Question

I would like to merge one querysets related objects with another querysets related objects. Some sample code to explain:

## Models # sample models to illustrate problem class PetShop(models.Model):     id = models.AutoField(primary_key=True)     shop_name = models.CharField(maxlength=255)     cats = models.ManyToManyField(Cat)  class Cat(models.Model):     id = models.AutoField(primary_key=True)     cat_name = models.CharField(maxlength=50, blank=True)   ## View def MergePetsInShop(request):     source_shop = PetShop.objects.get(pk=2)     destination_shop = PetShop.objects.get(pk=3)      #Somehow merge CATS from one shop to the other     result = merge(source_shop.cats,destination_shop.cats)      #save() 

How can I do this properly?

Many thanks.

Answer 1

You can take advantage of the fact that Django’s many-to-many manager functions add and remove accept any number of positional arguments. In this case, I’d try:

destination_shop.cats.add(*source_shop.cats.all())