">", "<", ">=" and "<=" don't work with "filter()" in Django

Question

With = below, I could filter persons by age :

qs = Person.objects.filter(age = 20)
                             # ↑ Here

But with > , < , >= and <= below, I couldn't filter persons by age :

qs = Person.objects.filter(age > 20)
                             # ↑ Here

qs = Person.objects.filter(age < 20)
                             # ↑ Here

qs = Person.objects.filter(age >= 20)
                             # ↑↑ Here

qs = Person.objects.filter(age <= 20)
                             # ↑↑ Here

Then, I got the error below:

NameError: name 'age' is not defined

How can I do greater than(>) , greater than or equal to(>=) , less than(<) and less than or equal to(>=) with filter() in Django?

Answer 1

Less than or equal:

User.objects.filter(userprofile__level__lte=0)

Greater than or equal:

User.objects.filter(userprofile__level__gte=0)

Likewise, lt for less than and gt for greater than. You can find them all in the documentation .

Answer 2

The 1st answer works like a charm, to briefly explain it

You just put the field you want to compare then the double underscore and

gte    means >=
lte     means >=
gt      means >
lt       means <

The "level" in the first answer was supposedly a joint field name with userprofile from the question, it is not necessarily a key word

Answer 3

Put __gt suffix for " G reater T han" to the field name age :

Person.objects.filter(age__gt=20)
                    #    ↑↑↑↑ 
                    # age > 20

Put__gte suffix for " G reater T han or E qual to" to the field name age :

Person.objects.filter(age__gte=20)
                    #    ↑↑↑↑↑ 
                    # age >= 20

Put __lt suffix for " L ess T han" to the field name age :

Person.objects.filter(age__lt=20)
                    #    ↑↑↑↑ 
                    # age < 20

Put__lte suffix for " L ess T han or E qual to" to the field name age :

Person.objects.filter(age__lte=20)
                    #    ↑↑↑↑↑ 
                    # age <= 20