django model field get set method with full example

Sure, here is a full example of how to use the get and set methods for a Django model field:

Let's say we have a model called Person that has a name field. We want to transform the name to uppercase when it's retrieved from the database, and we want to transform it to lowercase when it's saved to the database. We can achieve this using the get and set methods of the CharField model field.

First, we define our Person model:

from django.db import models

class Person(models.Model):
    name = models.CharField(max_length=100)

Next, we define a custom CharField that overrides the get and set methods:

class UppercaseCharField(models.CharField):
    def get(self, instance, owner):
        value = super().get(instance, owner)
        return value.upper()

    def set(self, instance, value):
        value = value.lower()
        super().set(instance, value)

In the get method, we retrieve the value of the field using the super() method, then transform it to uppercase using the upper() method, and return the transformed value.

In the set method, we transform the value to lowercase using the lower() method, then call the super() method to set the value on the instance.

Finally, we update our Person model to use our custom UppercaseCharField:

class Person(models.Model):
    name = UppercaseCharField(max_length=100)

Now, whenever we retrieve a Person instance from the database, the name field will be automatically transformed to uppercase. When we save a Person instance to the database, the name field will be automatically transformed to lowercase.

Here's an example of how to use our Person model:

>>> p = Person(name='John')
>>> p.save()
>>> p.name
'JOHN'
>>> p.name = 'Mary'
>>> p.save()
>>> p.name
'mary'

As you can see, the name field is automatically transformed to uppercase when it's retrieved from the database, and to lowercase when it's saved to the database.