c# – 如何在子集合的Nhibernate中执行QueryOver

您好我有一个名为Notifications的类,它是User的子类.

public class User
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string UserName { get; set; }
    public ICollection<UserNotification> UserNotifications { get; set; }
}

public class Notification
{
    public int Id { get; set; }
    public ICollection<UserNotification> UserNotifications { get; set; }
    public string Title { get; set; }
    public string Message { get; set; }
    public bool IsRead { get; set; }
    public DateTime CreatedDate { get; set; }
}

public class UserNotification
{
    public User User { get; set; }
    public Notification Notification { get; set; }
}

现在我想获取User By ID,它将为当前用户提供所有通知.

var user = NhSession.Get<User>(userId);

但我不想收到所有通知.我只想让用户获得未读通知,并且只想获得用户的前5(最新)通知.

我尝试通过joinQueryOver实现这一点,但我无法做到这一点.任何人都可以建议让这个工作.

解决方法:

基于最新的更新和新的Entity(ies)结构,我们现在可以从Pairing对象中获利,并快速选择具有未读Notificaitons的用户

查找尚未阅读通知的用户

var session = NHSession.GetCurrent();
Notification notification = null;
UserNotification pair = null;
User user = null;

var subquery = QueryOver.Of<UserNotification>(() => pair)
    // this will give us access to notification
    // see we can filter only these which are NOT read
    .JoinQueryOver(() => pair.Notification, () => notification)
    // here is the filter
    .Where(() => !notification.IsRead)
    // now the trick to take only related to our user
    .Where(() => pair.User.Id == user.Id)
    // and get the user Id
    .Select(x => pair.User.Id);

var listOfUsers = session.QueryOver<User>(() => user)
    .WithSubquery
        .WhereProperty(() => user.Id)
        .In(subquery)
    // paging
    .Take(10)
    .Skip(10)
    .List<User>();

每个userId查找5个未读通知

var userId = 1;
var subqueryByUser = QueryOver.Of<UserNotification>(() => pair)
    // now we do not need any kind of a join 
    // just have to filter these pairs related to user
    .Where(() => pair.User.Id == userId)
    // and get the notification Id
    .Select(x => pair.Notification.Id);

var notificationsPerUser = session.QueryOver<Notification>(() => notification)
    .WithSubquery
        .WhereProperty(() => notification.Id)
        .In(subqueryByUser)
    .Where(() => !notification.IsRead)
    // if needed we can order
    // .OrderBy(...
    .Take(5)
    .List<Notification>()

标签：c,nhibernate,queryover
来源： https://codeday.me/bug/20190609/1206521.html