django/tests/defer/models.py

"""
Tests for defer() and only().
"""

from django.db import models


class Secondary(models.Model):
    first = models.CharField(max_length=50)
    second = models.CharField(max_length=50)


class Primary(models.Model):
    name = models.CharField(max_length=50)
    value = models.CharField(max_length=50)
    related = models.ForeignKey(Secondary, models.CASCADE)

    def __str__(self):
        return self.name


class Child(Primary):
    pass


class BigChild(Primary):
    other = models.CharField(max_length=50)


class ChildProxy(Child):
    class Meta:
        proxy = True


class RefreshPrimaryProxy(Primary):
    class Meta:
        proxy = True

    def refresh_from_db(self, using=None, fields=None, **kwargs):
        # Reloads all deferred fields if any of the fields is deferred.
        if fields is not None:
            fields = set(fields)
            deferred_fields = self.get_deferred_fields()
            if fields.intersection(deferred_fields):
                fields = fields.union(deferred_fields)
        super().refresh_from_db(using, fields, **kwargs)