How does Django determine whether to perform sorting or data updating when saving a model using the save method?

Django determines whether to create a new record or update an existing one when calling the model's save() method, based on the presence of a primary key value (usually id).

• If the object has no primary key value (id is None), Django considers it a new record and performs an insert operation.
• If the object has a primary key value, Django performs an update of the existing record with that key.

Regarding sorting, Django does not automatically sort data when saving a model. Data sorting typically occurs when querying the database using methods like order_by(). The save() method is only responsible for saving the current state of the object to the database.

Example:

obj = MyModel()
obj.save()  # INSERT if obj.id does not exist yet

obj.field = 'new value'
obj.save()  # UPDATE if obj.id already exists

Thus, Django relies on the presence of a primary key to determine whether to create a new record or update an existing one.