Implement IList on DataGridCollectionView. (#13313)

Fixes #11586

src/Avalonia.Controls.DataGrid/Collections/DataGridCollectionView.cs

@@ -54,7 +54,7 @@ namespace Avalonia.Collections
     /// <summary>
     /// DataGrid-readable view over an IEnumerable.
     /// </summary>
-    public sealed class DataGridCollectionView : IDataGridCollectionView, IDataGridEditableCollectionView, INotifyPropertyChanged 
+    public sealed class DataGridCollectionView : IDataGridCollectionView, IDataGridEditableCollectionView, IList, INotifyPropertyChanged 
     {
         /// <summary>
         /// Since there's nothing in the un-cancelable event args that is mutable,
@@ -1153,6 +1153,17 @@ namespace Avalonia.Collections
             get { return GetItemAt(index); }
         }
 
+        bool IList.IsFixedSize => false;
+        bool IList.IsReadOnly => true;
+        bool ICollection.IsSynchronized => false;
+        object ICollection.SyncRoot => this;
+
+        object IList.this[int index]
+        {
+            get => this[index];
+            set => throw new NotSupportedException();
+        }
+
         /// <summary>
         /// Add a new item to the underlying collection.  Returns the new item.
         /// After calling AddNew and changing the new item as desired, either
@@ -3981,6 +3992,11 @@ namespace Avalonia.Collections
             }
         }
 
+        int IList.Add(object value) => throw new NotSupportedException();
+        void IList.Clear() => throw new NotSupportedException();
+        void IList.Insert(int index, object value) => throw new NotSupportedException();
+        void ICollection.CopyTo(Array array, int index) => InternalList.CopyTo(array, index);
+
         /// <summary>
         /// Creates a comparer class that takes in a CultureInfo as a parameter,
         /// which it will use when comparing strings.

src/Avalonia.Controls.DataGrid/DataGridDataConnection.cs

@@ -193,18 +193,17 @@ namespace Avalonia.Controls
             }
         }
 
-        /// <summary>Try get number of DataSource itmes.</summary>
+        /// <summary>Try get number of DataSource items.</summary>
         /// <param name="allowSlow">When "allowSlow" is false, method will not use Linq.Count() method and will return 0 or 1 instead.</param>
         /// <param name="getAny">If "getAny" is true, method can use Linq.Any() method to speedup.</param>
-        /// <param name="count">number of DataSource itmes.</param>
-        /// <returns>true if able to retrieve number of DataSource itmes; otherwise, false.</returns>
+        /// <param name="count">number of DataSource items.</param>
+        /// <returns>true if able to retrieve number of DataSource items; otherwise, false.</returns>
         internal bool TryGetCount(bool allowSlow, bool getAny, out int count)
         {
             bool result;
             (result, count) = DataSource switch
             {
                 ICollection collection => (true, collection.Count),
-                DataGridCollectionView cv => (true, cv.Count),
                 IEnumerable enumerable when allowSlow && !getAny => (true, enumerable.Cast<object>().Count()),
                 IEnumerable enumerable when getAny => (true, enumerable.Cast<object>().Any() ? 1 : 0),
                 _ => (false, 0)