Re: QuerySet: "if obj in queryset" can be very slow

That's because your queryset is being evaluated when you compare, maybe if you explain your problem, we can give you a better solution than the use of `in`.

Take a look at the docs about when querysets are evaluated:

https://docs.djangoproject.com/en/dev/ref/models/querysets/#when-querysets-are-evaluated

[]'s

On Wed, Nov 2, 2011 at 9:42 AM, Thomas Guettler <hv@tbz-pariv.de> wrote:

Hi,

I just discovered, that "if obj in queryset" can be very slow:

queryset=MyModel.objects.all()
obj=MyModel.objects.get(id=319526)

#if obj in queryset: # This is very slow, if queryset is big: All lines from queryset get created to Python objects
#    print 'in'

if queryset.filter(id=obj.id): # Fast: Check is done inside DB.
   print 'in'

What is the best way to do "if obj in queryset"?

 Thomas

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Thomas Guettler, http://www.thomas-guettler.de/
E-Mail: guettli (*) thomas-guettler + de

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