When an object-relational mapper is too much, DataReader too little

I fired up Visual Studio this evening to write a proof-of-concept app and found myself wanting strongly typed domain objects from a database but without the overhead of an object-relational mapper  (the application is read-only).

One solution is to write methods by hand, another is to code generate them but it would be nice to be able to do:

var customers = new SqlCommand("SELECT ID, Name FROM Customer", connection)
  .As(r => new Customer { CustomerID = r.GetInt32(0), Name = r.GetString(1) }).ToList();

So for any DbCommand object you can turn it into a bunch of classes by specifying the new pattern.

The tiny helper class to achieve this is:

public static class DataHelpers {
  public static List<T> ToList<T>(this IEnumerable<T> enumerable) {
    return new List<T>(enumerable);
  }

  public static IEnumerable<T> As<T>(this DbCommand command, Func<IDataRecord, T> map) {
    using (var reader = command.ExecuteReader())
      while (reader.Read())
        yield return map(reader);
  }
}

It might even be possible to do some cool caching/materialization. I should look into that :)

[)amien