 20 | self._save_django_state() |
| 21 | self._connection = self._get_readonly_connection() |
| 22 | self._restore_django_state() |
| 23 | |
| 24 | |
| 25 | def _save_django_state(self): |
| 26 | self._old_connection = django_connection.connection |
| 27 | self._old_username = settings.DATABASE_USER |
| 28 | self._old_password = settings.DATABASE_PASSWORD |
| 29 | |
| 30 | |
| 31 | def _restore_django_state(self): |
| 32 | django_connection.connection = self._old_connection |
| 33 | settings.DATABASE_USER = self._old_username |
| 34 | settings.DATABASE_PASSWORD = self._old_password |
| 35 | |
| 36 | |
| 37 | def _get_readonly_connection(self): |
| 38 | settings.DATABASE_USER = settings.DATABASE_READONLY_USER |
| 39 | settings.DATABASE_PASSWORD = settings.DATABASE_READONLY_PASSWORD |
| 40 | django_connection.connection = None |
| 41 | # cursor() causes a new connection to be created |
| 42 | cursor = django_connection.cursor() |
| 43 | assert django_connection.connection is not None |
| 44 | return django_connection.connection |
| 45 | |
| 46 | |
| 47 | def set_django_connection(self): |
| 48 | assert (django_connection.connection != self._connection or |
| 49 | self._connection is None) |
| 50 | self._open_connection() |
| 51 | self._old_connection = django_connection.connection |
| 52 | django_connection.connection = self._connection |
| 53 | |
| 54 | |
| 55 | def unset_django_connection(self): |
| 56 | assert self._connection is not None |
| 57 | assert django_connection.connection == self._connection |
| 58 | django_connection.connection = self._old_connection |
| 59 | |
| 60 | |
| 61 | def cursor(self): |
| 62 | self._open_connection() |
| 63 | return self._connection.cursor() |
| 64 | |
| 65 | |
| 66 | def close(self): |
| 67 | if self._connection is not None: |
| 68 | assert django_connection != self._connection |
| 69 | self._connection.close() |
| 70 | self._connection = None |
| 71 | |
| 72 | |
| 73 | connection = ReadOnlyConnection() |
| 74 | # close any open connection when request finishes |
| 75 | dispatcher.connect(connection.close, signal=signals.request_finished) |