获取 django.db.utils.IntegrityError: 重复键值违反唯一约束但值不存在

Question

我正在将 PostgreSQL 与 Django 一起使用，并且我试图使用 Django ORM 从 DB 中获取一些对象。

Medicine.objects.get(unique_item_id=26775)

但是在获取时我遇到了错误 -> item_medicine.models.DoesNotExist: Medicine matching query does not exist.

然后我尝试使用 Django ORM 插入相同的内容。

Medicine.objects.create(unique_item_id=26775)

但我再次收到错误psycopg2.errors.UniqueViolation: duplicate key value violates unique constraint "item_medicine_medicine_unique_item_id_key" DETAIL: Key (unique_item_id)=(26775) already exists.

在我的模型中，我为unique_item_id 字段添加了unique=True。

我不知道为什么会这样。我尝试了在类似帖子上给出的答案，但没有任何效果。

追溯：

Traceback (most recent call last):
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
psycopg2.errors.UniqueViolation: duplicate key value violates unique constraint "item_medicine_medicine_unique_item_id_key"
DETAIL:  Key (unique_item_id)=(26775) already exists.
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 2963, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-4-46fdec6a582b>", line 1, in <module>
    Medicine.objects.create(unique_item_id=26775)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/models/query.py", line 394, in create
    obj.save(force_insert=True, using=self.db)
  File "/home/rohit/Projects/medicine/item_medicine/models.py", line 58, in save
    super(Medicine, self).save(*args, **kwargs)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/models/base.py", line 808, in save
    force_update=force_update, update_fields=update_fields)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/models/base.py", line 838, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/models/base.py", line 924, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/models/base.py", line 963, in _do_insert
    using=using, raw=raw)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/models/query.py", line 1076, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1112, in execute_sql
    cursor.execute(sql, params)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/backends/utils.py", line 79, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/home/rohit/virtualenvs/envmedicine/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
django.db.utils.IntegrityError: duplicate key value violates unique constraint "item_medicine_medicine_unique_item_id_key"
DETAIL:  Key (unique_item_id)=(26775) already exists.

提前谢谢你们！！

Answer 1

如果您在 Medicine.objects 经理中进行任何类型的过滤，那么您很可能会遇到此问题。例如，假设您定义了以下模型和管理器。

class SoftDeleteManager(models.Manager):
    def get_queryset(self):
        return super().get_queryset().filter(deleted_at=None)

class Medecine(models.Model):
    ...
    unique_item_id = models.IntegerField(unique=True)
    deleted_at = models.DateTimeField(null=True)

    objects = SoftDeleteManager()

conflicting = Medecine.objects.create(unique_item_id=26775, deleted_at=some_datetime)

Medecine.objects.get(unique_item_id=26775)  # Results in DoesNotExist
Medecine.objects.create(unique_item_id=26775) # Results in IntegrityError

如果不是这样，那么您的 PostgreSQL 索引可能已损坏。

我建议你尝试在你的桌子上运行the REINDEX command

REINDEX TABLE item_medicine_medicine