Django manger is an interface through which the django model queries the database. The
objects field used in most django queries is actually the default manager created for us by django (this is only created if we don't define custom managers).
Why would we define a custom manager/queryset?
To avoid writing common queries all over our codebase and instead referring them using an easier to remember abstraction. Example: Decide for yourself which version is more readable :
Another benefit is that if tomorrow we decide all
psychologists are also
dermatologists, we can easily modify the query in our Manager and be done with it.
Below is an example of creating a custom
Manager defined by creating a
QuerySet and using the
from django.db.models.query import QuerySet class ProfileQuerySet(QuerySet): def doctors(self): return self.filter(user_type="Doctor", user__is_active=True) def with_specializations(self, specialization): return self.filter(specializations=specialization) def users(self): return self.filter(user_type="Customer", user__is_active=True) ProfileManager = ProfileQuerySet.as_manager
We will add it to our model as below:
class Profile(models.Model): ... manager = ProfileManager()
NOTE : Once we've defined a
manager on our model,
objects won't be defined for the model anymore.