Nhibernate QueryOver how can I make this query use async?

Question

For this new website I want to use async methods in NHibernate. I have this simple query using QueryOver API but I can't get this one to work with async.

It is a simple query with some where clauses that list all businesses. I want 20 of them each time I execute this.

Query:

BusinessListItem bli = null;
BusinessCategory bc = null;
Category c = null;
BusinessImage bi = null;
Image i = null;

var q = Session.QueryOver<Business>()
            .JoinAlias(x => x.Categories, () => bc)
            .JoinAlias(() => bc.Category, () => c)
            .JoinAlias(x => x.Images, () => bi, JoinType.LeftOuterJoin)
            .JoinAlias(() => bi.Image, () => i, JoinType.LeftOuterJoin)
            .Where(() => bc.IsMain);

        if (!string.IsNullOrEmpty(_name))
            q.WhereRestrictionOn(x => x.Name).IsLike($"%{_name}%");

        if (!string.IsNullOrEmpty(_streetName))
            q.WhereRestrictionOn(x => x.StreetName).IsLike($"%{_streetName}%");

        if (_categoryId != null)
            q.Where(() => c.Id == _categoryId.Value);

        if (_subCategoryIds != null)
            q.WhereRestrictionOn(() => c.Id).IsIn(_subCategoryIds);

        return q.Select(
                Projections.Property<Business>(x => x.Id).WithAlias(() => bli.Id),
                Projections.Property<Business>(x => x.Name).WithAlias(() => bli.Name),
                Projections.Property("c.Name").WithAlias(() => bli.CategoryName),
                Projections.Property("bi.Image").WithAlias(() => bli.Image)
            )
            .TransformUsing(Transformers.AliasToBean<BusinessListItem>())
            .List<BusinessListItem>()
            .OrderBy(x => x.Name)
            .Skip(_skipCount)
            .Take(20)
            .ToList();

I know the method .ListAsync() exists but I cannot get it working together with the Skip, Take and OrderBy method.

Any help is much appreciated!

Answer 1

The solution to this question is :

var result = await q.Select(
                Projections.Distinct(
                    Projections.Property<Business>(x => x.Id).WithAlias(() => bli.Id)
            )
            .TransformUsing(Transformers.AliasToBean<BusinessListItem>())
            .OrderBy(x => x.Name).Asc
            .Skip(_skipCount)
            .Take(_takeCount)
            .ListAsync<BusinessListItem>();

        return result.ToList();

Thx to @DavidOsborne