Using impatient download with spec template

Question

I implemented a specification template with Linq as described here https://www.packtpub.com/article/nhibernate-3-using-linq-specifications-data-access-layer

Now I want to add the ability to download and do not know how best to do it.

Generic repository class in a related example:

public IEnumerable<T> FindAll(Specification<T> specification)
{
  var query = GetQuery(specification);
  return Transact(() => query.ToList());
}

public T FindOne(Specification<T> specification)
{
  var query = GetQuery(specification);
  return Transact(() => query.SingleOrDefault());
}

private IQueryable<T> GetQuery(
  Specification<T> specification)
{
  return session.Query<T>()
    .Where(specification.IsSatisfiedBy());
}

And the specification implementation:

public class MoviesDirectedBy : Specification<Movie>
{

 private readonly string _director;

 public MoviesDirectedBy(string director)
 {
   _director = director;
 }

 public override
    Expression<Func<Movie, bool>> IsSatisfiedBy()
 {
   return m => m.Director == _director;
 }
}

This works well, now I want to add the ability to be able to download. I understand that loading NHibernate can be done using Fetch in the request.

I am looking for whether to encapsulate the logic of a loadable load into a specification or pass it to a repository, as well as the syntax of the Linq / expression tree needed to achieve this (for example, an example of how this will be done).

Answer 1

Specification :

public virtual IEnumerable<Expression<Func<T, object>>> FetchRelated
{
    get
    {
        return Enumerable.Empty<Expression<Func<T, object>>>();
    }
}

GetQuery - :

        return specification.FetchRelated.Aggregate(
            session.Query<T>().Where(specification.IsSatisfiedBy()),
            (current, related) => current.Fetch(related));

, , FetchRelated

public override IEnumerable<Expression<Func<Movie, object>>> FetchRelated
{
    get
    {
        return new Expression<Func<Movie, object>>[]
                     {
                         m => m.RelatedEntity1,
                         m => m.RelatedEntity2
                     };
    }
}

, , , , .

( ThenFetch), ( object, )

Answer 2

Fetch() , . , , , , Fetch.