问题
I have two entities which are:
User
{
UserGuid,
Address,
.
.
.
EmailCount // This is not a column in the database,
// I just wanna get the count number from the UserEmail table
// and map the value to this property
}
UserEmail
{
UserGuid,
Timestamp
}
The issue is how can I get the email count with a sub query in NHibernate?
By far I have this, but it does not work. Any idea?
User userEntity = null;
var subQuery = QueryOver.Of<UserEmail>()
.Where(ue => ue.UserGuid == userEntity.UserGuid)
.ToRowCountQuery();
return _session.StatefulSession.QueryOver(() => userEntity)
.WithSubquery.WhereValue("EmailCount").Eq(subQuery)
.List();
回答1:
This would be the way how to use subquery
to get an inlined count with a QueryOver
syntax:
User userEntity = null;
var subQuery = QueryOver
.Of<UserEmail>()
.Where(ue => ue.UserGuid == userEntity.UserGuid)
.ToRowCountQuery();
var list = _session.StatefulSession
.QueryOver<User>(() => userEntity)
.SelectList(projections => projections
.Select(x => x.UserGuid)
.WithAlias(() => userEntity.UserGuid)
.Select(x => x.Address)
.WithAlias(() => userEntity.Address)
// any property to be selected
...
// INLINE COUNT
// our subquery placed into play
.SelectSubQuery(subQuery)
// this will populate virtual/not mapped EmailCount
.WithAlias(() => userEntity.EmailCount)
)
.TransformUsing(Transformers.AliasToBean<User>())
//.Take(10).Skip(100) // paging
.List();
来源:https://stackoverflow.com/questions/24513919/nhibernate-count-another-entity-with-sub-query