Tutorial by Examples

Models are typically defined in the models.py file under your application subdirectory. The Model class of django.db.models module is a good starting class to extend your models from. For example: from django.db import models class Book(models.Model): title = models.CharField(max_length=100...

After creating a new model or modifying existing models, you will need to generate migrations for your changes and then apply the migrations to the specified database. This can be done by using the Django's built-in migrations system. Using the manage.py utility when in the project root directory: ...

Many-to-One Relationship from django.db import models class Author(models.Model): name = models.CharField(max_length=50) #Book has a foreignkey (many to one) relationship with author class Book(models.Model): author = models.ForeignKey(Author, on_delete=models.CASCADE) publish_...

Django ORM is a powerful abstraction that lets you store and retrieve data from the database without writing sql queries yourself. Let's assume the following models: class Author(models.Model): name = models.CharField(max_length=50) class Book(models.Model): name = models.CharField(max...

At some point in your use of Django, you may find yourself wanting to interact with tables which have already been created, or with database views. In these cases, you would not want Django to manage the tables through its migrations. To set this up, you need to add only one variable to your model's...

A model can provide a lot more information than just the data about an object. Let's see an example and break it down into what it is useful for: from django.db import models from django.urls import reverse from django.utils.encoding import python_2_unicode_compatible @python_2_unicode_compati...

Once a model object has been fetched, it becomes a fully realized instance of the class. As such, any additional methods can be accessed in forms and serializers (like Django Rest Framework). Using python properties is an elegant way to represent additional values that are not stored in the databa...

To create a human-readable presentation of a model object you need to implement Model.__str__() method (or Model.__unicode__() on python2). This method will be called whenever you call str() on a instance of your model (including, for instance, when the model is used in a template). Here's an exampl...

In same cases different models could have same fields and same procedures in the product life cycle. To handle these similarities without having code repetition inheritance could be used. Instead of inheriting a whole class, mixin design pattern offers us to inherit (or some says include) some met...

A model by default will use an auto incrementing (integer) primary key. This will give you a sequence of keys 1, 2, 3. Different primary key types can be set on a model with a small alterations to the model. A UUID is a universally unique identifier, this is 32 character random identifier which ca...

Inheritance among models can be done in two ways: a common abstract class (see the "Model mixins" example) a common model with multiple tables The multi tables inheritance will create one table for the common fields and one per child model example: from django.db import models c...