Django 测试：Postgres 上的 setUpTestData 抛出：“重复的键值违反了唯一约束”

我在单元测试中遇到数据库问题。我认为这与我使用 TestCase 和 setUpData 的方式有关。

当我尝试使用某些值设置测试数据时，测试会抛出以下错误：

django.db.utils.IntegrityError: duplicate key value violates unique constraint 

...

psycopg2.IntegrityError: duplicate key value violates unique constraint "InventoryLogs_productgroup_product_name_48ec6f8d_uniq"
DETAIL:  Key (product_name)=(Almonds) already exists.

我更改了所有主键，它似乎运行良好。它似乎不会影响任何测试。

但是，我担心我做错了什么。当它第一次发生时，我在我的应用程序上逆转了大约一个小时的工作（对于菜鸟来说没有那么多代码），这纠正了问题。

然后，当我写回更改时，同样的问题再次出现。下面粘贴了测试用例。该问题似乎是在我添加 sortrecord 项目后发生的，但与其上面的项目相对应。

我不想在测试中继续检查和更改主键和 url，因此如果有人发现我使用此方法的方式有问题，请帮助我。谢谢！

TestCase

class DetailsPageTest(TestCase):


@classmethod
def setUpTestData(cls):

    cls.product1 = ProductGroup.objects.create(
                        product_name="Almonds"
                        )
    cls.variety1 = Variety.objects.create(
                        product_group = cls.product1,
                        variety_name = "non pareil",
                        husked = False,
                        finished = False,
                        )

    cls.supplier1 = Supplier.objects.create(
                        company_name = "Acme",
                        company_location = "Acme Acres",
                        contact_info = "Call me!"
                        )

    cls.shipment1 = Purchase.objects.create(
                        tag=9,
                        shipment_id=9999,
                        supplier_id = cls.supplier1,
                        purchase_date='2015-01-09',
                        purchase_price=9.99,
                        product_name=cls.variety1,
                        pieces=99,
                        kgs=999,
                        crackout_estimate=99.9
                        )
    cls.shipment2 = Purchase.objects.create(
                        tag=8,
                        shipment_id=8888,
                        supplier_id=cls.supplier1,
                        purchase_date='2015-01-08',
                        purchase_price=8.88,
                        product_name=cls.variety1,
                        pieces=88,
                        kgs=888,
                        crackout_estimate=88.8
                        )
    cls.shipment3 = Purchase.objects.create(
                        tag=7,
                        shipment_id=7777,
                        supplier_id=cls.supplier1,
                        purchase_date='2014-01-07',
                        purchase_price=7.77,
                        product_name=cls.variety1,
                        pieces=77,
                        kgs=777,
                        crackout_estimate=77.7
                        )

    cls.sortrecord1 = SortingRecords.objects.create(
                        tag=cls.shipment1,
                        date="2015-02-05",
                        bags_sorted=20,
                        turnout=199,
                        )

    cls.sortrecord2 = SortingRecords.objects.create(
                        tag=cls.shipment1,
                        date="2015-02-07",
                        bags_sorted=40,
                        turnout=399,
                        )
    cls.sortrecord3 = SortingRecords.objects.create(
                        tag=cls.shipment1,
                        date='2015-02-09',
                        bags_sorted=30,
                        turnout=299,
                        )

Models

from datetime import datetime

from django.db import models
from django.db.models import Q


class ProductGroup(models.Model):
    product_name = models.CharField(max_length=140, primary_key=True)

    def __str__(self):
        return self.product_name

    class Meta:
        verbose_name = "Product"

class Supplier(models.Model):
    company_name = models.CharField(max_length=45)
    company_location = models.CharField(max_length=45)
    contact_info = models.CharField(max_length=256)

    class Meta:
        ordering = ["company_name"]

    def __str__(self):
        return self.company_name

class Variety(models.Model):
    product_group = models.ForeignKey(ProductGroup)
    variety_name = models.CharField(max_length=140)
    husked = models.BooleanField()
    finished = models.BooleanField()
    description = models.CharField(max_length=500, blank=True)

    class Meta:
        ordering = ["product_group_id"]
        verbose_name_plural = "Varieties"

    def __str__(self):
        return self.variety_name


class PurchaseYears(models.Manager):

    def purchase_years_list(self):
        unique_years = Purchase.objects.dates('purchase_date', 'year')
        results_list = []
        for p in unique_years:
            results_list.append(p.year)
        return results_list


class Purchase(models.Model):
    tag = models.IntegerField(primary_key=True)
    product_name = models.ForeignKey(Variety, related_name='purchases')
    shipment_id = models.CharField(max_length=24)
    supplier_id = models.ForeignKey(Supplier)
    purchase_date = models.DateField()
    estimated_delivery = models.DateField(null=True, blank=True)
    purchase_price = models.DecimalField(max_digits=6, decimal_places=3)
    pieces = models.IntegerField()
    kgs = models.IntegerField()
    crackout_estimate = models.DecimalField(max_digits=6,decimal_places=3, null=True)
    crackout_actual = models.DecimalField(max_digits=6,decimal_places=3, null=True)
    objects = models.Manager()
    purchase_years = PurchaseYears()
    # Keep manager as "objects" in case admin, etc. needs it. Filter can be called like so:
    # Purchase.objects.purchase_years_list()
    # Managers in docs: https://docs.djangoproject.com/en/1.8/intro/tutorial01/

    class Meta:
        ordering = ["purchase_date"]

    def __str__(self):
        return self.shipment_id

    def _weight_conversion(self):
        return round(self.kgs * 2.20462)
    lbs = property(_weight_conversion)

class SortingModelsBagsCalulator(models.Manager):

    def total_sorted(self, record_date, current_set):
        sorted = [SortingRecords['bags_sorted'] for SortingRecords in current_set if
                  SortingRecords['date'] <= record_date]
        return sum(sorted)


class SortingRecords(models.Model):
    tag = models.ForeignKey(Purchase, related_name='sorting_record')
    date = models.DateField()
    bags_sorted = models.IntegerField()
    turnout = models.IntegerField()
    objects = models.Manager()

    def __str__(self):
        return "%s  [%s]" % (self.date, self.tag.tag)

    class Meta:
        ordering = ["date"]
        verbose_name_plural = "Sorting Records"

    def _calculate_kgs_sorted(self):
        kg_per_bag = self.tag.kgs / self.tag.pieces
        kgs_sorted = kg_per_bag * self.bags_sorted
        return (round(kgs_sorted, 2))
    kgs_sorted = property(_calculate_kgs_sorted)

    def _byproduct(self):
        waste = self.kgs_sorted - self.turnout
        return  (round(waste, 2))
    byproduct = property(_byproduct)

    def _bags_remaining(self):
        current_set = SortingRecords.objects.values().filter(~Q(id=self.id), tag=self.tag)
        sorted = [SortingRecords['bags_sorted'] for SortingRecords in current_set if
                  SortingRecords['date'] <= self.date]
        remaining = self.tag.pieces - sum(sorted) - self.bags_sorted
        return remaining
    bags_remaining = property(_bags_remaining)

EDIT

它对于整数也会失败，就像这样。

django.db.utils.IntegrityError: duplicate key value violates unique constraint "InventoryLogs_purchase_pkey"
DETAIL:  Key (tag)=(9) already exists.

UDPATE

所以我应该早点提到这一点，但我完全忘记了。我有两个使用相同数据的单元测试文件。只是为了好玩，我在两个实例中都匹配了主键setUpTestData()到不同的值，果然，我得到了同样的错误。

在我向其中之一添加更多数据之前，这两个设置并排工作得很好。现在看来，他们需要不同的价值观。我想你只能在这么长时间内使用重复数据。

几个月来我偶尔遇到这个问题。我相信我刚刚找到了根本原因和几个解决方案。

Summary无论出于何种原因，Django 测试用例基类似乎没有删除由我们调用它创建的数据库记录TestCase1跑步前TestCase2。其中，在TestCase2当它尝试使用与以下相同的 ID 在数据库中创建记录时TestCase1数据库提出了一个DuplicateKey异常，因为这些 ID 已存在于数据库中。即使说“请”这个神奇的词也无助于解决数据库重复键错误。

好消息是，有多种方法可以解决这个问题！这里有几个...

解决方案1

确保您是否重写了类方法tearDownClass你所说的super().tearDownClass()。如果你覆盖tearDownClass()如果不调用它的 super，它又永远不会调用TransactionTestCase._post_teardown() nor TransactionTestCase._fixture_teardown()。引用 TransactionTestCase._post_teardown()` 中的文档字符串：

    def _post_teardown(self):
        """
        Perform post-test things:
        * Flush the contents of the database to leave a clean slate. If the
          class has an 'available_apps' attribute, don't fire post_migrate.
        * Force-close the connection so the next test gets a clean cursor.
        """

If TestCase.tearDownClass()不是通过调用super()那么数据库不会在测试用例之间重置，您将得到可怕的重复键异常。

解决方案2

覆盖TransactionTestCase并设置类变量serialized_rollback = True， 像这样：

class MyTestCase(TransactionTestCase):
    fixtures = ['test-data.json']
    serialized_rollback = True

    def test_name_goes_here(self):
        pass

引用来源：

class TransactionTestCase(SimpleTestCase):

    ...

    # If transactions aren't available, Django will serialize the database
    # contents into a fixture during setup and flush and reload them
    # during teardown (as flush does not restore data from migrations).
    # This can be slow; this flag allows enabling on a per-case basis.
    serialized_rollback = False

When serialized_rollback被设定为True，Django 测试运行程序会回滚测试用例之间插入数据库的任何事务。 Batta bing、batta bang...不再有重复的按键错误！

结论

可能还有很多方法可以实现OP问题的解决方案，但这两种方法应该可以很好地工作。为了清楚起见并更深入地了解底层 Django 测试用例基类，肯定希望其他人添加更多解决方案。唷，最后一句话快说三遍，你就可以赢得一匹小马！