[Fixed]-Django filtering based on optional parameters

by

9👍

✅

You may want to look into Q objects. Briefly, the Q lets you use OR statements in your queries. From the aforelinked page:

Polls.objects.filter(
    Q(question__startswith='Who') | Q(question__startswith='What')
)

This will pull questions starting with "Who" OR "What".

👤eykanal

23👍

What you actually can do

from django.db.models import Q

q = Q()
if param_1 != 'all':
    q &= Q(param_1__name=param_1)

if param_2 != 'all':
    q &= Q(param_2__name=param_2)

class_var = ClassName.objects.filter(q)

OR

q = {}
if param_1 != 'all':
    q.update({'param_1__name': param_1})

if param_2 != 'all':
    q.update({'param_2__name': param_2})

class_var = ClassName.objects.filter(**q)
👤Basalex

3👍

Use Q objects an make an list of queries.

q=[]
if param_1 != 'all':
   q.append(Q(param_1__name=param_1))
if param_2 != 'all':
   q.append(Q(param_2__name=param_2))

details = ClassName.objects.filter(reduce(AND, q))
👤Abhishek

1👍

Querysets are lazy. There won’t be a database query until the queryset is evaluated, usually by iterating. You’re free to apply as many filters as you like at virtually no cost.

One note: filter() does not change the queryset, but rather returns a new queryset. The correct way to apply additional filters would be:

class_var = class_var.filter(param_1__name=param_1)
👤knbk

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