How to get a distinct result with nHibernate and QueryOver API?
I have this Repository method
public IList<Message> ListMessagesBy(string text, IList<Tag> tags, int pageIndex, out int count, out int pageSize)
{
pageSize = 10;
var likeString = string.Format("%{0}%", text);
var query = session.QueryOver<Message>()
.Where(Restrictions.On<Message>(m => m.Text).IsLike(likeString) ||
Restrictions.On<Message>(m => m.Fullname).IsLike(likeString));
if (tags.Count > 0)
{
var tagIds = tags.Select(t => t.Id).ToList();
query
.JoinQueryOver<Tag>(m => m.Tags)
.WhereRestrictionOn(t => t.Id).IsInG(tagIds);
}
count = 0;
if(pageIndex < 0)
{
count = query.ToRowCountQuery().FutureValue<int>().Value;
pageIndex = 0;
}
return query.OrderBy(m => m.Created).Desc.Skip(pageIndex * pageSize).Take(pageSize).List();
}
You supply a free text search string and a list of Tags. The problem is that if a message has more then one tag it is listed duplicated times. I want a distinct result based on the Message entity. I've looked at
Projections.Distinct
But it requires a list of Properties to to the distinct question on. This Message is my entity root there most be a way of getting this behaviour without supplying all of the entity properties?
Thanks in advance, Anders
If you're using the ICriteria API, you need:
.SetResultTransformer(new DistinctEntityRootTransformer())
If you're using the QueryOver API, you need:
.TransformUsing(Transformers.DistinctRootEntity)
But beware, this all occurs on client side, so all the duplicate rows are still pulled.
Try something like this
public IPagedList<Client> Find(int pageIndex, int pageSize)
{
Client clientAlias = null;
var query = Session.QueryOver<Client>(() => clientAlias)
.Select(
Projections.Distinct(
Projections.ProjectionList()
.Add(Projections.Property<Client>(x => x.Id).As("Id"))
.Add(Projections.Property<Client>(x => x.Name).As("Name"))
.Add(Projections.Property<Client>(x => x.Surname).As("Surname"))
.Add(Projections.Property<Client>(x => x.GivenName).As("GivenName"))
.Add(Projections.Property<Client>(x => x.EmailAddress).As("EmailAddress"))
.Add(Projections.Property<Client>(x => x.MobilePhone).As("MobilePhone"))
)
)
.TransformUsing(Transformers.AliasToBean<Client>())
.OrderBy(() => clientAlias.Surname).Asc
.ThenBy(() => clientAlias.GivenName).Asc;
var count = query
.ToRowCountQuery()
.FutureValue<int>();
return query
.Take(pageSize)
.Skip(Pagination.FirstResult(pageIndex, pageSize))
.List<Client>()
.ToPagedList(pageIndex, pageSize, count.Value);
}