Why JavaScriptSerializer de-serializes a property to it's default value or null

Question

I am using JavaScriptSerializer to serialize and deserialize the properties in my object. Everything works fine during serialization. However, few properties are serialized to default values instead of the actual value assigned to them.

This is my class

[Serializable]
public Class SimpleClass
{
    //This property is serialized properly
    //But always de-serialized to null
    [DefaultValue("null")]
    public List<string> Collection { get; }    
}

This is the code used for serialization and de-serialization

    SimpleClass testObject =new SimpleClass();
    testObject.Collection.Add("One");
    testObject.Collection.Add("Two");
    testObject.Collection.Add("Three");
    testObject.Collection.Add("Four");
    testObject.Collection.Add("Five");

    //Serializing the above object
    string serializedString = new JavaScriptSerializer().Serialize(testObject);

    //Deserializing the serialized string
    testObject = new JavaScriptSerializer().Deserialize<SimpleClass>(serializedString);

However, after de-serialization, the value of testObject.Collection property is always null

Answer 1

Any property without setter is always de-serialized to default value.

JavaScriptSerializer internally uses Reflection to serialize and deserialize an object. If setter is not present in a property, then the serializer cannot modify the value of this property. So, it will be initialized with its default value.

In the above code, property Collection does not have a default value so it is assigned null during de-serialization.