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I have a model MyModel with a boolean field active
Elsewhere, I am retrieving a queryset:
qs = MyModel.Objects.filter(....) how can I set active=False for all objects in this qs?
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If you then use object[0] you make a query to the database to fetch the first element and deserialize it into a News_Channel object. Then you set the total_star of that object, but you never save that object. You only call . update() on the entire queryset, resulting in another independent query.
Use update_fields in save() If you would like to explicitly mention only those columns that you want to be updated, you can do so using the update_fields parameter while calling the save() method. You can also choose to update multiple columns by passing more field names in the update_fields list.
This is because a Django QuerySet is a lazy object. It contains all of the information it needs to populate itself from the database, but will not actually do so until the information is needed.
You can update all the records in the queryset with
qs.update(active=False) Please refer to the official Django documentation for more info
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And of course you can pass many arguments to update e.g.:
qs.update(active=False, is_deleted=True, date_finished=timezone.now()) Edit: Additionally. This simple qs.update(...) won't work on sliced querysets. For example if you have:
users = User.objects.filter(is_active=True)[:10] user.update(is_active=False) # This will throw error in that kind of situation, since Django 2.2, you can use bulk_update() method like:
users_to_update = list(User.objects.filter(is_active=True)[:10]) for i in range(10): users_to_update.is_active = False User.objects.bulk_update(users_to_update, ["is_active"]) This will be generally done in one query not in 10 separate queries. I've faced that kind of requirements in one of my project. Hope it will be helpful.
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