Putting the following code somewhere after settings.py is imported (a
new app called 'startup' in __init__.py, with 'startup' added first in
INSTALLED_APPS is a good place), will allow you to lock models to
databases via a manager's forced_using attribute. This definitely not
'the best way', as monkey patching is a little nasty. However, I'm not
sure this would be accepted as a patch (when formulated as such), and
this works for me, so i'm just sharing it for whoever needs it.
I haven't seen any bugs, so if you use it and find any let me know.
Thanks again to Alex for making the multidb branch.
-CB
------------------------------------
from django.db import models
def hijack_for_partitioning():
"""This class enables you to add a forced_using = 'db_name' to a
manager,
which will lock queries and saves for that model to that
particular db.
In addition, if this is /not/ specified on a custom manager, it
will lock every model to the 'default' db.
"""
_real_save = models.Model.save
def save(self, *args, **kwargs):
kwargs['using'] = type(self).objects.forced_using #Makes sure
instances are saved in the proper place
_real_save(self, *args, **kwargs)
models.Model.save = save
_real_get_query_set = models.Manager.get_query_set
def get_query_set(self):
qs = _real_get_query_set(self)
if hasattr(self, 'forced_using'):
qs = qs.using(self.forced_using)
qs._real_using = qs.using
qs.using = lambda new_using: qs._real_using(qs._db)
#Disable changing db with .using() - required because related manager
tries to set .using after we return the qs
return qs
models.Manager.get_query_set = get_query_set
models.Manager.forced_using = 'default'
models.Manager.use_for_related_fields = True
hijack_for_partitioning()
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