Serializing Dictionary<string, object> when dictionary was initialized with case insensitive string comparer

Question

I am serializing a Dictionary to XML. When I create a new dictionary I use the constructor to provide EqualityComparer without casing for instance

var tabs = new Dictionary<string,Tab>(StringComparer.OrdinalIgnoreCase);

I then serialize to XML and when I deserialize information about casing is lost - the deserialization is made to the Dictionary with GenericEqualityComparer, which apparently is case sensitive, because it doesn't find my keys if they are not cased correctly.

Any ideas how can I change it?

One way would be to create a new dictionary and copy the data from the deserialized over to the new one but this seems troublesome.

UPDATE:

The deserialization worked the whole time it is just that it deserializes the serialized Dictionary to one that does not use case insensitive keys.

Answer 1

I know this question is quite old, but I recently found myself searching for how to do this.

Using .Net4 (like @mare said), you can create some really nice extension methods to make this a breeze. Check out https://stackoverflow.com/a/5941122/435460 for a nice and simple implementation.

After a lot of digging, this worked like a charm for me.

Answer 2

Edit:

Per the comments, it appears this approach may be outdated in .NET 4.

End Edit

Dictionaries happen to require a little help to serialize and deserialize.

Here is a good example of an XML Serializable dictionary:

http://weblogs.asp.net/pwelter34/archive/2006/05/03/444961.aspx

You can make it case insensitive by changing the class declaration and adding a constructor, and tweaking a line.

** EDIT: Corrected syntax error below. /EDIT**

public class SerializableDictionary<TValue>
    : Dictionary<string, TValue>, IXmlSerializable
{
    public SerializableDictionary()
        : base(StringComparer.InvariantCultureIgnoreCase)
    {
    }

    // ...
}

Change the line this.Add(key, value); to this[key] = value;.

At any rate, you may need to massage some of the details, but this should get you well on the road.

Answer 3

You just have to wrap up your new dictionary in the Constructor:

Dictionary<string, Tab> tabs ;
tabs = new Dictionary<string, Tab>((Dictionary<string, Tab>)serializer.ReadObject(reader),StringComparer.OrdinalIgnoreCase);

Answer 4

An old question I realize, but was just digging through the source to Dictionary and noticed that it should in fact serialize the Comparer:

info.AddValue(ComparerName, comparer, typeof(IEqualityComparer<tkey>));

Then in the implementation of IDeserializationCallback.OnDeserialization it retrieves the Comparar:

comparer = (IEqualityComparer<tkey>)m_siInfo.GetValue(ComparerName, typeof(IEqualityComparer<tkey>));

Classes implementing the interface IDeserializationCallback specify a method that should be executed after the an instance has been deserialized, but before its returned to your code.

Ref: Dictionary.cs GetObjectData and OnDeserialization methods