Creating a Base Model in Django

Created on: 2019.09.09

When building a database for your application you sometimes need specific fields across all (or a great deal of) your models. It is a good practice to include creation time and update time fields, so you can see what changed… and when. Today we will go through the code needed to implement a base model for your database containing such data.

In our main application (named like your project, I named it notes_api) let’s create a new file: models.py (just like you would do in other django apps) and add the following code. The abstract = True line tells Django, that this shouldn’t be created as a model in the database. Moreover we can add some ordering so this is easier to use.

from django.db import models


class BaseModel(models.Model):
    created_at = models.DateTimeField(
        auto_now_add=True,
        db_index=True
    )
    updated_at = models.DateTimeField(
        auto_now=True,
        db_index=True
    )

    class Meta:
        abstract = True
        ordering = ['created_at']

Let’s consider now having a Note model somewhere in our Django system. Instead of adding the created_at and updated_at fields to each model, we can now use our freshly created BaseModel to do that for us:

from django.db import models
from notes_api.models import BaseModel


class Note(BaseModel):
    description = models.CharField(
        max_length=255,
    )

Now, if we look at the model in the database, it will consists of 3 fields: The note description, the time at which it was created and the last update time.