Dapper map multiple joins Sql Query

Question

I want to map complex object to dapper result from query which has two inner joins. I know we\'ve solution to map one inner join but I want to map two inner joins result.

<

Answer 1

I decided to use Dapper to get a big data for calculating somethings. This is my dapper extension method to join 3 table in _RepositoryBase.cs file.

    public List> QueryMultiple(string sql, object param)
        where T2 : class
        where T3 : class
    {
        using (var con = new SqlConnection(GetConnStr()))
        {
            if (con.State == ConnectionState.Closed)
                con.Open();

            var query = con.Query>(sql, (t, t2, t3, t4) => Tuple.Create(t, t2, t3, t4), param);

            //if (query.Count() == 0)
            //    return new List();

            var data = query.ToList();

            con.Close();
            con.Dispose();

            return data;
        }
    }

Then, this function will help you to get sql joined data via dapper.

    public List GetSqlJoinedDataViaDaper(int customerId)
    {
        var repo = new GenericRepository();
        var sql = @"select table1.ID Table1ID, table1.*,
                    table2.ID Table2ID, table2.*,
                    table3.ID Table3ID, table3.*
                    from dbo.Table1 table1 (nolock)
                    left outer join dbo.Table2 table2 (nolock) on table2.ID=table1.FKTable2ID
                    left outer join dbo.Table3 table3 (nolock) on table3.ID=table1.FKTable3ID
                    where table1.CustomerID=@p1 ";

        var resultWithJoin = repo.QueryMultiple(sql,
            new { p1 = 1, splitOn = "Table1ID,Table2ID,Table3ID" }).ToList();

        var retval = new List();
        foreach (var item in resultWithJoin)
        {
            Table1 t1 = item.Item2; //After first split
            t1.Table2 = item.Item3; //After Table2ID split
            t1.Table3 = item.Item4; //After Table3ID split

            retval.Add(t1);
        }
        return retval;
    }

Summary: Write your select and insert split between tables. Say splits to Dapper and get your data. I used this and worked better than Entity Framework.