datacontract

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.Serialization;
using System.Xml;


namespace ConsoleApp1
{
    // requirements for class which will be saved:
     //    - class must be marked as [DataContract]
     //    - all variables, which shall be saved, must be marked as [DataMember]

    [DataContract]
    public class Car
    {
        [DataMember]
        public string name;

        [DataMember]
        double power;

        [DataMember]
        List<Wheel> wheels;

        public Car(string name, double power, List<string> directions)
        {
            this.name = name;
            this.power = power;
            wheels = directions.Select(d => new Wheel(d)).ToList();
        }

        public override string ToString()
        {
            string returnString = name + " has " + power + "kW and those wheels: ";
            foreach (var wheel in wheels)
                returnString += wheel.direction + " ";
            return returnString;
        }
    }

    // requirements for subclasses of saved class:
    //    - must have a public parameterless constructor

    public class Wheel
    {
        public string direction;

        public Wheel() { }

        public Wheel(string direction)
        {
            this.direction = direction;
        }
    }

    class Program
    {
        static void SaveViaDataContractSerialization<T>(T serializableObject, string filepath)
        {
            var serializer = new DataContractSerializer(typeof(T));
            var settings = new XmlWriterSettings()
            {
                Indent = true,
                IndentChars = "\t",
            };
            var writer = XmlWriter.Create(filepath, settings);
            serializer.WriteObject(writer, serializableObject);
            writer.Close();
        }


        static T LoadViaDataContractSerialization<T>(string filepath)
        {
            var fileStream = new FileStream(filepath, FileMode.Open);
            var reader = XmlDictionaryReader.CreateTextReader(fileStream, new XmlDictionaryReaderQuotas());
            var serializer = new DataContractSerializer(typeof(T));
            T serializableObject = (T)serializer.ReadObject(reader, true);
            reader.Close();
            fileStream.Close();
            return serializableObject;
        }


        static void Main(string[] args)
        {
            // Save single object
            Car bmw = new Car("BMW", 200, new List<string> { "Left", "Right" });    // create object
            SaveViaDataContractSerialization(bmw, "bmw.xml");                       // save object
            bmw = null;                                                             // delete object
            bmw = LoadViaDataContractSerialization<Car>("bmw.xml");                 // reload object
            Console.WriteLine(bmw.ToString());                                      // print object



            // Save list of objects
            List<Car> carList = new List<Car>                                       // create object list
            {
                new Car("Porsche", 250, new List<string> { "Left" }),
                new Car("Mercedes", 150, new List<string> { "Front", "Back" }),
                new Car("Aston Martin", 300, new List<string> { "Front" })
            };
            SaveViaDataContractSerialization(carList, "cars.xml");                  // save object list
            carList = null;                                                         // delete object list
            carList = LoadViaDataContractSerialization<List<Car>>("cars.xml");      // reload object list
            foreach (var a in carList)                                              // print object list
                Console.WriteLine(a.ToString());

            Console.ReadLine();
        }
    }
}