Adding Database Models

If your app introduces a new type of object in Nautobot, you'll probably want to create a Django model for it. A model is essentially a Python representation of a database table, with attributes that represent individual columns. Model instances can be created, manipulated, and deleted using queries. Models must be defined within a file named models.py.

It is highly recommended to have app models inherit from at least nautobot.apps.models.BaseModel which provides base functionality and convenience methods common to all models.

For more advanced usage, you may want to instead inherit from one of Nautobot's "generic" models derived from BaseModel -- nautobot.apps.models.OrganizationalModel or nautobot.apps.models.PrimaryModel. The inherent capabilities provided by inheriting from these various parent models differ as follows:

Feature	django.db.models.Model	BaseModel	OrganizationalModel	PrimaryModel
UUID primary key	❌	✅	✅	✅
Natural keys	❌	✅	✅	✅
Object permissions	❌	✅	✅	✅
validated_save()	❌	✅	✅	✅
Change logging	❌	❌	✅	✅
Custom fields	❌	❌	✅	✅
Relationships	❌	❌	✅	✅
Note	❌	❌	✅	✅
Tags	❌	❌	❌	✅

Below is an example models.py file containing a basic model with two character fields:

# models.py
from django.db import models

from nautobot.apps.models import BaseModel


class Animal(BaseModel):
    """Base model for animals."""

    name = models.CharField(max_length=50)
    sound = models.CharField(max_length=50)

    def __str__(self):
        return self.name

    class Meta:
        unique_together = [["name", "sound"]]

Once you have defined the model(s) for your app, you'll need to create the database schema migrations. A migration file is essentially a set of instructions for manipulating the database to support your new model, or to alter existing models.

Creating migrations can be done automatically using the nautobot-server makemigrations <app_name> management command, where <app_name> is the name of the Python package for your app (e.g. nautobot_animal_sounds):

nautobot-server makemigrations nautobot_animal_sounds

Note

An app must be installed before it can be used with Django management commands. If you skipped this step above, run poetry install from the app's root directory.

nautobot-server makemigrations nautobot_animal_sounds

Example output:

Migrations for 'nautobot_animal_sounds':
  /home/bjones/animal_sounds/nautobot_animal_sounds/migrations/0001_initial.py
    - Create model Animal

Next, apply the migration to the database with the nautobot-server migrate <app_name> command:

nautobot-server migrate nautobot_animal_sounds

Example output:

Operations to perform:
  Apply all migrations: nautobot_animal_sounds
Running migrations:
  Applying nautobot_animal_sounds.0001_initial... OK

For more background on schema migrations, see the Django documentation.