如何在Python中与多个类建立关系?或者如何在另一个类中创建类对象

Question

我在python中为后端工作创建了一个模型

这是我的python代码

class User:
def __init__(self, _id=None):
self._id = _id
if self._id is not None:
self.contact = Contact()
self.contact.user_id = self._id

class Contact:
def __init__(self, _id=None):
self._id = _id
self.user_id = None
if self._id is not None:
self.vehicle = Vehicle()
self.vehicle.contact_id = self._id

class Vehicle:
def __init__(self, _id=None):
self._id = _id
self.contact_id = None
self.user_id = None
def create_company(self, company_name):
# check if user id is set
if None in (self.contact_id, self.user_id):
return {'result': False, 'msg': 'user or contact id is not set'}
# here i will use user id and contact id
return {'result': True, 'msg' : 'ok'}

我想创建一个链接到用户id和联系人id 的汽车公司

我想这样做

User('user_id').Contact('contact_id').vehicle.create_company('any name')

但我遇到了一个错误，我知道为什么，但不知道如何实现解决方案

我得到错误

AttributeError: 'User' object has no attribute 'Contact'

Answer 1

不知怎么的，我通过这段代码实现了，请建议更好的方法。

class User:
def __init__(self, _id=None):
self._id = _id
def Contact(self, _id):
if self._id is None:
raise Exception({'result':False, 'msg': 'user id is not set'})
self.contact = Contact(_id)
self.contact.user_id = self._id

class Contact:
def __init__(self, _id=None):
self._id = _id

def Vehicle(self):
if self._id is None:
raise Exception({'result': False, 'msg': 'contact id is not set'})
self.vehicle = Vehicle()
self.vehicle.contact_id = self._id
if hasattr(self, 'user_id'):
self.vehicle.user_id = self.user_id

class Vehicle:
def __init__(self, _id=None):
self._id = _id
def create_company(self, company_name=None):
# check if user id is set
if not hasattr(self, 'user_id') or not hasattr(self, 'contact_id'):
return {'result': False}
# here i will use user id and contact id
return {'result': True, 'msg' : 'ok'}

并像这个一样使用它

test = User('admin')
test.Contact('person')
test.contact.Vehicle()
print(test.contact.vehicle.create_company())

结果就是我想要的

{'result': True, 'msg': 'ok'}