Question

Let’s say I have many-to-many relationship (using the ActiveRecord attribute HasAndBelongsToMany) between Posts and Tags (domain object names changed to protect the innocent), and I wanted a method like

FindAllPostByTags(IList<Tag> tags)

that returns all Posts that have all (not just some of) the Tags in the parameter. Any way I could accomplish this either with NHibernate Expressions or HQL? I’ve searched through the HQL documentation and couldn’t find anything that suited my needs. I hope I’m just missing something obvious!

Answer 1

You could also just use an IN statement

DetachedCriteria query = DetachedCriteria.For<Post>(); query.CreateCriteria('Post').Add(Expression.In('TagName',  string.Join(',',tags.ToArray()) ); 

I haven’t compiled that so it could have errors