Dynamic Object Serialization

Question

I tried to serialize a DynamicObject class with BinaryFormatter, but:

• Output file is too big, not exactly wire-friendly
• Circular References not handled (stuck while serializing)

Since serializing a DynamicObject means very little by itself, here's the class I tried to serialize:

[Serializable()]
class Entity
    : DynamicObject, ISerializable
{

    IDictionary<string, object> values = new Dictionary<string, object>();

    public Entity()
    {

    }

    protected Entity(SerializationInfo info, StreamingContext ctx)
    {
        string fieldName = string.Empty;
        object fieldValue = null;

        foreach (var field in info)
        {
            fieldName = field.Name;
            fieldValue = field.Value;

            if (string.IsNullOrWhiteSpace(fieldName))
                continue;

            if (fieldValue == null)
                continue;

            this.values.Add(fieldName, fieldValue);
        }

    }

    public override bool TryGetMember(GetMemberBinder binder, out object result)
    {
        this.values.TryGetValue(binder.Name, out result);

        return true;
    }

    public override bool TrySetMember(SetMemberBinder binder, object value)
    {
        this.values[binder.Name] = value;

        return true;
    }        

    void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
    {            
        foreach (var kvp in this.values)
        {
            info.AddValue(kvp.Key, kvp.Value);                 
        }
    }

}

(I guess I could have used an ExpandoObject, but that's another story.)

Here's a simple test program:

    static void Main(string[] args)
    {
        BinaryFormatter binFmt = new BinaryFormatter();

        dynamic obj = new Entity();
        dynamic subObj = new Entity();
        dynamic obj2 = null;

        obj.Value = 100;
        obj.Dictionary = new Dictionary<string, int>() { { "la la la", 1000 } };

        subObj.Value = 200;
        subObj.Name = "SubObject";

        obj.Child = subObj;

        using (var stream = new FileStream("test.txt", FileMode.OpenOrCreate))
        {
            binFmt.Serialize(stream, obj);                
        }

        using (var stream = new FileStream("test.txt", FileMode.Open))
        {
            try
            {
                obj2 = binFmt.Deserialize(stream);                    
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex);
            }                
        }

        Console.ReadLine();

    }

Putting some breakpoints here and there helped me have a look at obj2 contents and it looks like the original data is correctly deserialized, though with the above shortcomings if you get imaginative and move data around.

I had a look at Marc Gravell's protobuf-net, but I'm not really sure how to use it in such a context (I'm not even sure I picked up the right version from the repository, but hey).

I know it's more code than words, but I don't think I can explain the scenario any better. Please do tell if there's something I can add to make this question clearer.

Any help is much appreciated.

Answer 1

I'm 98% certain that this sequence will work for a dynamic object.

1. convert object to an Expando Object
2. cast expando object to be of type Dictionary
3. use ProtoBuf-net Serializer.Serialize / .Deserialize as per normal
4. convert dictionary to Expando Object

You can convert objects to a collection of name/value pairs for transfering.

That's just a small subset of what dynamic can do, but perhaps it is enough for you.

There's some custom code to handle some of the conversions above that I can show you if there's interest.

I don't have a solution for when dynamic is a placeholder to a class. For this case I'd suggest getting the type and using a switch statement to serialize / deserialize as you require. For this last case, you'd need to place a something to indicate which type of generic deserialization that you need (string / id / fully qualified type name / etc). Assumption is that you are dealing with a list of expected types.

Note: Expando implements IDictionary. An Expando is merely merely a list of key/value pairs. ie. the thing you dot into is the key, and the value is the return from whatever chain of functions implements that. There are a set of dynamic interfaces for customising the syntactic sugar experience, but most of the time you wont to look at them.

refs:

• Dictionary from IDictionary using the constructor -- http://msdn.microsoft.com/en-us/library/et0ke8sz(v=vs.110).aspx
• IDictionary/Dictionary to Expando -- http://theburningmonk.com/2011/05/idictionarystring-object-to-expandoobject-extension-method/