C# cast Dictionary to Dictionary (Involving Reflection)

Question

Is it possible to cast a Dictionary to a consistent intermediate generic type? So I would be able to cast <

Answer 1

When I stumbled onto the same situation, I created the following helper:

/// 

/// Casts a dictionary object to the desired Dictionary type.
/// 
/// The target Key type.
/// The target value type.
/// The dictionary to cast.
/// A copy of the input dictionary, casted to the provided types.
private Dictionary CastDictionary(IDictionary dictionary)
{
    // Get the dictionary's type.
    var dictionaryType = typeof(Dictionary);

    // If the input is not a dictionary.
    if (dictionaryType.IsAssignableFrom(typeof(Dictionary<,>)))
    {
        // Throw an exception.
        throw new Exception("The cast to a dictionary failed: The input object is not a dictionary.");
    }

    // Get the generic arguments of the dictionary.
    var arguments = dictionaryType.GetGenericArguments();

    // If the first type of the dictionary is not a descendant of TKey.
    if (!(arguments[0] is TKey || arguments[0].IsAssignableFrom(typeof(TKey)))
        // Or its second type is not a descendant of TValue.
        || !(arguments[1] is TValue || arguments[1].IsAssignableFrom(typeof(TValue))))
    {
        // Throw an exception.
        throw new Exception("The cast to a dictionary failed: The input dictionary's signature does not match <" + typeof(TKey).Name + ", " + typeof(TValue).Name + ">");
    }

    // Get the dictionary's default constructor.
    var constructor = dictionaryType.GetConstructor(Type.EmptyTypes);

    // Create a new dictionary.
    var output = (Dictionary)constructor.Invoke(null);

    // Loop through the dictionary's entries.
    foreach (DictionaryEntry entry in dictionary)
    {
        // Insert the entries.
        output.Add((TKey)entry.Key, (TValue)entry.Value);
    }

    // Return the result.
    return output;
}

Could be used in your case as follows:

FieldInfo field = (IDictionary)this.GetType().GetField(fieldName);

Dictionary dict = CastDictionary(field.GetValue(this));