Fix cache.Group MissingKeyException Fixes #527 (#666)

reactivemarbles · Nov 25, 2022 · 9f7638f · 9f7638f
1 parent b44fdee
commit 9f7638f
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Showing 2 changed files with 42 additions and 13 deletions.
diff --git a/src/DynamicData.Tests/Cache/GroupFixture.cs b/src/DynamicData.Tests/Cache/GroupFixture.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Linq;
 using System.Reactive.Linq;
@@ -22,6 +23,42 @@ public GroupFixture()
         _source = new SourceCache<Person, string>(p => p.Name);
     }
 
+    [Fact]
+    public void Kaboom()
+    {
+        SourceCache<Mytype, int> cache = new(x => x.Key);
+        List<Mytype> listWithDuplicates = new()
+        {
+            new(1, "G1"),
+            new(1, "G2"),
+        };
+        cache
+            .Connect()
+            .Group(x => x.Grouping)
+            .Subscribe();
+
+        cache.Edit(x =>
+        {
+            x.AddOrUpdate(listWithDuplicates);
+            x.Clear();
+            x.AddOrUpdate(listWithDuplicates);
+        });
+    }
+
+    class Mytype
+    {
+        public Mytype(int key, string grouping)
+        {
+            Key = key;
+            Grouping = grouping;
+        }
+
+        public int Key { get; set; }
+        public string Grouping { get; set; }
+
+        public override string ToString() => $"{Key}, {Grouping}";
+    }
+
     [Fact]
     public void Add()
     {

diff --git a/src/DynamicData/Cache/Internal/GroupOn.cs b/src/DynamicData/Cache/Internal/GroupOn.cs
@@ -101,8 +101,7 @@ public Grouper(Func<TObject, TGroupKey> groupSelectorKey)
 
             // 1. iterate and maintain child caches (_groupCache)
             // 2. maintain which group each item belongs to (_itemCache)
-            grouped.ForEach(
-                group =>
+            grouped.ForEach(group =>
                 {
                     var groupItem = GetCache(group.Key);
                     var groupCache = groupItem.group;
@@ -119,22 +118,16 @@ public Grouper(Func<TObject, TGroupKey> groupSelectorKey)
                                 switch (current.Reason)
                                 {
                                     case ChangeReason.Add:
-                                        {
-                                            groupUpdater.AddOrUpdate(current.Item, current.Key);
-                                            _itemCache[current.Key] = current;
-                                            break;
-                                        }
-
                                     case ChangeReason.Update:
                                         {
                                             groupUpdater.AddOrUpdate(current.Item, current.Key);
 
                                             // check whether the previous item was in a different group. If so remove from old group
-                                            var previous = _itemCache.Lookup(current.Key).ValueOrThrow(() => new MissingKeyException($"{current.Key} is missing from previous value on update. Object type {typeof(TObject).FullName}, Key type {typeof(TKey).FullName}, Group key type {typeof(TGroupKey).FullName}"));
+                                            var previous = _itemCache.Lookup(current.Key);
 
-                                            if (!EqualityComparer<TGroupKey>.Default.Equals(previous.GroupKey, current.GroupKey))
+                                            if (previous.HasValue && !EqualityComparer<TGroupKey>.Default.Equals(previous.Value.GroupKey, current.GroupKey))
                                             {
-                                                _groupCache.Lookup(previous.GroupKey).IfHasValue(
+                                                _groupCache.Lookup(previous.Value.GroupKey).IfHasValue(
                                                     g =>
                                                     {
                                                         g.Update(u => u.Remove(current.Key));
@@ -146,10 +139,9 @@ public Grouper(Func<TObject, TGroupKey> groupSelectorKey)
                                                         _groupCache.Remove(g.Key);
                                                         result.Add(new Change<IGroup<TObject, TKey, TGroupKey>, TGroupKey>(ChangeReason.Remove, g.Key, g));
                                                     });
-
-                                                _itemCache[current.Key] = current;
                                             }
 
+                                            _itemCache[current.Key] = current;
                                             break;
                                         }