服务结构演员状态和列表

Question

建议在服务结构演员中有一个列表吗？我正在尝试将用户收藏夹保存在用户演员中。这种情况下最好的方法是什么？

Answer 1

是的，只要您将列表视为不可变的。

状态管理器检索方法返回对本地内存中对象的引用。仅在本地存储器中修改此对象不会导致它被长期保存，因此不会被 保存。从 状态管理器中检索并修改对象时，必须将其重新插入状态为 的管理器，以便持久保存。

-

以下用户信息类型演示了如何定义一个不可变型 采取的上述建议的优势。

[DataContract] 
// If you don’t seal, you must ensure that any derived classes are also immutable 
public sealed class UserInfo { 
    private static readonly IEnumerable<ItemId> NoBids = ImmutableList<ItemId>.Empty; 

    public UserInfo(String email, IEnumerable<ItemId> itemsBidding = null) { 
     Email = email; 
     ItemsBidding = (itemsBidding == null) ? NoBids : itemsBidding.ToImmutableList(); 
    } 

    [OnDeserialized] 
    private void OnDeserialized(StreamingContext context) { 
     // Convert the deserialized collection to an immutable collection 
     ItemsBidding = ItemsBidding.ToImmutableList(); 
    } 

    [DataMember] 
    public readonly String Email; 

    // Ideally, this would be a readonly field but it can't be because OnDeserialized 
    // has to set it. So instead, the getter is public and the setter is private. 
    [DataMember] 
    public IEnumerable<ItemId> ItemsBidding { get; private set; } 

    // Since each UserInfo object is immutable, we add a new ItemId to the ItemsBidding 
    // collection by creating a new immutable UserInfo object with the added ItemId. 
    public UserInfo AddItemBidding(ItemId itemId) { 
     return new UserInfo(Email, ((ImmutableList<ItemId>)ItemsBidding).Add(itemId)); 
    } 
} 

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