Fastest way to map result of SqlDataReader to object

Question

I\'m comparing materialize time between Dapper and ADO.NET and Dapper. Ultimately, Dapper tend to faster than ADO.NET, though the first time a given fetch query was executed

Answer 1

This is based on the other answers but I used standard reflection to read the properties of the class you want to instantiate and fill it from the dataReader. You could also store the properties using a dictionary persisted b/w reads.

Initialize a dictionary containing the properties from the type with their names as the keys.

var type = typeof(Foo);
var properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
var propertyDictionary = new Dictionary();
foreach(var property in properties)
{
    if (!property.CanWrite) continue;
    propertyDictionary.Add(property.Name, property);
}

The method to set a new instance of the type from the DataReader would be like:

var foo = new Foo();
//retrieve the propertyDictionary for the type
for (var i = 0; i < dataReader.FieldCount; i++)
{
    var n = dataReader.GetName(i);
    PropertyInfo prop;
    if (!propertyDictionary.TryGetValue(n, out prop)) continue;
    var val = dataReader.IsDBNull(i) ? null : dataReader.GetValue(i);
    prop.SetValue(foo, val, null);
}
return foo;

If you want to write an efficient generic class dealing with multiple types you could store each dictionary in a global dictionary>.