使用factory-boy创建Django模型时触发主键重复IntegrityError

运行测试时出现以下错误：

django.db.utils.IntegrityError: duplicate key value violates unique constraint "shops_shop_pkey"
DETAIL:  Key (id)=(cd84e095-7d1a-41fc-adb3-7f5db5e07d50) already exists.
========================================================================== short test summary info ===========================================================================
FAILED tests/models/test_shop.py::test_shop_creation - django.db.utils.IntegrityError: duplicate key value violates unique constraint "shops_shop_pkey"

我用factory-boy创建了ShopModelFactory工厂类，用来生成Django的Shop模型，字段用faker填充，之后用pytest编写测试。数据库是空的，测试前也删除了所有记录，后台管理面板能正常创建记录，但测试始终报主键重复错误。

我的Shop模型 #

class Shop(TimedBaseModel):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    first_name = models.CharField("First Name", max_length=20)
    last_name = models.CharField("Last Name", max_length=20)
    email = models.EmailField("Email", unique=True)
    phone = PhoneNumberField(
        "Phone Number",
        unique=True,
    )
    shop_name = models.CharField("Shop Name", max_length=50, unique=True)
    shop_url = models.URLField("Shop URL", unique=True)
    logo = models.ImageField("Logo", upload_to="logos/", blank=True, null=True)
    banner = models.ImageField(
        "Banner",
        upload_to="banners/",
        blank=True,
        null=True,
    )
    street1 = models.CharField("Street 1", max_length=50)
    street2 = models.CharField("Street 2", max_length=50, blank=True)
    city = models.CharField("Town / City", max_length=100)
    zip_code = models.CharField("Zip Code", max_length=10)
    country = CountryField("Country", blank_label="(select country)")
    state = models.CharField("State", max_length=100, blank=True, default="")
    password = models.CharField("Password")
    confirm_password = models.CharField("Confirm Password")
    is_visible = models.BooleanField(
        verbose_name="Is the shop visible in the shops catalog",
        default=True,
    )

    class Meta:
        verbose_name = "Խանութ"
        verbose_name_plural = "Խանութներ"
        app_label = "shops"

    def __str__(self):
        return self.shop_name

    def save(self, *args, **kwargs):
        instance = super().save(*args, **kwargs)
        if self.logo:
            instance = super().save(*args, **kwargs)
            logo_path = self.logo.path

            logo = Image.open(logo_path)
            logo_size = os.path.getsize(logo_path)  # in bytes
            thirty_mb = 30 * 1024 * 1024

            while logo_size > thirty_mb:
                logo = logo.convert("RGB")
                logo.save(
                    logo_path,
                    quality=60,
                    optimize=True,
                    format="JPEG",
                )
        return instance

我的工厂类 #

import factory
from factory.django import DjangoModelFactory, ImageField
from api.v1.apps.shops.models.shops import Shop


class ShopModelFactory(DjangoModelFactory):
    class Meta:
        model = Shop

    
    first_name = factory.Faker('first_name')
    last_name = factory.Faker('last_name')
    email = factory.Faker('email')
    phone = factory.Faker('phone_number')
    shop_name = factory.Faker('company')
    shop_url = factory.Faker('url')
    logo = ImageField(color='blue')
    banner = ImageField(color='red')
    street1 = factory.Faker('street_address')
    street2 = factory.Faker('secondary_address')
    city = factory.Faker('city')
    zip_code = factory.Faker('postcode')
    country = factory.Faker('country_code')
    state = factory.Faker('state')
    password = factory.Faker('password')
    confirm_password = password
    is_visible = factory.Faker('boolean')

我的测试代码 #

@pytest.mark.django_db(transaction=True)
def test_shop_creation():
    Shop.objects.all().delete()  # 生成实例前已删除所有数据库记录
    shop = ShopModelFactory()
    assert Shop.objects.count() == 1
    assert Shop.objects.first() == shop
    assert shop.first_name
    assert shop.last_name
    assert shop.email
    assert shop.phone
    assert shop.shop_name
    assert shop.shop_url
    assert shop.street1
    assert shop.city
    assert shop.zip_code
    assert shop.country
    assert shop.state
    assert shop.password
    assert shop.confirm_password
    assert isinstance(shop.is_visible, bool)

问题原因及解决办法 #

1. save方法重复调用导致主键冲突
   你的Shop模型save方法中，处理logo时额外调用了一次super().save()，这会导致同一个实例被保存两次：第一次保存时已生成UUID主键，第二次保存时尝试用相同主键再次插入，触发唯一约束错误。
   修改后的save方法：

   def save(self, *args, **kwargs):
       instance = super().save(*args, **kwargs)
       if self.logo:
           logo_path = self.logo.path
   
           logo = Image.open(logo_path)
           logo_size = os.path.getsize(logo_path)  # in bytes
           thirty_mb = 30 * 1024 * 1024
   
           while logo_size > thirty_mb:
               logo = logo.convert("RGB")
               logo.save(
                   logo_path,
                   quality=60,
                   optimize=True,
                   format="JPEG",
               )
               # 重新获取压缩后的文件大小，避免无限循环
               logo_size = os.path.getsize(logo_path)
       return instance
   

2. 显式指定工厂类的UUID生成逻辑
   虽然模型设置了default=uuid.uuid4，但factory-boy可能不会正确触发默认值生成。在工厂类中显式添加id字段，确保每次生成新实例时生成唯一UUID：

   import uuid
   # 在ShopModelFactory中添加
   id = factory.LazyFunction(uuid.uuid4)
   

3. 调整测试事务模式
   使用@pytest.mark.django_db(transaction=True)会让测试在事务中运行，删除操作的效果可能受事务隔离影响。可以改用transaction=False，或使用pytest-django的默认django_db标记（默认不使用事务）。

内容的提问来源于stack exchange，提问作者user22795766