Subqueries with QueryOver

Question

I have a issue in using subquery with queryover.

This is what I have

      var address = QueryOver.Of<Address>()
            .Where(x => x.City.IsLike("%" + city + "%")).Select(x => x.Person.Id);

        var result = Session.QueryOver<Person>()
            .Where(x => x.Type.IsLike(type + "%"))
            .And(x => x.Name.IsLike("%" + name + "%"))
            .WithSubquery.WhereExists(address);

I have a table for Person and a person has multiple addreses.

So Person id, name, type

and Address will have PersonId and city etc.

So want to search a person by name and type as well as City which is in Address table

Answer 1

Try something like this:

Address address = null;
Person person = null;
var addressSubQuery = QueryOver.Of<Address>(() => address)
    .Where(Restrictions.EqProperty(Projections.Property(() => address.Person.Id), Projections.Property(() => person.Id)))
    .Where(() => address.City.IsLike("%" + city + "%"));

    var result = Session.QueryOver<Person>(() => person)
        .Where(x => x.Type.IsLike(type + "%"))
        .And(x => x.Name.IsLike("%" + name + "%"))
        .WithSubquery.WhereExists(addressSubQuery);

You need to use QueryOver's version of aliasing. This way you can reference the Person element from other queries which you will eventually link into your main query.

This is the same as doing something like the following

Select * from Person
Where 
    Type like '%foo%'
    and Name like '%bar%'
    and exists ( select Id from Address 
                 where 
                      Address.PersonId = Person.Id
                      and Address.City like '%bar%' )