Oracle bulk insert for Dapper .NET

bulk.cs

        private static int OracleBulkExecuteImpl<T>(this IDbConnection cnn, ref CommandDefinition command)
        {
            object param = command.Parameters;
            IEnumerable multiExec = GetMultiExec(param);
            Identity identity;
            CacheInfo info = null;
            if (multiExec != null)
            {
                int total = 0;
                bool wasClosed = cnn.State == ConnectionState.Closed;
                try
                {
                    if (wasClosed) cnn.Open();
                    using (var cmd = command.SetupCommand(cnn, null) as OracleCommand)
                    {
                        var dataList = multiExec.Cast<T>();
                                                
                        cmd.ArrayBindCount = dataList.Count();
                        cmd.Parameters.Clear();

                        foreach (var prop in typeof(T).GetProperties())
                        {
                            var data = dataList.Select(x => prop.GetValue(x));
                            var propType = Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType;

                            if (propType == typeof(int))
                            {
                                cmd.Parameters.Add(":" + prop.Name, data.Cast<int>().ToArray());
                            }
                            else if (propType == typeof(DateTime))
                            {
                                cmd.Parameters.Add(":" + prop.Name, data.Cast<DateTime>().ToArray());
                            }
                            else if (propType == typeof(string))
                            {
                                cmd.Parameters.Add(":" + prop.Name, data.Cast<string>().ToArray());
                            }
                            else if (propType == typeof(double))
                            {
                                cmd.Parameters.Add(":" + prop.Name, data.Cast<double>().ToArray());
                            }
                            else
                            {
                                throw new ArgumentNullException("Unknown data type");
                            }
                        }
                        total = cmd.ExecuteNonQuery();
                    }                    
                    command.OnCompleted();
                }
                finally
                {
                    if (wasClosed) cnn.Close();
                }
                return total;
            }

            // nice and simple
            if (param != null)
            {
                identity = new Identity(command.CommandText, command.CommandType, cnn, null, param.GetType(), null);
                info = GetCacheInfo(identity, param, command.AddToCache);
            }
            return ExecuteCommand(cnn, ref command, param == null ? null : info.ParamReader);
        }