How can I refactor these 2 methods into 1?

Question

I am trying to refactor some Entity Framework code where I have a Products entity and related entities for the Product's series, family, brand, etc. The series, family, and brand entities all have the same basic structure with an Id and Text property.

The two methods below are very similar and should be able to be refactored to a single method, but I'm not sure how to dynamically pass in which entity I'm querying from. In this case I need to be able to pass in db.ProductFamilies, or db.ProductSeriesSet. Any ideas how to make these 2 become 1?

Thanks!

    public DTOs.ProductCollection GetFamily(int id)
    {
        using (Entities db = new Entities())
        {
            var fam = (from collection in db.ProductFamilies.Include("Product")
                        .Include("Product.Stuff1")
                        .Include("Product.Stuff2")
                       where collection.Id == id
                       select collection).FirstOrDefault();
            return ProductCollectionEFToProductCollectionDTO(fam, true);
        }
    }

    public DTOs.ProductCollection GetSeries(int id)
    {
        using (Entities db = new Entities())
        {
            var ser = (from collection in db.ProductSeriesSet.Include("Product")
                        .Include("Product.Stuff1")
                        .Include("Product.Stuff2")
                       where collection.Id == id
                       select collection).FirstOrDefault();
            return ProductCollectionEFToProductCollectionDTO(ser, true);
        }
    }

Answer 1

If db.ProductFamilies and db.ProductSeriesSet are inherited from the same base class, then when you use ProductCollectionEFToProductCollectionDTO(BaseClass obj, bool value );

Or think about Generic type.

Those are two basic approaches.

Answer 2

You could use a Func<T, TResult> to delegate the selection of the good entity collection to the caller:

public DTOs.ProductCollection Get(int id, Func<Entities, XXX> selector)
{
    using (Entities db = new Entities())
    {
        var result = (from collection in selector(db).Include("Product")
                    .Include("Product.Stuff1")
                    .Include("Product.Stuff2")
                   where collection.Id == id
                   select collection).FirstOrDefault();
        return ProductCollectionEFToProductCollectionDTO(result, true);
    }
}

Here, XXX is of type of db.ProductFamilies and db.ProductSeriesSet.

You can then call it like that:

Get(42, db => db.ProductFamilies);
Get(12, db => db.ProductSeriesSet);

Does it work?