queryset.update is not working in for loop

Question

I want to change the name for any database variable if its match abc.

def icall(modeladmin, request, queryset):
    for pri in queryset:
        print('from test:', pri.name, pri.title) # priting if working fine
        if pri.name == 'abc':        # loop is matching the condition
            pri.update(name='zzz')  ## the value is not getting update in DB
        else:                                      
            print("gg not mached")

the pri.update(name='zzz') os not working here.

can someone please help me to know the correct statement to update the database based on the if else condition.

Please look into this https://docs.djangoproject.com/en/1.11/ref/models/conditional-expressions/#conditional-update — itzMEonTV, Dec 06 '17 at 08:52

score 2 · Answer 1 · edited Dec 06 '17 at 08:27

2

def icall(modeladmin, request, queryset):
    for pri in queryset:
        print('from test:', pri.name, pri.title)
        if pri.name == 'abc':
            pri.name ='zzz'
            pri.save()
            print("working")
        else:
            print("gg not mached")

edited Dec 06 '17 at 08:27

aprasanth

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answered Dec 06 '17 at 06:33

Nishant Thakur

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Sandeep Balagopal · Answer 2 · 2017-12-06T06:39:14.403

1

Update query is done on a queryset. It is not done on a single object like you are trying to do. You can simply do

queryset.filter(name='abc').update(name='zzz')

edited Dec 06 '17 at 06:39

answered Dec 06 '17 at 06:34

Sandeep Balagopal

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I dont think you need queryset.objects.filter, simply queryset.filter would be enough – rajkris Dec 06 '17 at 06:38

rajkris · Answer 3 · 2017-12-06T07:57:33.273

0

You cannot update a single object using the update query. Can update objects in a queryset as a whole using update. Please refer the document for clarification: Django Update query

In your case. You can do:

queryset.filter(name='abc').update(name='zzz')

instead of the for-loop.

OR

for pri in queryset:
    if pri.name == 'abc':        # loop is matching the condition
        pri.name='zzz'
        pri.save() # save the updated value

This is in case you have signals attached to your models. The Update query does not actually use django save and consequently does not emit pre_save, post_save signals.

edited Dec 06 '17 at 07:57

answered Dec 06 '17 at 06:36

rajkris

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perfect is there any way to match queryset.filter(name='abc') in if condition? – Nishant Thakur Dec 06 '17 at 08:28
if queryset.filter(name == 'abc'): then : do something if queryset.filter(name == 'def'): then : do something – Nishant Thakur Dec 06 '17 at 08:29
"do something"...is it updating fields? – rajkris Dec 06 '17 at 08:32
Yes you can do that. – rajkris Dec 06 '17 at 08:43
if re.match(regex, content) is not None: blah.. got it :) – Nishant Thakur Dec 07 '17 at 15:08
Please mark upvote the answer if it helped to find the solution t your question ;) – rajkris Dec 07 '17 at 15:32

queryset.update is not working in for loop

3 Answers3