Refine RealmContext implementation API

osu.Game/Database/RealmObjectExtensions.cs

@@ -0,0 +1,51 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using AutoMapper;
+using osu.Game.Input.Bindings;
+using Realms;
+
+namespace osu.Game.Database
+{
+    public static class RealmObjectExtensions
+    {
+        private static readonly IMapper mapper = new MapperConfiguration(c =>
+        {
+            c.ShouldMapField = fi => false;
+            c.ShouldMapProperty = pi => pi.SetMethod != null && pi.SetMethod.IsPublic;
+
+            c.CreateMap<RealmKeyBinding, RealmKeyBinding>();
+        }).CreateMapper();
+
+        /// <summary>
+        /// Create a detached copy of the each item in the collection.
+        /// </summary>
+        /// <param name="items">A list of managed <see cref="RealmObject"/>s to detach.</param>
+        /// <typeparam name="T">The type of object.</typeparam>
+        /// <returns>A list containing non-managed copies of provided items.</returns>
+        public static List<T> Detach<T>(this IEnumerable<T> items) where T : RealmObject
+        {
+            var list = new List<T>();
+
+            foreach (var obj in items)
+                list.Add(obj.Detach());
+
+            return list;
+        }
+
+        /// <summary>
+        /// Create a detached copy of the item.
+        /// </summary>
+        /// <param name="item">The managed <see cref="RealmObject"/> to detach.</param>
+        /// <typeparam name="T">The type of object.</typeparam>
+        /// <returns>A non-managed copy of provided item. Will return the provided item if already detached.</returns>
+        public static T Detach<T>(this T item) where T : RealmObject
+        {
+            if (!item.IsManaged)
+                return item;
+
+            return mapper.Map<T>(item);
+        }
+    }
+}