Generic mappers (to use in extention methode)

WF_EF_Api/Shared/Mapper.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Shared
+{
+    public class Mapper<T,U> where T : class
+                             where U : class
+    {
+        readonly HashSet<Tuple<T, U>> mapper = new HashSet<Tuple<T, U>>();
+
+        public bool AddMapping(T t, U u)
+        {
+            var mapping = new Tuple<T, U>(t, u);
+            if (mapper.Contains(mapping)) return false;
+            mapper.Add(mapping);
+            return true;
+        }
+
+        public T? GetT(U u)
+        {
+            var result = mapper.Where(tuple => ReferenceEquals(tuple.Item2, u));
+            if (result.Count() != 1)
+            {
+                return null;
+            }
+            return result.First().Item1;
+        }
+
+        public U? GetU(T t)
+        {
+            var result = mapper.Where(tuple => ReferenceEquals(tuple.Item1, t));
+            if (result.Count() != 1)
+            {
+                return null;
+            }
+            return result.First().Item2;
+        }
+
+        public void Reset()
+        {
+            mapper.Clear();
+        }
+    }
+}