Wrapping multiple queries with multiple outputs

Question

Wrapping multiple queries with multiple outputs

c# dapper generics refactoring sql

Question

I have this class, in which I am wrapping dapper calls in order to do something like

var results = SqlWrapper.ExecuteQuery<Product,Customer>("SELECT id FROM Products; SELECT id FROM Customers;");

Where

results[0] = List<Product>
results[1] = List<Customer>

I support 1,2,3 output objects, but would like arbitrary. The class is also ugly and full of copy and pasted code. I account for if I want to reuse a connection by optionally passing a connection but the code just seems unclean. What I would really like is a way to define params T[] but as I understand that doesnt work. Is this any way this code can be cleaned/shortened?

using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using Dapper;

namespace SqlWrapper
{
    public static class SqlWrapper
    {
        private const string SqlConnectionString = "Server=localhost;Database=TTDS;User Id=sa;Password=sa;";


        public static List<T> ExecuteQuery<T>(string sql, object param = null, SqlConnection sqlConnection = null)
        {
            if (sqlConnection != null)
            {
                return sqlConnection.Query<T>(sql, param).ToList();
            }

            using (var tempSqlConnection = new SqlConnection(SqlConnectionString))
            {
                tempSqlConnection.Open();
                return tempSqlConnection.Query<T>(sql, param).ToList();
            }
        }


        public static List<dynamic> ExecuteQuery<T1, T2>(string sql, object param = null, SqlConnection sqlConnection = null)
        {
            if (sqlConnection != null)
            {
                return MultiQuery<T1, T2>(sqlConnection, sql, param);
            }

            using (var tempSqlConnection = new SqlConnection(SqlConnectionString))
            {
                return MultiQuery<T1, T2>(tempSqlConnection, sql, param);
            }
        }

        public static List<dynamic> ExecuteQuery<T1, T2, T3>(string sql, object param = null,
            SqlConnection sqlConnection = null)
        {
            if (sqlConnection != null)
            {
                return MultiQuery<T1, T2, T3>(sqlConnection, sql, param);
            }

            using (var tempSqlConnection = new SqlConnection(SqlConnectionString))
            {
                return MultiQuery<T1, T2, T3>(tempSqlConnection, sql, param);
            }
        }

        private static List<dynamic> MultiQuery<T1, T2>(SqlConnection sqlConnection, string sql, object param = null)
        {
            var rv = new List<dynamic>();

            using (var grid = sqlConnection.QueryMultiple(sql, param))
            {
                rv.Add(grid.Read<T1>().ToList());
                rv.Add(grid.Read<T2>().ToList());
            }

            return rv;
        }

        private static List<dynamic> MultiQuery<T1, T2, T3>(SqlConnection sqlConnection, string sql, object param = null)
        {
            var rv = new List<dynamic>();

            using (var grid = sqlConnection.QueryMultiple(sql, param))
            {
                rv.Add(grid.Read<T1>().ToList());
                rv.Add(grid.Read<T2>().ToList());
                rv.Add(grid.Read<T3>().ToList());
            }

            return rv;
        }


        public static void ExecuteNonQuery(SqlConnection sqlConnection, string sql, object param, int? timeout = null)
        {
            if (sqlConnection != null)
            {
                sqlConnection.Execute(sql, param, commandTimeout: timeout);
            }
            else
            {
                using (var tempSqlConnection = new SqlConnection(SqlConnectionString))
                {
                    tempSqlConnection.Open();
                    tempSqlConnection.Execute(sql, param, commandTimeout: timeout);
                }
            }
        }
    }
}

ParoX

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Grax32 · Accepted Answer · 10/13/2015 4:25:30 AM

Here is some untested code that demonstrates a couple of ideas that I had.

While "using" is pretty awesome, you can pare down your code some if you optionally create the connection first and then, if necessary, dispose the sqlConnection in a finally block.
If you return a Tuple<List<T>,List<U>,List<V>> you can have strongly typed return values that you can easily use
If you call your most complex function from those that are less complex, you can minimize your duplicated code.

public static class SqlWrapper
{
    private const string SqlConnectionString = "Server=localhost;Database=TTDS;User Id=sa;Password=sa;";

    private class NoResult { }

    public static List<T1> ExecuteQuery<T1>(string sql, object param = null, SqlConnection sqlConnection = null)
    {
        return ExecuteQuery<T1, NoResult, NoResult>(sql, param, sqlConnection).Item1;
    }

    public static Tuple<List<T1>, List<T2>> ExecuteQuery<T1, T2>(string sql, object param = null, SqlConnection sqlConnection = null)
    {
        var result = ExecuteQuery<T1, T2, NoResult>(sql, param, sqlConnection);
        return Tuple.Create(result.Item1, result.Item2);
    }

    public static Tuple<List<T1>, List<T2>, List<T3>> ExecuteQuery<T1, T2, T3>(string sql, object param = null, SqlConnection sqlConnection = null)
    {
        List<T1> list1;
        List<T2> list2 = null;
        List<T3> list3 = null;
        bool needsDisposed = false;

        if (sqlConnection == null)
        {
            sqlConnection = new SqlConnection(SqlConnectionString);
            sqlConnection.Open();
            needsDisposed = true;
        }

        try
        {
            using (var grid = sqlConnection.QueryMultiple(sql, param))
            {
                list1 = grid.Read<T1>().ToList();
                if (typeof(T2) != typeof(NoResult))
                {
                    list2 = grid.Read<T2>().ToList();
                }
                if (typeof(T3) != typeof(NoResult))
                {
                    list3 = grid.Read<T3>().ToList();
                }

                return Tuple.Create(list1, list2, list3);
            }
        }
        finally { if (needsDisposed) sqlConnection.Dispose(); }
    }


    public static void ExecuteNonQuery(SqlConnection sqlConnection, string sql, object param, int? timeout = null)
    {
        bool needsDisposed = false;

        if (sqlConnection == null)
        {
            sqlConnection = new SqlConnection(SqlConnectionString);
            sqlConnection.Open();
            needsDisposed = true;
        }

        try { sqlConnection.Execute(sql, param, commandTimeout: timeout); }
        finally { if (needsDisposed) sqlConnection.Dispose(); }
    }
}

Wrapping multiple queries with multiple outputs

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