When processing data in the .NET environment, you may need to convert the DataReader (a data flow that only reads forward) to more easy to manage formats, such as list . This conversion allows you to access and process structured data more efficiently. solution: extension

A method of conversion is to use the expansion method. The example is as follows:

Public Static Ienumerable Select (this IDAREADER Reader, Func Project) {{ While (Reader.read ()) {{ yield Return Project (Reader); } } This expansion method allows you to select data from the DataReader with a projection function and convert it to Ienumeration

public static IEnumerable Select(this IDataReader reader,
                                       Func projection)
{
    while (reader.Read())
    {
        yield return projection(reader);
    }
}

using (IDAREADER Reader = ...) {{ List CUSTOMERS = Reader.select (R => New Customer { Customerid = r ["id"] is dbnull? Null: r ["id"]. Tostring (), Cusomername = r ["name"] is dbnull? Null: r ["name"]. Tostring () }). Tolist (); }

This example converts the row in the DataReader into a list of the Customer object. alternative method: Special method for physical types

Or, you can create a dedicated static method in the Customer entity:

using (IDataReader reader = ...)
{
    List customers = reader.Select(r => new Customer {
        CustomerId = r["id"] is DBNull ? null : r["id"].ToString(),
        CustomerName = r["name"] is DBNull ? null : r["name"].ToString()
    }).ToList();
}

Using this method, you can simplify the conversion process:

using (IDAREADER Reader = ...) {{ List CUSTOMERS = Reader.Select With these technologies, you can efficiently convert data in dataReader into list