如何在 Django 中自定义 related_name 参数

Question

我有一个抽象模型和两个子模型，例如：

class Invoice(models.Model):
    user = models.ForeignKey("User", related_name='%(class)s')

    class Meta:
        abstract=True

class SaleInvoice(Invoice):
    field_sale = models.CharField(max_length=255)

class PurchaseInvoice(Invoice):
    field_purchase = models.CharField(max_length=255)

现在，子模型的反向名称将是saleinvoicesand purchaseinvoices。但我需要的是sale_invoices和purchase_invoices。如何实现这一目标？CamelCase 之间有一个下划线。

Answer 1

1. 覆盖contribute_to_class()ofForeignKey以设置related_name。

class CustomFk(models.ForeignKey):
    def contribute_to_class(self, cls, name, private_only=False, **kwargs):
        super().contribute_to_class(cls, name, private_only=False, **kwargs)
        self.remote_field.related_name = "_".join(re.findall('[A-Z][^A-Z]*', cls.__name__))

2. 在抽象模型中使用此自定义 FK 字段。

class Invoice(models.Model):
    user = CustomFk(User, related_name='%(class)s')

    class Meta:
        abstract = True

# migrations file
operations = [
    migrations.CreateModel(
        name='PurchaseInvoice',
        fields=[
            ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
            ('field_purchase', models.CharField(max_length=255)),
            ('user', sample.models.CustomFk(on_delete=django.db.models.deletion.CASCADE,
                                            related_name='Purchase_Invoice', to=settings.AUTH_USER_MODEL)),
        ],
        options={
            'abstract': False,
        },
    ),
    migrations.CreateModel(
        name='SaleInvoice',
        fields=[
            ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
            ('field_sale', models.CharField(max_length=255)),
            ('user', sample.models.CustomFk(on_delete=django.db.models.deletion.CASCADE,
                                            related_name='Sale_Invoice', to=settings.AUTH_USER_MODEL)),
        ],
        options={
            'abstract': False,
        },
    ),
]

参考
*。 *。用大写字母分割字符串 - Pythoncontribute_to_class()