django filter when the some of the arguments are null

Question

I'm now using django filter to get the queryset I want,here is my code:

             students = Student.objects.filter(
                sales=current_user,
                nickname = form_data['nickname'],
                mobile = form_data['mobile'],
                gender = form_data['gender'],
                state = form_data['state'],
                source = form_data['source'],
                register_at = form_data['register_at'],
                importance = form_data['importance'],
                remaining = form_data['remaining'],
                level = form_data['level'],
                feature = form_data['feature'],
                company_name = form_data['company']
            ).order_by(register_order, remaining_order, level_order)

now the question is :some of my form data fields may be null, cause the forms are input by the user, and he/she can choose to just input some fields, I wonder if this code could work when some fields are null, if not, how to rewrite it to get the queryset based on the fields user inputs?

You should not use `form_data`, but use `form.cleaned_data` to get valid data. — Rohan, May 06 '13 at 09:40
Might be duplicate of http://stackoverflow.com/questions/310732/in-django-how-does-one-filter-a-queryset-with-dynamic-field-lookups — Rohan, May 06 '13 at 09:43
well I didn't paste the form_data = some_form(request.GET)， I‘m doing this query in the get_queryset in a ListView — Roger Liu, May 06 '13 at 09:45
form = some_form(request.GET), form_data = form.cleaned_data ,sorry — Roger Liu, May 06 '13 at 09:54
you could filter `form_data`, excluding all keys that have `None` valu, and then pass the dictionary to `filter()` like `filter(**clean_form_data)`. — Bibhas Debnath, May 06 '13 at 10:07

score 3 · Accepted Answer · answered May 06 '13 at 10:40

The logic could be like this:

# start with this
students = Student.objects.filter(sales=current_user)

value = form.cleaned_data.get('nickname', None)
if value is not None:
    students = students.filter(nickname=value)

# etc, etc ...

# end with that
students = students.order_by(register_order, remaining_order, level_order)

But of course, this would be ugly considering how many fields you have. Instead, you could have something like this:

students = Student.objects.filter(sales=current_user)
    
fields = ['nickname', 'mobile', 'gender', ....]
for field in fields:
    value = form.cleaned_data.get(field, None)
    if value is not None:
        students = students.filter(**{field: value})
    
students = students.order_by(register_order, remaining_order, level_order)

Or, using all fields of the form:

students = Student.objects.filter(sales=current_user)
    
for key, value in form.cleaned_data.items():
    if value is not None:
        students = students.filter(**{key: value})
    
students = students.order_by(register_order, remaining_order, level_order)

Note that we're testing if value is not None instead of just if value, this is to allow '0' values to pass the test.

Thanks for your answer, I chose the 3rd way:) – Roger Liu May 07 '13 at 01:40 — Roger Liu, May 07 '13 at 01:40

django filter when the some of the arguments are null

1 Answers1