Using LINQ and Entity how do I return values of a many-to-many relationship

问题

I have two entities, Account and Subscription with a many-to-many association between them. I can't seem to find in the tutorials anywhere how to do the following:

I want to find all the Accounts with a Subscription of type x. If I wasn't using the Entity framework I could join to the AccountSubscription table, but that isn't accessible via Entity. Do I have to create a special entity if I need to query on a many-to-many relationship?

回答1:

EF should create a navigation property for a many-to-many relationship. Then you should be able to do something like this:

var accounts = from a in Accounts
               where a.Subscriptions.Any(s => s.SubscriptionType == "something")
               select a;

For example, I have a simple db with a many to many relationship between Products and Groups:

And EF creates the association in the model:

So I can create a query like this (here including the Groups so I can see the Category):

回答2:

What about something like this:

List<Accounts> myAccounts = //get accounts;

foreach(Accounts a in myAccounts)
{
  foreach(Subscriptions s in a)
  {
     //add it to a global list?
  } 
}

来源：https://stackoverflow.com/questions/4235978/using-linq-and-entity-how-do-i-return-values-of-a-many-to-many-relationship