When retrieving a single record in Django, the ORM offers two possible methods: .get() and .first(). Let's learn how each one works and when to use them.

Get

Django's most basic way to retrieve a single record is the .get() method. It is used as follows:

burger = Menu.objects.get(name="Beef Burger")

Quick facts about .get():

• It retrieves only one record.

• If no record exists that meets the given criteria, it raises a DoesNotExist exception.

• If more than one record with the given criteria exists, it raises a MultipleObjectsReturned exception.

First

A different way to get one record is …

Should you use class-based views (CBV's) or function-based views (FBV's) in Django? It seems a lot of people are pushing CBV's, touting them to be the "standard" way of writing views in Django. But why do FBV's still exist then? Just for backward-compatibility? This is my highly opinionated "view" (see what I did there??) on this matter.

The topic is hotly debated. Why are some people so passionate about CBV's? CBVs are said to be better because they abstract a lot of boiler-plate code into base classes and mixins. This is true. As a very basic example, instead of writing …

To save data in Django, you normally use .save() on a model instance. However the ORM also provides a .update() method on queryset objects. So which one should you use? Let's take a look at each, and then decide which one to use in which situations.

Save

The .save() method is used to write a model instance to the database. It can be an existing record or even a new one. For an existing record, Django will run a SQL UPDATE statement on the database. For a new record, Django will run an INSERT. Before Django 3.0, it would …

The .exists() function of Django's ORM is very useful. However, if you need to do this in bulk (think hundreds of thousands or more), this becomes a strain on your database. Let's say you are fetching records from an external system, and if the record doesn't exist locally, you need to do something:

for item in external_records:
    if not Data.objects.filter(external_id=item.id).exists():
        # Do something

If you are working with a large quantity of records, this will flood your DB with queries. Instead, you could first pull all external_id values from the DB:

existing_ids = Data.objects.all …