Add multiple included dynamically - entity-framework-6

Question

I put together some helpers that will allow me to register includes by type. Looks like this:
Dictionary<Type, LambdaExpression[]> includes =
new Dictionary<Type, LambdaExpression[]>();
I register includes like this:
public void Add<T>(params Expression<Func<T, object>>[] includes)
{
this.includes.Add(typeof(T), includes);
}
Add<Customer>(e =>
e.Address.City.Province.Country,
e.Products.Select(p => p.Category));
Notice there are two includes for Customer. I then have this method that gets includes by type:
DbSet<T> entitySet = null;
void LoadIncludes()
{
var includes = Includes.Instance.Get<T>().DirectCast<Expression<Func<T, object>>[]>();
if (includes != null)
{
foreach (var include in includes)
{
entitySet.Include(include).Load();
}
}
}
When getting my entity, I do this:
public T GetById(int id)
{
LoadIncludes();
return entitySet.SingleOrDefault(x => x.Id == id);
}
It works well, but it's so slow, and it's because of the .Load() method I am calling in LoadIncludes(). Is there a faster way to do what I want to do here?

Answer 1

You shouldn't call Load, but build and use a Queryable<T> with Include chain.
Replace LoadIncludes with private function:
private IQueryable<T> GetEntitySet()
{
var set = entitySet.AsQueryable();
var includes = Includes.Instance.Get<T>().DirectCast<Expression<Func<T, object>>[]>();
if (includes != null)
{
foreach (var include in includes)
{
set = set.Include(include);
}
}
return set;
}
and use it as follows:
public T GetById(int id)
{
return GetEntitySet().SingleOrDefault(x => x.Id == id);
}