无法解析属性: PropertyName of: NHibernate中的类错误

Question

我第一次使用NHibernate，在这一行中它为我抛出异常

var total = session
                    .QueryOver<Comment>().Where(p => p.Entry.Author == username)
                    .ToRowCountQuery()
                    .FutureValue<int>();

                var results = session
                    .QueryOver<Comment>().Where(p => p.Entry.Author == username)
                    .Fetch(x => x.Entry).Eager()
                    .OrderBy(x => x.Posted).Desc()
                    .Skip(skip)
                    .Take(take)
                    .List();

例外是

无法解析属性: Entry.Author of: FunnelWeb.Model.Comment

我想问题是Entry对象在这里没有加载。我怎么才能用Nhibernate来耍这个把戏呢？

Answer 1

QueryOver只是标准的强类型包装器，不允许隐式深度引用。

你得用：

session.QueryOver<Comment>()
       .JoinQueryOver(x => x.Entry)
       .Where(x => x.Author == username)

或者您可以使用Query<> (LINQ)，它将与您尝试过的语法一起工作。

Answer 2

你需要JoinAlias或JoinQueryOver。下面有一个关于如何使用未来查询的例子.

Entry entryAlias = null;

var q = session.QueryOver<Comment>()
    .JoinAlias(x => x.Entry, () => entryAlias)
    .Where(() => entryAlias.Author == username);

var totalFuture = q.ToRowCountQuery().FutureValue<int>(); //ToRowcountQuery clones the query, we can reuse it for results

var resultsFuture = q
    //.Fetch(x => x.Entry).Eager() //already joined
    .OrderBy(x => x.Posted).Desc()
    .Skip(skip)
    .Take(take)
    .Future<Comment>();

var results = resultsFuture.ToList(); //both future queries are executed in the same batch 
var total = totalFuture.Value;