How to handle a generic dictionary whose types are unknown and don't matter?

Question

If 'value' is an incoming generic dictionary whose types are unknown/don't matter, how do I take its entries and put them into a target dictionary of type IDictionary<object, object> ?

if(type == typeof(IDictionary<,>))
{
    // this doesn't compile 
    // value is passed into the method as object and must be cast       
    IDictionary<,> sourceDictionary = (IDictionary<,>)value;

    IDictionary<object,object> targetDictionary = new Dictionary<object,object>();

    // this doesn't compile
    foreach (KeyValuePair<,> sourcePair in sourceDictionary)
    {
         targetDictionary.Insert(sourcePair.Key, sourcePair.Value);
    }

    return targetDictionary; 
}

EDIT:

Thanks for the responses so far.

The problem here is that the argument to Copy is only known as type 'object'. For example:

public void CopyCaller(object obj) 
{ 
    if(obj.GetType() == typeof(IDictionary<,>) 
         Copy(dictObj); // this doesn't compile 
} 

Answer 1

This may be a fix for you but you'll need .net 3.5 or greater to use the var keyword.

// this should compile
foreach (var sourcePair in sourceDictionary)
{
     targetDictionary.Insert(sourcePair.Key, sourcePair.Value);
}

Answer 2

Make your method generic as well and then you'll be able to do what you're doing. You won't have to change your usage pattern since the compiler will be able to infer generic types from input types.

public IDictionary<object, object> Copy(IDictionary<TKey, TValue> source)
{

    IDictionary<object,object> targetDictionary = new Dictionary<object,object>();

    foreach (KeyValuePair<TKey, TValue> sourcePair in sourceDictionary)
    {
         targetDictionary.Insert(sourcePair.Key, sourcePair.Value);
    }

    return targetDictionary; 
}

If you don't really need to convert it from IDictionary<TKey, TValue> to IDictionary<object, object> then you can use the copy constuctor of Dictionary<TKey, TValue> which accepts another dictionary as input and copies all values--just like you're doing now.

Answer 3

Here is a method (don't leave it as static, unless you need it to be, I wrote it in a quick console app) that basically converts a Dictionary of any type to an object/object dictionary.

    private static Dictionary<object,object> DeTypeDictionary<T,U>(Dictionary<T,U> inputDictionary)
    {
        Dictionary<object, object> returnDictionary = new Dictionary<object, object>();
        foreach(T key in inputDictionary.Keys)
        {
            if( (key is object) && (inputDictionary[key] is object))
            {
                returnDictionary.Add(key, inputDictionary[key]);
            }
            else
            {
                //sorry these aren't objects. they may be dynamics.
                continue;
            }

        }
        return returnDictionary;
    }

...and here is how you use it...

        Dictionary<string, DateTime> d = new Dictionary<string, DateTime>();
        d.Add("rsgfdg", DateTime.Now);
        d.Add("gfdsgd", DateTime.Now);

        Dictionary<object, object> newDictionary = DeTypeDictionary<string, DateTime>(d);