How to create a Django GeneratedField for extracting a timestamp from a UUIDv7

I recently read How to use UUIDv7 in Python, Django and PostgreSQL from Paolo Melchiorre. I particularly liked the section demonstrating how to extend the model with a generated column that stores the timestamp extracted from the UUID.

from django.db import models


class UUIDv7(models.Func):
    function = "uuidv7"
    output_field = models.UUIDField()


class UUIDExtractTimestamp(models.Func):
    function = "uuid_extract_timestamp"
    output_field = models.DateTimeField()


class Record(models.Model):
    uuid = models.UUIDField(db_default=UUIDv7(), primary_key=True)
    creation_time = models.GeneratedField(
        expression=UUIDExtractTimestamp("uuid"),
        output_field=models.DateTimeField(),
        db_persist=True,
    )

As Paolo says:

A generated datetime column can be very useful even though UUIDv7 already embeds a timestamp. PostgreSQL computes it at write time, Django manages it declaratively through the ORM and having a proper datetime field makes filtering, ordering, indexing and using the Django admin much simpler without requiring annotations or extra computation on the UUID value.

Read that specific section here.