C# XML Deserialize ignore Default value attribute-CodePudding

I am having a class with a set of properties that I use as user level settings. Each property has a Default Value attribute. Few has XmlIgnore attribute to avoid the serialization.

When serializing this class object as memory stream and it writes it correct, but while de-serializing it actually creates an object with all the properties default value which was not part of the serialized object. How can I ignore this default value initialization for few properties? Thanks in advance.

XmlSerializer serializer = new mlSerializer(typeof(DisplayPreferences));
DisplayPreferences newPrefs = null;
MemoryStream ms = new System.IO.MemoryStream(System.Text.Encoding.UTF8.GetBytes(prefs));
newPrefs = (DisplayPreferences)serializer.Deserialize(ms);
if (newPrefs != null)
{
   newPrefs.CopyTo(Editor.prefs);
}

This app is built in .NET 4.6 (winforms)

CodePudding user response：

Welcome to stackoverflow.

You've given very little information on how you are de-serializing them (a code snippet would help), but I assume you are de-serializing them into a typed object. If that is the case, then what you are experiencing is standard behavior. That is the whole point of the default value, you can't "partially de-serialize a typed object".

What you can do however is either:

de-serializing the object into a raw xmlObject, and write a custom serializer for it.

Make the properties nullable, this is typically where DTO's are useful.See below.

 public class SomeTypedObjectDTO
 {
       public Guid? NullableGuid { get; set; }
       public int? NullableInt { get; set; }
 }

----UPDATE----

I tired to keep this in line with your code. Lets say you have the following object.

public class DisplayPreferences
{
   public Guid Id { get; set; }
   public string Name { get; set; }
   public int Level { get; set; }
   public bool CanDisplay { get; set; }
}

And lets say you only want to serialize the "CanDisplay" and the "level" properties. You can create a DTO (Data Transfer object) for it, which is basically a stripped down version of the original object.

DTO:

public class DisplayPreferencesDTO
{
    public int Level { get; set; }
    public bool CanDisplay { get; set; }
}

Then I believe all you need to do is change the generic typeof() to use the DTO instead of the actual object.

XmlSerializer serializer = new mlSerializer(typeof(DisplayPreferencesDTO));

You can then map the DTO back to the original object when you like and if you like. You can either do this mapping manually or use a framework called Automapper. Automapper was explicitly designed for mapping DTO's.

If you need me to clarify anything let me know.

Happy coding!

CodePudding user response：

You may want to make them as null? just make them to nullable prop such as make a int to int?