DbContextExtensions.cs

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Reflection;
using Dapper;
using Microsoft.EntityFrameworkCore;

public static class DbContextExtensions {
  public static IQueryable<object> Set(this DbContext context, Type type) {
    return (IQueryable<object>)context.GetType().GetMethod("Set").MakeGenericMethod(type).Invoke(context, null);
  }

  public static IEnumerable<T> Query<T>(this DbContext context, string sql, object param = null, IDbTransaction transaction = null, bool buffered = true, int? commandTimeout = null, CommandType ? commandType = null) {
    return context.Database.GetDbConnection().Query<T>(sql, param, transaction, buffered, commandTimeout, commandType);
  }

  public static IEnumerable<dynamic> Query(this DbContext context, string sql, object param = null, IDbTransaction transaction = null, bool buffered = true, int? commandTimeout = null, CommandType? commandType = null) {
    return context.Database.GetDbConnection().Query(sql, param, transaction, buffered, commandTimeout, commandType);
  }
}

An extension method for getting DbSet results using a non-generic method, e.g. context.Set(typeof(Foo)). Should be just about as fast as a DbSet() call after the first usage for T.

Haha. Previous version blew on caching -- context was disposed. Here's the straight up version.

Added some methods for Dapper.