Generic QueryMultiple with Dapper

Question

I have a base repository with a Generic Get method to return Data using Dapper like

  public T Get(Func query)
    {
                


        

Answer 1

You could do something like this which will return a tuple containing IEnumerables of each type you are after.

In Base Repository

(It's basically a bunch of overloads...you can add more overloads if you have more types).

public Tuple<IEnumerable<T1>, IEnumerable<T2>> GetMultiple<T1, T2>(string sql, object parameters,
                                        Func<GridReader, IEnumerable<T1>> func1,
                                        Func<GridReader, IEnumerable<T2>> func2)
        {
            var objs = getMultiple(sql, parameters, func1, func2);
            return Tuple.Create(objs[0] as IEnumerable<T1>, objs[1] as IEnumerable<T2>);
        }

        public Tuple<IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>> GetMultiple<T1, T2, T3>(string sql, object parameters,
                                        Func<GridReader, IEnumerable<T1>> func1,
                                        Func<GridReader, IEnumerable<T2>> func2,
                                        Func<GridReader, IEnumerable<T3>> func3)
        {
            var objs = getMultiple(sql, parameters, func1, func2, func3);
            return Tuple.Create(objs[0] as IEnumerable<T1>, objs[1] as IEnumerable<T2>, objs[2] as IEnumerable<T3>);
        }

        private List<object> getMultiple(string sql, object parameters,params Func<GridReader,object>[] readerFuncs )
        {
            var returnResults = new List<object>();
            using (IDbConnection db = new SqlConnection(ConfigurationManager.ConnectionStrings["myDB"].ConnectionString))
            {
                var gridReader = db.QueryMultiple(sql, parameters);

                foreach(var readerFunc in readerFuncs)
                {
                    var obj = readerFunc(gridReader);
                    returnResults.Add(obj);
                }
            }

            return returnResults;
        }

In Derived Repository

(pretty clean and more importantly, typed!)

public class Foo { }

        public class Bar { }

        public void sample()
        {
            var sql = "select * from Foo; select * from Bar";
            var foosAndBars = this.GetMultiple(sql, new { param = "baz" }, gr => gr.Read<Foo>(), gr => gr.Read<Bar>());
            var foos = foosAndBars.Item1;
            var bars = foosAndBars.Item2;
        }