python - 递归问题

Question

当我从一个类导入另一个类时遇到问题。我有不同模块中的那些类:

crm.py

from CRMContactInformation import CRMContactInformation

class CRM(rdb.Model):
        """Set up crm table in the database"""
        rdb.metadata(metadata)
        rdb.tablename("crms")

        id = Column("id", Integer, ForeignKey("screens.id"),
primary_key=True)
        screen_id = Column("screen_id", Integer, )

        contactInformation = relationship(CRMContactInformation,
userlist=False, backref="crms")
        ....

CRMContactInformation.py

from CRM import CRM

class CRMContactInformation(rdb.Model):
        """Set up crm contact information table in the database"""
        rdb.metadata(metadata)
        rdb.tablename("crm_contact_informations")

        id = Column("id", Integer, ForeignKey(CRM.id), primary_key=True)
        owner = Column("owner", String(50))
        .....

如你所见，我有一个递归问题，因为我导入CRM中的CRMContactInformation和CRM中的CRMContactInformation。我有此错误或类似错误:

“AttributeError:‘module’对象没有属性”

我试图更改导入整个路径的导入。没用要么出去。

有什么方法可以使用元数据对象来访问表的属性？还是另一种方法来解决这个问题？

提前致谢!

Answer 1

延迟导入:

class CRM(rdb.Model):
        """Set up crm table in the database"""
        rdb.metadata(metadata)
        rdb.tablename("crms")

        id = Column("id", Integer, ForeignKey("screens.id"), primary_key=True)
        screen_id = Column("screen_id", Integer, )

        ....

from CRMContactInformation import CRMContactInformation
CRM.contactInformation = relationship(CRMContactInformation, userlist=False, backref="crms")