Is there any way to update the Key element of a Dictionary directly in .NET?

Question

At the moment, I have no other way than this one (an indirect update):

private void UpdateKey(Dictionary<string,object> dict, string oldKey, string newKey){
    if(dict.ContainsKey(oldKey)){
          object value = dict[oldKey];
          dict.Remove(oldKey);
          dict.Add(newKey,value);
    }
}

Do you have another better way?

Of course the above method is just a simple one, to make it work well without throwing any exception, we have to check the newKey for duplication with already keys in the Dictionary. Like this:

private void UpdateKey(Dictionary<string,object> dict, string oldKey, string newKey){
    if(dict.ContainsKey(oldKey)){
          object value = dict[oldKey];
          dict.Remove(oldKey);              
          dict[newKey] = value;
    }
}

Thank you very much in advance!

Answer 1

I would use TryGetValue method instead of Contains:

private void UpdateKey(Dictionary<string,object> dict, string oldKey, string newKey){
    object value;
    if(dict.TryGetValue(oldKey, out value)){
          dict.Remove(oldKey);
          dict.Add(newKey, value);
    }
}

But you still need to get value first, add it with another key and remove the old one. You can't do it any other way.

By the way: you can make the method generic to operate on more then just one dictionary type:

private static void UpdateKey<TKye, TValue>(Dictionary<TKey, TValue> dict, TKey oldKey, TKey newKey){
    TValue value;
    if(dict.TryGetValue(oldKey, out value)){
          dict.Remove(oldKey);
          dict.Add(newKey, value);
    }
}

Or you can event write your own Extension method on IDictionary<TKey, TValue>:

public static class DictionaryExtensions
{
    public static void UpdateKey<TKye, TValue>(this IDictionary<TKey, TValue> dict, TKey oldKey, TKey newKey){
        TValue value;
        if(dict.TryGetValue(oldKey, out value)){
              dict.Remove(oldKey);
              dict.Add(newKey, value);
        }
    }
}

and then call it like standard Dictionary method:

myDict.UpdateKey(oldKey, newKey);