Question

I want to deserialize serialized XML containing collection of CDATA.

XML looks like this:

<User Index="1">
   <Address><![CDATA[My street 1, 1234, My city]]></Address>
   <Address><![CDATA[My next street 1, 5678, My another city]]></Address>
</User>

Since I want to add new address directly as string like this:

var user = new User();
user.Addresses.Add("My street 1, 1234, My city");
user.Addresses.Add("My next street 1, 5678, My another city");

my user class looks like that:

[XmlRoot("User", IsNullable = true)]
public class User
{
    [XmlIgnore]
    private XmlDocument xmlDoc;

    [XmlIgnore]
    private Collection<string> addresses;

    [XmlIgnore]
    private Collection<XmlNode> addressesNode;

    public User()
    {
        xmlDoc = new XmlDocument();
        addresses = new Collection<string>();
    }

    [XmlAttribute("Index")]
    public int Index { get; set; }

    [XmlElement("Address", IsNullable = true)]
    public Collection<XmlNode> AddressesNode
    {
        get
        {
            // This will create CDATA in address node. String values for
            // CDATA are in addresses collection.
            // This is causing problem.
            return new Collection<XmlNode>(addresses.Select(a => xmlDoc.CreateCDataSection(a)).ToArray());
        }
        set
        {
            // Set also address collection of string to the same values.
            addresses = new Collection<string>(value.Select(a => a.Value).ToArray());

            addressesNode = value;
        }
    }

    [XmlIgnore]
    public Collection<string> Addresses
    {
        get
        {
            return addresses;
        }
    }
}

Serializing this works fine. But while deserializing, exception is thrown

 "Collection is read-only."

Answer 1

When you create a new Collection passing the IList as a parameter, it creates the collection as a wrapper around the original list. It does NOT copy it to a new list (see here). In your addressNode setter, you create a new collection as a wrapper around your collection. You may change this to a new List instead, since the List constructor does create a new list rather than wrapping the original one (see here).