ValueError: The QuerySet value for an exact lookup must be limited to one result using slicing.

student = Student.objects.filter(student=user)

ValueError: The QuerySet value for an exact lookup must be limited to one result using slicing.

原因：student 查询的结果是一个结果集（QuerySet），在Student.objects.filter(student=user)的筛选条件必须是一个对象而不是一个结果集。

student = Student.objects.filter(student=user).first()