C# cast Dictionary<string, AnyType> to Dictionary<string, Object> (Involving Reflection)

Following AakashM's answer, the Cast doesn't seem to play ball. You can get around it by using a little helper method though:

IDictionary dictionary = (IDictionary)field.GetValue(this);
Dictionary<string, object> newDictionary = CastDict(dictionary)
                                           .ToDictionary(entry => (string)entry.Key,
                                                         entry => entry.Value);

private IEnumerable<DictionaryEntry> CastDict(IDictionary dictionary)
{
    foreach (DictionaryEntry entry in dictionary)
    {
        yield return entry;
    }
}

The duck typing in foreach is handy in this instance.

Is this helping you ?

Dictionary<a, b> output =
   input.ToDictionary(item => item.Key, item => (SomeType)item.Value);

Even if you could find some way to express this, it would be the wrong thing to do - it's not true that a Dictionary<string, bool> is a Dictionary<string, object>, so we definitely don't want to cast. Consider that if we could cast, we could try and put a string in as a value, which obviously doesn't fit!

What we can do, however, is cast to the non-generic IDictionary (which all Dictionary<,>s implement), then use that to construct a new Dictionary<string, object> with the same values:

FieldInfo field = this.GetType().GetField(fieldName);
IDictionary dictionary = (IDictionary)field.GetValue(this);
Dictionary<string, object> newDictionary = 
    dictionary
    .Cast<dynamic>()
    .ToDictionary(entry => (string)entry.Key,
                  entry => entry.Value);

(note that you can't use .Cast<DictionaryEntry> here for the reasons discussed here. If you're pre-C# 4, and so don't have dynamic, you'll have to do the enumeration manually, as Gibsnag's answer does)