Question

查看问题"How to delete many-to-many relationship in Entity Framework without loading all of the data"的前2个答案（参见文章）表明存在导航属性集合的附加方法（即， entity1 .Entity2Collection.Attach（ entity2 ））。问题是，我有 VS 2015 / EF 6.1.3 （VB和DBContext），并且该方法似乎不存在导航属性集合（或者至少Intellisense没有＆＃39; t显示它）。我做错了吗？

Answer 1

Dannie f。的解决方案（针对VB重新编码）如下，假设有一个TopicDBEntities模型，以及主题和订阅的实体集合：

Dim db = New TopicDBEntities()

'   Create UNATTACHED instances of the two entities and associate them
'   (In real life, you would have something more sophisticated for the
'   next 2 lines)
Dim topic = New Topic { .TopicId = 1 }
Dim subscription = New Subscription { .SubscriptionId = 2}

topic.Subscriptions.Add(subscription)

'   Attach the topic and subscription as unchanged 
'   so that they will not be added to the db   
'   but start tracking changes to the entities
db.Topics.Attach(topic)

'   Remove the subscription
'   EF will know that the subscription should be removed from the topic
topic.subscriptions.Remove(subscription)

'   commit the changes
db.SaveChanges()

＆＃34;附加＆＃34;似乎不可用于导航属性集合

1 个答案: