How do I do a not equal in Django queryset filtering?
PythonDjangoDjango ModelsDjango QuerysetPython Problem Overview
In Django model QuerySets, I see that there is a __gt
and __lt
for comparative values, but is there a __ne
or !=
(not equals)? I want to filter out using a not equals. For example, for
Model:
bool a;
int x;
I want to do
results = Model.objects.exclude(a=True, x!=5)
The !=
is not correct syntax. I also tried __ne
.
I ended up using:
results = Model.objects.exclude(a=True, x__lt=5).exclude(a=True, x__gt=5)
Python Solutions
Solution 1 - Python
You can use Q objects for this. They can be negated with the ~
operator and combined much like normal Python expressions:
from myapp.models import Entry
from django.db.models import Q
Entry.objects.filter(~Q(id=3))
will return all entries except the one(s) with 3
as their ID:
[<Entry: Entry object>, <Entry: Entry object>, <Entry: Entry object>, ...]
Solution 2 - Python
Your query appears to have a double negative, you want to exclude all rows where x
is not 5, so in other words you want to include all rows where x
is 5. I believe this will do the trick:
results = Model.objects.filter(x=5).exclude(a=True)
To answer your specific question, there is no "not equal to" field lookup but that's probably because Django has both filter
and exclude
methods available so you can always just switch the logic around to get the desired result.
Solution 3 - Python
the field=value
syntax in queries is a shorthand for field__exact=value
. That is to say that Django puts query operators on query fields in the identifiers. Django supports the following operators:
exact
iexact
contains
icontains
in
gt
gte
lt
lte
startswith
istartswith
endswith
iendswith
range
date
year
iso_year
month
day
week
week_day
iso_week_day
quarter
time
hour
minute
second
isnull
regex
iregex
I'm sure by combining these with the Q objects as Dave Vogt suggests and using filter()
or exclude()
as Jason Baker suggests you'll get exactly what you need for just about any possible query.
Solution 4 - Python
There are three options:
-
results = Model.objects.exclude(a=True).filter(x=5)
-
Use
Q()
objects and the~
operatorfrom django.db.models import Q object_list = QuerySet.filter(~Q(a=True), x=5)
-
Register a custom lookup function
from django.db.models import Lookup from django.db.models import Field @Field.register_lookup class NotEqual(Lookup): lookup_name = 'ne' def as_sql(self, compiler, connection): lhs, lhs_params = self.process_lhs(compiler, connection) rhs, rhs_params = self.process_rhs(compiler, connection) params = lhs_params + rhs_params return '%s <> %s' % (lhs, rhs), params
Which can the be used as usual:
results = Model.objects.exclude(a=True, x__ne=5)
Solution 5 - Python
It's easy to create a custom lookup, there's an __ne
lookup example in Django's official documentation.
You need to create the lookup itself first:
from django.db.models import Lookup
class NotEqual(Lookup):
lookup_name = 'ne'
def as_sql(self, compiler, connection):
lhs, lhs_params = self.process_lhs(compiler, connection)
rhs, rhs_params = self.process_rhs(compiler, connection)
params = lhs_params + rhs_params
return '%s <> %s' % (lhs, rhs), params
Then you need to register it:
from django.db.models import Field
Field.register_lookup(NotEqual)
And now you can use the __ne
lookup in your queries like this:
results = Model.objects.exclude(a=True, x__ne=5)
Solution 6 - Python
While you can filter Models with =
, __gt
, __gte
, __lt
, __lte
, you cannot use ne
or !=
. However, you can achieve better filtering using the Q object.
You can avoid chaining QuerySet.filter()
and QuerySet.exclude()
, and use this:
from django.db.models import Q
object_list = QuerySet.filter(~Q(field='not wanted'), field='wanted')
Solution 7 - Python
exclude()
Pending design decision. Meanwhile, use The Django issue tracker has the remarkable entry #5763, titled "Queryset doesn't have a "not equal" filter operator". It is remarkable because (as of April 2016) it was "opened 9 years ago" (in the Django stone age), "closed 4 years ago", and "last changed 5 months ago".
Read through the discussion, it is interesting.
Basically, some people argue __ne
should be added
while others say exclude()
is clearer and hence __ne
should not be added.
(I agree with the former, because the latter argument is
roughly equivalent to saying Python should not have !=
because
it has ==
and not
already...)
Solution 8 - Python
Using exclude and filter
results = Model.objects.filter(x=5).exclude(a=true)
Solution 9 - Python
You should use filter
and exclude
like this
results = Model.objects.exclude(a=true).filter(x=5)
Solution 10 - Python
Django-model-values (disclosure: author) provides an implementation of the NotEqual lookup, as in this answer. It also provides syntactic support for it:
from model_values import F
Model.objects.exclude(F.x != 5, a=True)
Solution 11 - Python
This will give your desired result.
from django.db.models import Q
results = Model.objects.exclude(Q(a=True) & ~Q(x=5))
for not equal you can use ~
on an equal query. obviously, Q
can be used to reach the equal query.
Solution 12 - Python
The last bit of code will exclude all objects where x!=5 and a is True. Try this:
results = Model.objects.filter(a=False, x=5)
Remember, the = sign in the above line is assigning False to the parameter a and the number 5 to the parameter x. It's not checking for equality. Thus, there isn't really any way to use the != symbol in a query call.
Solution 13 - Python
What you are looking for are all objects that have either a=false
or x=5
. In Django, |
serves as OR
operator between querysets:
results = Model.objects.filter(a=false)|Model.objects.filter(x=5)
Solution 14 - Python
results = Model.objects.filter(a = True).exclude(x = 5)Generetes this sql:
select * from tablex where a != 0 and x !=5The sql depends on how your True/False field is represented, and the database engine. The django code is all you need though.
Solution 15 - Python
Watch out for lots of incorrect answers to this question!
Gerard's logic is correct, though it will return a list rather than a queryset (which might not matter).
If you need a queryset, use Q:
from django.db.models import Q
results = Model.objects.filter(Q(a=false) | Q(x=5))
Solution 16 - Python
If we need to exclude/negate based on the sub queryset we can use,
When a conditional expression returns a boolean value, it is possible to use it directly in filters. Here non_unique_account_type
returns a boolean value. But, still, we can use it in the filter.
>>> non_unique_account_type = Client.objects.filter(
... account_type=OuterRef('account_type'),
... ).exclude(pk=OuterRef('pk')).values('pk')
>>> Client.objects.filter(~Exists(non_unique_account_type))
In the SQL terms, it evaluates to:
SELECT * FROM client c0
WHERE NOT EXISTS (
SELECT c1.id
FROM client c1
WHERE c1.account_type = c0.account_type AND NOT c1.id = c0.id
)
Solution 17 - Python
This should work
results = Model.objects.filter(x=5).exclude(a=True)