How to make list item value not reference to the object

Question

my list item that is already added update base on current object (obj) value. how to make list not update or how to copy obj?

    public static void ReadData<T>(string filename, T obj,string node)
    {
        var xmlDocument = new XmlDocument();
        xmlDocument.Load(filename);
        List<T> objectList = new List<T>();
        XmlNodeList xmlNodeList = xmlDocument.SelectNodes("//"+node);

        for (var i = 0; i < xmlNodeList?.Count; i++)
        {
            var j = 0;
            foreach (var objectProperty in obj.GetType().GetProperties())
            {
                if (objectProperty.CanRead)
                {
                    object value;
                    if (objectProperty.PropertyType == typeof(bool))
                    {
                        value = bool.Parse(xmlNodeList[i].ChildNodes[j].InnerText);
                    }
                    else
                    {
                       value= xmlNodeList[i].ChildNodes[j].InnerText;
                    }
                    objectProperty.SetValue(obj, value);
                    j++;
                }
            }
            objectList.Add(obj);
        }

}

If `T` is a `struct`, then it is already a copy. If `T` is a `class`, then : the only way to do this is via a shallow or deep clone. At that point, you should be searching for "how to clone an object in .NET" — Marc Gravell, Jan 26 '18 at 09:42
"how to clone non specific object?" - two people have already given you two different approaches to that; have you tried either? how did it go? — Marc Gravell, Jan 26 '18 at 10:14

Ray Krungkaew · Accepted Answer · 2018-01-26T09:53:35.133

3

1.You can implement IConeable

public class ClonableClass : ICloneable
{
   public object Clone()
   {
      return this.MemberwiseClone();
   }
}

Now a and b do not refer to the same object.

var a = new ClonableClass ();
var b = (ClonableClass)a.Clone();

2.The simplest way to deep clone is to just serialize the object then deserialize it.

var objStr= JsonConvert.SerializeObject(obj);
var newObj = JsonConvert.DeserializeObject<T>(objStr);

3.Another way will require brute force coding but you can get every last bit of performance gain. You can just create a new object then assign all properties manually.

edited Jan 26 '18 at 09:53

answered Jan 26 '18 at 09:41

Ray Krungkaew

6,652
1
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2

note that this will work, but implements a shallow clone; it is often important to know whether a clone is shallow or deep. I would also probably recommend fixing the typing, i.e. `public Foo Clone() { /* actual code */ } object ICloneable.Clone() => Clone();` – Marc Gravell Jan 26 '18 at 09:43
1

For the easy, you can just serialize the object the deserialize it. – Ray Krungkaew Jan 26 '18 at 09:53

score 1 · Answer 2 · answered Jan 26 '18 at 09:50

Serialization and deserialization an object is an option to clone objects.

public static T Clone<T>(this T source)
{
    var serialized = JsonConvert.SerializeObject(source);
    return JsonConvert.DeserializeObject<T>(serialized);
}

Then clone the desired object;

var obj = new SampleClass
{
    Id = 1,
    Name = ""
};
var clonedObj = obj.Clone();

How to make list item value not reference to the object

2 Answers2