关系对象映射C＃

Question

What is the best way to map relational table which has more than 150 columns. I don't want to use any 3rd party or entity framework. if i am using data-reader it is very hard to write all the columns and convert it to relevant type.

Is there any easy way to do it or is this the only way?

 SqlDataReader _dr = _sqlCom.ExecuteReader() ;

        Info inObj= new Info ();


        while (_dr.Read())
        {

            inObj.a=  (int)_dr["a"];
            inObj.b= (int)_dr["b"];
            inObj.c= (int)_dr["c"];
            inObj.d= (int)_dr["d"];
            inObj.e= (int)_dr["e"];
            .....

            ......
        }

Answer 1

You could use reflection, if you're OK with incurring the performance hit. Something like this should work:

SqlDataReader reader = ...;
var propertyMappings = typeof (Info).GetProperties(BindingFlags.Instance | BindingFlags.Public)
    .Select(p => new {Property = p, Ordinal = reader.GetOrdinal(p.Name)})
    .ToList();
while (reader.Read())
{
    var info = new Info();
    foreach (var propertyMapping in propertyMappings)
        propertyMapping.Property.SetValue(info, reader[propertyMapping.Ordinal]);
}

Answer 2

If you want it done for you, you'll need to either use an ORM, there are some good ones out there, like Dapper , or use reflection (but will be slower). Otherwise you need to handle it all yourself. However instead of the ugly casting, you could write a few more lines of code to get rid of the casting, and would probably perform better

SqlDataReader _dr = _sqlCom.ExecuteReader() ;


Info inObj = new Info();

if (!_dr.HasRows) { return; }

int aPosition = _dr.GetOrdinal("a");}
int bPosition = _dr.GetOrdinal("b");
int cPosition = _dr.GetOrdinal("c");
int dPosition = _dr.GetOrdinal("d");
int ePosition = _dr.GetOrdinal("e");

while (_dr.Read())
{
    inObj.a = _dr.GetInt32(aPosition);
    inObj.b = _dr.GetInt32(bPosition);
    inObj.c = _dr.GetInt32(cPosition);
    inObj.d = _dr.GetInt32(dPosition);
    inObj.e = _dr.GetInt32(ePosition);

    .....

    ......
}