Question

有人能指出一个示例或简要描述如何使用Linq to SQL 作为数据访问层创建WCF RIA Services DomainService的自定义实现，但是没有使用.dbml 文件（这是因为Linq to SQL模型是由自定义工具生成的，是大量切割的，并且是一个包含50多个表的相当大的数据库）和没有VS2010用于创建DomainService的向导（该向导依赖于.dbml文件可用）

这是我迄今为止尝试过的一个非常简单的外壳：

[EnableClientAccess()] public class SubscriptionService : DomainService { [Query(IsDefault = true)] public IQueryable<Subscription> GetSubscriptionList() { SubscriptionDataContext dc = new SubscriptionDataContext(); var subs = dc.Subscription.Where(x => x.Status == STATUS.Active) .Select(x => new Subscription { ID = x.ID, Name = x.Name }).ToList(); return subs.AsQueryable(); } public void InsertSubscription(Subscription sub) { if (!sub.ID.IsEmpty()) { SubscriptionDataContext dc = new SubscriptionDataContext(); Subscription tmpSub = dc.GetByID<Subscription>(sub.ID); if (tmpSub != null) { tmpSub.Name = sub.Name; dc.Save(tmpSub); } else { tmpSub = new Subscription(); tmpSub.Name = sub.Name; dc.Save(tmpSub); } } } public void UpdateSubscription(Subscription sub) { if (!sub.ID.IsEmpty()) { SubscriptionDataContext dc = new SubscriptionDataContext(); Subscription tmpSub = dc.GetByID<Subscription>(sub.ID); if (tmpSub != null) { tmpSub.Name = sub.Name; dc.Save(tmpSub); } } } public void DeleteSubscription(Subscription sub) { if (!sub.ID.IsEmpty()) { SubscriptionDataContext dc = new SubscriptionDataContext(); Subscription tmpSub = dc.GetByID<Subscription>(sub.ID); if (tmpSub != null) { dc.Delete(tmpSub); } } } }

到目前为止这似乎有效。有没有人看到我可能会遗漏这种方法的任何问题？如果有人已经尝试过这种方式并且发现了一些重大问题，我不想在这个错误的道路上走太远。

感谢大家的投入。

Answer 1

这样做是没有错的。

我基本上做了同样的事情。

您需要创建一个为每个查询返回IQueryable的属性，然后您将自动神奇地获取使用RIA服务的skip / take / where。

[EnableClientAccess()]
public class SubscriptionService : DomainService
{
    [Query(IsDefault = true)]
    public IQueryable<Subscription> GetSubscriptionList()
    {
        using(var dc = new SubscriptionDataContext())
             return from x in dc.Subscription
                    where x.Status == STATUS.Active
                    select new Subscription { ID = x.ID, Name = x.Name };
        // make sure you don't call .ToList().AsQueryable() 
        // as you will basically load everything into memory, 
        // which you don't want to do if the client is going to be using 
        // any of the skip/take/where features of RIA Services.  
        // If you don't want to allow this, 
        // simply return an IEnumerable<Subscription>
    }
 }

我假设Subscription是DTO而不是L2S类，因为您明确地实例化它。只需确保您的DTO具有正确的属性。即。

public class Subscription
{
    [Key]
    // you must have a key attribute on one or more properties...
    public int ID { get; set; }
}

如果您的DTO中有子元素，请使用Include和Association属性：

public class User
{
    [Key]
    public int Id { get; set; }

    [Include]
    [Association("User_Subscriptions", "Id","UserId")]
    // 'Id' is this classes's Id property, and 'UserId' is on Subscription
    // 'User_Subscriptions' must be unique within your domain service,
    // or you will get some odd errors when the client tries to deserialize
    // the object graph.
    public IEnumerable<Subscription> Subscriptions { get; set; }
}

另外作为旁注，你不需要删除方法的完整对象，这样的东西会起作用，并且会阻止客户端序列化整个对象，并在你不需要时将其发回。 / p>

public void DeleteSubscription(int id)
{
    using(var dc = new SubscriptionDataContext())
    {
        var sub = dc.GetById<Subscription>(id);
        if( sub != null ) dc.Delete(sub);
    }
}

使用Linq to SQL自定义实现DomainService

1 个答案: