Django check for any exists for a query


In django how to check whether any entry exists for a query


This was how it was done in php

if(mysql_num_rows($resultn)) {
    // True condition
else {
    // False condition
2/29/2016 7:35:29 PM

Accepted Answer

Use count():


if sc.count() > 0:

The advantage over e.g. len() is, that the QuerySet is not yet evaluated:

count() performs a SELECT COUNT(*) behind the scenes, so you should always use count() rather than loading all of the record into Python objects and calling len() on the result.

Having this in mind, When QuerySets are evaluated can be worth reading.

If you use get(), e.g. scorm.objects.get(pk=someid), and the object does not exists, an ObjectDoesNotExist exception is raised:

from django.core.exceptions import ObjectDoesNotExist
    sc = scorm.objects.get(pk=someid)
except ObjectDoesNotExist:
    print ...

Update: it's also possible to use exists():

if scorm.objects.filter(

Returns True if the QuerySet contains any results, and False if not. This tries to perform the query in the simplest and fastest way possible, but it does execute nearly the same query as a normal QuerySet query.

4/2/2018 10:14:51 PM

As of Django 1.2, you can use exists():

if some_queryset.filter(pk=entity_id).exists():
    print("Entry contained in queryset")

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