# Access prefetch\_related objects **URL:** \ **Category:** Using the ORM\ **Created:** [February 28, 2023, 8:58pm UTC](https://forum.djangoproject.com/t/access-prefetch-related-objects/19173 "2023-02-28T20:58:28Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![spinozagl](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/spinozagl/32/12450_2.png) [@spinozagl](https://forum.djangoproject.com/u/spinozagl)\ **Post date:** [February 28, 2023, 8:58pm UTC](https://forum.djangoproject.com/t/access-prefetch-related-objects/19173/1 "2023-02-28T20:58:28Z")
```auto latest_update = BillHistory.objects.filter( bill=OuterRef('id')).order_by('-occurred_datetime') user_bills = Bill.objects.only( "bill_number", "short_title").filter(session='2023-2024').filter( Q(users__archived=False) & Q(users__user=user)).annotate( priority=F('users __billuserpriority__ priority'), position=F('users __billuserposition__ position'), latest_update_on=Max('histories__occurred_datetime'), committee_names=Subquery( latest_update.values('committee_names__name')[:1]), latest_update_status=Subquery( latest_update.values('status')[:1])).prefetch_related( 'users __clients__ client', 'users __pillars__ pillar').order_by( Func(F('bill_number'), function='alphanum')) ``` prefetch\_related works wonders here. What is the more performant query to access the prefetched objects? At the moment, I am accessing a client object like so in the template: bill.users.all → users.clients.all → client. Although I am able to filter first by user and then by clients for that user, this is resulting in duplicate and similar queries. Thank you. ---
**Author:** ![jnns](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/jnns/32/950_2.png) [@jnns](https://forum.djangoproject.com/u/jnns)\ **Post date:** [March 1, 2023, 1:03pm UTC](https://forum.djangoproject.com/t/access-prefetch-related-objects/19173/2 "2023-03-01T13:03:03Z")
Which query is duplicated exactly? Did you try the [Prefetch](https://docs.djangoproject.com/en/4.1/ref/models/querysets/#django.db.models.Prefetch) object with its `to_attr=` option to specify an attribute on the QuerySet model to store the prefetched object in a list in? If you use `Prefetch(..., to_attr="clients")`, you can access them via `bill.clients` in your template. ```python # This is your code snippet formatted with Black (https://black.readthedocs.io) # This way it's easier for others to see what your queryset actually does. latest_update = BillHistory.objects.filter(bill=OuterRef("id")).order_by( "-occurred_datetime" ) user_bills = ( Bill.objects.only("bill_number", "short_title") .filter(session="2023-2024") .filter(Q(users__archived=False) & Q(users__user=user)) .annotate( priority=F("users __billuserpriority__ priority"), position=F("users __billuserposition__ position"), latest_update_on=Max("histories__occurred_datetime"), committee_names=Subquery(latest_update.values("committee_names__name")[:1]), latest_update_status=Subquery(latest_update.values("status")[:1]), ) .prefetch_related("users __clients__ client", "users __pillars__ pillar") .order_by(Func(F("bill_number"), function="alphanum")) ) ``` ---
**Author:** ![spinozagl](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/spinozagl/32/12450_2.png) [@spinozagl](https://forum.djangoproject.com/u/spinozagl)\ **Post date:** [March 1, 2023, 4:47pm UTC](https://forum.djangoproject.com/t/access-prefetch-related-objects/19173/3 "2023-03-01T16:47:48Z")
Thank you for your response. I use yapf for formatting. Black works well too. I have tried using Prefetch with the to\_attr attribute set. ```auto .prefetch_related(Prefetch("users__clients", queryset=BillUserClient.objects.filter(billuser=user), to_attr="bill_clients")) ``` I’d like to access clients attached to a bill by an authenticated user, in my template passing a Bill instance to the context. I’d like to do this without looping through all users and all clients. I am trying to work out why I can’t seem to use bill.bill\_clients to access the clients attached to the bill by a particular authenticated user using prefetch\_related with Prefetch. There are through-tables between Bill, User, and Client, without any explicit many-to-many field set in the Bill model or the Client model (see below) ```auto class BillUser(TimestampedModel): user = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='bills', on_delete=models.RESTRICT) bill = models.ForeignKey(Bill, related_name='users', on_delete=models.RESTRICT) archived = models.BooleanField("Archived", default=False) class Meta: # unique_together = ('user', 'bill') constraints = [ models.UniqueConstraint(fields=['user', 'bill'], name='bill_user_unique') ] indexes = [ models.Index(fields=['user', 'bill'], name='bill_user_idx'), models.Index(fields=['bill'], name='bill_user_bill_idx'), models.Index(fields=['user'], name='bill_user_user_idx'), models.Index(fields=['archived'], name='bill_user_archived_idx'), ] def __str__ (self): return f"{self.user} - {self.bill} - archived: {self.archived}" ``` ```auto class BillUserClient(TimestampedModel): """ Many-to-Many through table for BillUser and Client Models """ billuser = models.ForeignKey(BillUser, related_name='clients', on_delete=models.RESTRICT) client = models.ForeignKey(KslegbtrClient, related_name='billusers', on_delete=models.RESTRICT) class Meta: # unique_together = ('billuser', 'client') constraints = [ models.UniqueConstraint(fields=['billuser', 'client'], name='billuser_client_unique') ] ordering = ['client'] def __str__ (self): return f"{self.billuser} - {self.client.short_name}" ```