实体框架更新对象和更改引用

Question

我试图更新CustomerRailcard对象，该对象在Railcard对象上有一个引用，其结尾*为1。问题是，我无法删除Railcard对象，只能更改引用将CustomerRailcard对象指向另一个RailcardObject。 我在做这样的：

UPDATE：

// Updating properties in existing CustomerRailcard. 
// This won't update navigation properties (Railcard). 
context.ObjectStateManager.ChangeObjectState(existingCustomerRailcard, EntityState.Modified); 
context.ApplyCurrentValues("CustomerRailcardsDbo", newCustomerRailcard); 

// Now I'm trying to update navigation property of CustomerRailcard to the Railcard 
// by removing the reference from old Railcard to CustomerRailcard. 
// Railcard can have references to many CustomerRailcards. 
var oldRailcard = railcardRepository.FindById(customerDetails.CustomerRailcards.FirstOrDefault(r => r.Id == railcard.Id).Railcard.Id); 
var customerRailcardToRemove = oldRailcard.CustomerRailcards.FirstOrDefault(cr => cr.Id == railcard.Id); 

// Removing reference to CustomerRailcard from Railcard 
oldRailcard.CustomerRailcards.Remove(customerRailcardToRemove); 


// Now I'm getting new Railcard I want to have referenced by CustomerRailcard 
// and I'm changing its reference tu CustomerRailcard 
var newRailcard = railcardRepository.FindById(railcard.Railcard.Id); 

// Adding reference to CustomerRailcard 
newRailcardDboReference.CustomerRailcards.Add(railcard); 

运行在这之后，我会得到这个错误

从“CR_RL_FK” AssociationSet的关系是“被删除”状态。考虑到多重性约束，相应的'CustomerRailcardDbo'也必须处于'已删除'状态。

我该如何执行这种关系的更新？

Answer 1

仅从导航属性中删除customerReilcardToRemove是不够的 - 比只打破关系，但不会删除CustomerReilcard实例。您的关系要求CustomerReilcard有一个主体Reilcard，因此您必须通过调用DeleteObject来删除customerReilcardToRemove实例，或者将关系设为空并保留孤立实例。