更改:

class Project(models.Manager)

收件人:

class Project(models.Model)

因为models.Model是实际类，必须扩展才能创建自定义模型，并且实际上还使用管理器来覆盖所涉及的数据库操作模型.

because models.Model is actual class you must extend to create custom models, and managers are actually used to override database operations models are involved in.