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This chapter is from the book

This chapter is from the book

Designing Your Model

We’ve now arrived at the core of your Django-based blog application: the models.py file. This is where we’ll define the data structures of the blog. Following the principle of Don’t Repeat Yourself (DRY), Django gets a lot of mileage out of the model information you provide for your application. Let’s create a basic model, and then see all the stuff Django does for us using that information.

Open up models.py in your favorite text editor (bonus points if it has a Python mode with syntax coloring). You see this placekeeper text:

from django.db import models

# Create your models here.

Delete the comment, and then add the following lines:

class BlogPost(models.Model):
    title = models.CharField(max_length=150)
    body = models.TextField()
    timestamp = models.DateTimeField()

That’s a complete model, representing a “BlogPost” object with three fields. (Actually, strictly speaking it has four fields—Django automatically creates an auto-incrementing, unique id field for each model by default.)

You can see our newly minted class, BlogPost, is a subclass of django.db.models.Model. That’s Django’s standard base class for data models, which is the core of Django’s powerful object-relational mapping system. Also, you notice our fields are defined like regular class attributes with each one being an instance of a particular field class. Those field classes are also defined in django.db.models, and there are many more types—ranging from BooleanField to XMLField—than the three we’re using here.

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