Get last record in a queryset
DjangoDjango QuerysetDjango Problem Overview
How can I retrieve the last record in a certain queryset?
Django Solutions
Solution 1 - Django
> latest(field_name=None)
returns the latest object in the table, by date, using the field_name provided as the date field.
>
> This example returns the latest Entry in the table, according to the
> pub_date
field:
>
> Entry.objects.latest('pub_date')
Solution 2 - Django
EDIT : You now have to use Entry.objects.latest('pub_date')
You could simply do something like this, using reverse()
:
queryset.reverse()[0]
Also, beware this warning from the Django documentation:
> ... note that reverse()
should
> generally only be called on a QuerySet
> which has a defined ordering (e.g.,
> when querying against a model which
> defines a default ordering, or when
> using order_by()
). If no such ordering
> is defined for a given QuerySet
,
> calling reverse()
on it has no real
> effect (the ordering was undefined
> prior to calling reverse()
, and will
> remain undefined afterward).
Solution 3 - Django
The simplest way to do it is:
books.objects.all().last()
You also use this to get the first entry like so:
books.objects.all().first()
Solution 4 - Django
To get First object:
ModelName.objects.first()
To get last objects:
ModelName.objects.last()
You can use filter
ModelName.objects.filter(name='simple').first()
This works for me.
Solution 5 - Django
Django >= 1.6
Added QuerySet methods first() and last() which are convenience methods returning the first or last object matching the filters. Returns None if there are no objects matching.
Solution 6 - Django
When the queryset is already exhausted, you may do this to avoid another db hint -
last = queryset[len(queryset) - 1] if queryset else None
Don't use try...except...
.
Django doesn't throw IndexError
in this case.
It throws AssertionError
or ProgrammingError
(when you run python with -O option)
Solution 7 - Django
You can use Model.objects.last()
or Model.objects.first()
.
If no ordering
is defined then the queryset is ordered based on the primary key. If you want ordering behaviour queryset then you can refer to the last two points.
If you are thinking to do this, Model.objects.all().last()
to retrieve last and Model.objects.all().first()
to retrieve first element in a queryset or using filters
without a second thought. Then see some caveats below.
The important part to note here is that if you haven't included any ordering
in your model the data can be in any order and you will have a random last or first element which was not expected.
Eg. Let's say you have a model named Model1
which has 2 columns id
and item_count
with 10 rows having id 1 to 10.[There's no ordering defined]
If you fetch Model.objects.all().last() like this, You can get any element from the list of 10 elements. Yes, It is random as there is no default ordering.
So what can be done?
- You can define
ordering
based on any field or fields on your model. It has performance issues as well, Please check that also. Ref: Here - OR you can use
order_by
while fetching. Like this:Model.objects.order_by('item_count').last()
Solution 8 - Django
If using django 1.6 and up, its much easier now as the new api been introduced -
Model.object.earliest()
It will give latest() with reverse direction.
p.s. - I know its old question, I posting as if going forward someone land on this question, they get to know this new feature and not end up using old method.
Solution 9 - Django
In a Django template I had to do something like this to get it to work with a reverse queryset:
thread.forumpost_set.all.last
Hope this helps someone looking around on this topic.
Solution 10 - Django
MyModel.objects.order_by('-id')[:1]
Solution 11 - Django
If you use ids with your models, this is the way to go to get the latest one from a qs.
obj = Foo.objects.latest('id')
Solution 12 - Django
The simplest way, without having to worry about the current ordering, is to convert the QuerySet to a list so that you can use Python's normal negative indexing. Like so:
list(User.objects.all())[-1]