Umbraco-CMS/src/Umbraco.Core/NameValueCollectionExtensions.cs

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Linq;
using System.Text;

namespace Umbraco.Core
{
    internal static class NameValueCollectionExtensions
    {
        public static IEnumerable<KeyValuePair<string, string>> AsEnumerable(this NameValueCollection nvc)
        {
            foreach (string key in nvc.AllKeys)
            {
                yield return new KeyValuePair<string, string>(key, nvc[key]);
            }
        }

        public static bool ContainsKey(this NameValueCollection collection, string key)
        {
            return collection.Keys.Cast<object>().Any(k => (string) k == key);
        }

        public static T GetValue<T>(this NameValueCollection collection, string key, T defaultIfNotFound)
        {
            if (collection.ContainsKey(key) == false)
            {
                return defaultIfNotFound;
            }

            var val = collection[key];
            if (val == null)
            {
                return defaultIfNotFound;
            }

            var result = val.TryConvertTo<T>();

            return result.Success ? result.Result : defaultIfNotFound;
        }
    }
}