How to convert object to Dictionary<TKey, TValue> in C#?

Question

How do I convert a dynamic object to a Dictionary<TKey, TValue> in C# What can I do?

public static void MyMethod(object obj)
{
    if (typeof(IDictionary).IsAssignableFrom(obj.GetType()))
    {
        // My object is a dictionary, casting the object:
        // (Dictionary<string, string>) obj;
        // causes error ...
    }
    else
    {
        // My object is not a dictionary
    }
}

Answer 1

The above answers are all cool. I found it easy to json serialize the object and deserialize as a dictionary.

var json = JsonConvert.SerializeObject(obj);
var dictionary = JsonConvert.DeserializeObject<Dictionary<string, string>>(json);

I don't know how performance is effected but this is much easier to read. You could also wrap it inside a function.

public static Dictionary<string, TValue> ToDictionary<TValue>(object obj)
{       
    var json = JsonConvert.SerializeObject(obj);
    var dictionary = JsonConvert.DeserializeObject<Dictionary<string, TValue>>(json);   
    return dictionary;
}

Use like so:

var obj = new { foo = 12345, boo = true };
var dictionary = ToDictionary<string>(obj);

Answer 2

I use this helper:

public static class ObjectToDictionaryHelper
{
    public static IDictionary<string, object> ToDictionary(this object source)
    {
        return source.ToDictionary<object>();
    }

    public static IDictionary<string, T> ToDictionary<T>(this object source)
    {
        if (source == null)
            ThrowExceptionWhenSourceArgumentIsNull();

        var dictionary = new Dictionary<string, T>();
        foreach (PropertyDescriptor property in TypeDescriptor.GetProperties(source))
            AddPropertyToDictionary<T>(property, source, dictionary);
        return dictionary;
    }

    private static void AddPropertyToDictionary<T>(PropertyDescriptor property, object source, Dictionary<string, T> dictionary)
    {
        object value = property.GetValue(source);
        if (IsOfType<T>(value))
            dictionary.Add(property.Name, (T)value);
    }

    private static bool IsOfType<T>(object value)
    {
        return value is T;
    }

    private static void ThrowExceptionWhenSourceArgumentIsNull()
    {
        throw new ArgumentNullException("source", "Unable to convert object to a dictionary. The source object is null.");
    }
}

the usage is just to call .ToDictionary() on an object

Hope it helps.

Answer 3

    public static KeyValuePair<object, object > Cast<K, V>(this KeyValuePair<K, V> kvp)
    {
        return new KeyValuePair<object, object>(kvp.Key, kvp.Value);
    }

    public static KeyValuePair<T, V> CastFrom<T, V>(Object obj)
    {
        return (KeyValuePair<T, V>) obj;
    }

    public static KeyValuePair<object , object > CastFrom(Object obj)
    {
        var type = obj.GetType();
        if (type.IsGenericType)
        {
            if (type == typeof (KeyValuePair<,>))
            {
                var key = type.GetProperty("Key");
                var value = type.GetProperty("Value");
                var keyObj = key.GetValue(obj, null);
                var valueObj = value.GetValue(obj, null);
                return new KeyValuePair<object, object>(keyObj, valueObj);
            }
        }
        throw new ArgumentException(" ### -> public static KeyValuePair<object , object > CastFrom(Object obj) : Error : obj argument must be KeyValuePair<,>");
    }

From the OP:

Instead of converting my whole Dictionary, i decided to keep my obj dynamic the whole time. When i access the keys and values of my Dictionary with a foreach later, i use foreach(dynamic key in obj.Keys) and convert the keys and values to strings simply.