python - 类型错误 : 'UniqueConstraint' object is not iterable in Django

Question

当我使用 UniqueConstraint 设置多个唯一字段时:

class Meta:
    constraints = (models.UniqueConstraint(fields=['student', 'classroom', 'code'], name='student_classroom_code'))

并运行 python manage.py makemigrations 引发此错误:

TypeError: 'UniqueConstraint' object is not iterable

这是怎么回事？

Answer 1

您需要将可迭代分配给约束。您在 (models.UniqueConstraint(...),) 中缺少 ,，这意味着您分配的是 models.UniqueConstraint 实例而不是元组.

class Meta:
    constraints = (models.UniqueConstraint(fields=['student', 'classroom', 'code'], name='student_classroom_code'),)