//public static Dictionary<TKey, TVal> ToDictionary<TKey, TVal>(this IEnumerable<TVal> colxn, Func<TVal, TKey> keySelector)
//{
// var dict = new Dictionary<TKey, TVal>();
// foreach (var item in colxn)
// dict.Add(keySelector(item), item);
// return dict;
//}
public static T SingleOrDefault <T>(this IEnumerable <T> items,
Func <T, bool> predicate, string key, object value, string operatr = "==")
{
var matches = items?.Where(predicate);
if (matches == null)
{
return(default(T));
}
if (matches.Count() == 0)
{
return(default(T));
}
if (matches.Count() == 1)
{
return(matches.First());
}
throw Fault.MultiMatch <T>(key, value, operatr);
}
