Filter queryset for many-to-many field for any foreign item matching specific criteria-CodePudding

I have 2 models:

class BackupItems(models.Model):
    name = models.CharField(max_length=100)

class CloudObjects(models.Model):
    creation_time = models.DateTimeField()
    removed_date = models.DateTimeField()
    item = models.ManyToManyField(BackupItems)

This is holding data for some backup operations. CloudObject is a table with information when item was created and when it was deleted. For legacy issues, removed date is hardcoded as 2099-12-31 for all new entries. Once it's deleted, this date is substitute with real date.

In the views I have simply query, where I list all items from BackupItems.

BackupItems.objects.all()

Now, I'd like to list only those BackupItems which have any CloudObjects in the future ( removed_date = 2099-21-31). I dont care what is that given item, if this CloudObject for given BackupItem exists in the future, it's fine for me. I don't want to see any item in queryset, where there are no CloudObjects in future for given BackupItem.

How to crate this kind of view?

CodePudding user response：

You could do this by the use of Django ORM's filter() method and passing it to the view as a context variable like so:

from django.shortcuts import render
from .models import BackupItems, CloudObjects
import datetime


def backup_items(request):
    future_date = datetime.datetime(2099, 12, 31)
    backup_items = BackupItems.objects.filter(cloudobject__removed_date=future_date).distinct()
    context = {'backup_items': backup_items}
    return render(request, 'backup_items.html', context)

This will return a queryset of BackupItems objects that have a CloudObject with a removed_date of 2099-12-31. The distinct() method ensures that each BackupItem is returned only once.