How can I map the results of a sql query onto objects?

Question

Currently, I am using something like this:

    try
    {
      dr = SQL.Execute(sql);

      if(dr != null) {
         while(dr.Read()) {
           CustomObject         


        

Answer 1

One simple solution would be to make a constructor for your CustomObject that takes a DataRow (from the example, so if it's another class, please correct me).

And in your new constructor, do as you do in your own example.

public CustomObject(DataRow row)
{
    Key = row[0].ToString();
    // And so on...
}

One other way would be to introduce generics, and make a new function in your SQL-class

Example (Took code from Passing arguments to C# generic new() of templated type):

// This function should reside in your SQL-class.
public IEnumerable ExecuteObject(string sql)
{
    List items = new List();
    var data = ExecuteDataTable(sql); // You probably need to build a ExecuteDataTable for your SQL-class.
    foreach(var row in data.Rows)
    {
        T item = (T)Activator.CreateInstance(typeof(T), row);
        items.Add(item);
    }
    return items;
}

Example usage:

public IEnumerable GetCustomObjects()
{
    return SQL.ExecuteObject("SELECT * FROM CustomObject");
}

I have tested this code in LinqPad, it should work.