将IEnumerable转换为System.Data.Linq.Table

Question

I have a function whose return type is Table

This code does not work. I just want to return the IEnumerable as Linq.Table **

 public static System.Data.Linq.Table<Products> GetProducts()
    {
        MyContext mc = new MyContext();

        Table<Products> ret = null;
        // Or   Table<Products> ret = mc.GetTable<Products>();

        ret.AttachAll<Products>(mc.GetTable<Products>()
                                  .OrderBy(p => p.ProductID).Take(1));

        return ret;
    }

Now I want to cast IEnumerable query to System.Data.Linq.Table.

(You may say that I can change the return type but the question is whether this is possible. Can I override some function like GetTable()? )

Answer 1

You can't. The Table<TEntity> class exists in order to provide an IQueryable<T> interface implementation. There aren't any actual items in there, it's just a root that's exposed by the DataContext class in order to provide an IQueryable<T> implementation which is interpreted, translated to SQL and then sent to SQL server.

If you have an IEnumerable<T> interface implementation, chances are you already have the materialized result set (or an in-memory collection) that you are iterating over. There's no benefit to having an IQueryable<T> implementation because there's nothing to interpret; everything you want is already in memory.

That said, it's probably better to just use the regular extension methods/query syntax off your IEnumerable<T> implementation than trying to put it in a Table<TEntity> .