DataGrid.Items -> ItemsSource.

samples/ControlCatalog/Pages/DataGridPage.xaml

@@ -94,7 +94,7 @@
         <Grid RowDefinitions="*,Auto">
           <!-- Example of columns inheriting the data type from the Items source -->
           <DataGrid Name="dataGridEdit" Margin="12" Grid.Row="0"
-                    Items="{Binding DataGrid3Source}">
+                    ItemsSource="{Binding DataGrid3Source}">
             <DataGrid.Columns>
               <DataGridTextColumn Header="First Name" Binding="{Binding FirstName}" Width="2*" FontSize="{Binding #FontSizeSlider.Value, Mode=OneWay}" />
               <DataGridTextColumn Header="Last" Binding="{Binding LastName}" Width="2*" FontSize="{Binding #FontSizeSlider.Value, Mode=OneWay}" />

samples/ControlCatalog/Pages/DataGridPage.xaml.cs

@@ -36,7 +36,7 @@ namespace ControlCatalog.Pages
                     collectionView1.SortDescriptions.Add(dataGridSortDescription);
                 }
             };
-            dg1.Items = collectionView1;
+            dg1.ItemsSource = collectionView1;
 
             var dg2 = this.Get<DataGrid>("dataGridGrouping");
             dg2.IsReadOnly = true;
@@ -44,7 +44,7 @@ namespace ControlCatalog.Pages
             var collectionView2 = new DataGridCollectionView(Countries.All);
             collectionView2.GroupDescriptions.Add(new DataGridPathGroupDescription("Region"));
 
-            dg2.Items = collectionView2;
+            dg2.ItemsSource = collectionView2;
 
             var dg3 = this.Get<DataGrid>("dataGridEdit");
             dg3.IsReadOnly = false;

src/Avalonia.Controls.DataGrid/DataGrid.cs

@@ -152,8 +152,6 @@ namespace Avalonia.Controls
         private double _verticalOffset;
         private byte _verticalScrollChangesIgnored;
 
-        private IEnumerable _items;
-
         public event EventHandler<ScrollEventArgs> HorizontalScroll;
         public event EventHandler<ScrollEventArgs> VerticalScroll;
 
@@ -652,21 +650,18 @@ namespace Avalonia.Controls
         }
 
         /// <summary>
-        /// Identifies the ItemsSource dependency property.
+        /// Identifies the ItemsSource property.
         /// </summary>
-        public static readonly DirectProperty<DataGrid, IEnumerable> ItemsProperty =
-            AvaloniaProperty.RegisterDirect<DataGrid, IEnumerable>(
-                nameof(Items),
-                o => o.Items,
-                (o, v) => o.Items = v);
+        public static readonly StyledProperty<IEnumerable> ItemsSourceProperty =
+            AvaloniaProperty.Register<DataGrid, IEnumerable>(nameof(ItemsSource));
 
         /// <summary>
         /// Gets or sets a collection that is used to generate the content of the control.
         /// </summary>
-        public IEnumerable Items
+        public IEnumerable ItemsSource
         {
-            get { return _items; }
-            set { SetAndRaise(ItemsProperty, ref _items, value); }
+            get => GetValue(ItemsSourceProperty);
+            set => SetValue(ItemsSourceProperty, value);
         }
 
         public static readonly StyledProperty<bool> AreRowDetailsFrozenProperty =
@@ -713,7 +708,7 @@ namespace Avalonia.Controls
                 HorizontalScrollBarVisibilityProperty,
                 VerticalScrollBarVisibilityProperty);
 
-            ItemsProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnItemsPropertyChanged(e));
+            ItemsSourceProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnItemsSourcePropertyChanged(e));
             CanUserResizeColumnsProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnCanUserResizeColumnsChanged(e));
             ColumnWidthProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnColumnWidthChanged(e));
             FrozenColumnCountProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnFrozenColumnCountChanged(e));
@@ -816,10 +811,10 @@ namespace Avalonia.Controls
         }
 
         /// <summary>
-        /// ItemsProperty property changed handler.
+        /// ItemsSourceProperty property changed handler.
         /// </summary>
         /// <param name="e">The event arguments.</param>
-        private void OnItemsPropertyChanged(AvaloniaPropertyChangedEventArgs e)
+        private void OnItemsSourcePropertyChanged(AvaloniaPropertyChangedEventArgs e)
         {
             if (!_areHandlersSuspended)
             {
@@ -830,7 +825,7 @@ namespace Avalonia.Controls
 
                 if (LoadingOrUnloadingRow)
                 {
-                    SetValueNoCallback(ItemsProperty, oldValue);
+                    SetValueNoCallback(ItemsSourceProperty, oldValue);
                     throw DataGridError.DataGrid.CannotChangeItemsWhenLoadingRows();
                 }
 
@@ -1855,7 +1850,7 @@ namespace Avalonia.Controls
         {
             get
             {
-                if (CurrentSlot == -1 || Items == null || RowGroupHeadersTable.Contains(CurrentSlot))
+                if (CurrentSlot == -1 || ItemsSource == null || RowGroupHeadersTable.Contains(CurrentSlot))
                 {
                     return null;
                 }

src/Avalonia.Controls.DataGrid/DataGridBoundColumn.cs

@@ -25,7 +25,7 @@ namespace Avalonia.Controls
         /// </summary>
         //TODO Binding
         [AssignBinding]
-        [InheritDataTypeFromItems(nameof(DataGrid.Items), AncestorType = typeof(DataGrid))]
+        [InheritDataTypeFromItems(nameof(DataGrid.ItemsSource), AncestorType = typeof(DataGrid))]
         public virtual IBinding Binding
         {
             get

src/Avalonia.Controls.DataGrid/DataGridDataConnection.cs

@@ -122,9 +122,9 @@ namespace Avalonia.Controls
                 // We need to use the raw ItemsSource as opposed to DataSource because DataSource
                 // may be the ItemsSource wrapped in a collection view, in which case we wouldn't
                 // be able to take T to be the type if we're given IEnumerable<T>
-                if (_dataType == null && _owner.Items != null)
+                if (_dataType == null && _owner.ItemsSource != null)
                 {
-                    _dataType = _owner.Items.GetItemType();
+                    _dataType = _owner.ItemsSource.GetItemType();
                 }
                 return _dataType;
             }

src/Avalonia.Controls.DataGrid/DataGridTemplateColumn.cs

@@ -24,7 +24,7 @@ namespace Avalonia.Controls
                 (o, v) => o.CellTemplate = v);
 
         [Content]
-        [InheritDataTypeFromItems(nameof(DataGrid.Items), AncestorType = typeof(DataGrid))]
+        [InheritDataTypeFromItems(nameof(DataGrid.ItemsSource), AncestorType = typeof(DataGrid))]
         public IDataTemplate CellTemplate
         {
             get { return _cellTemplate; }
@@ -51,7 +51,7 @@ namespace Avalonia.Controls
         /// <remarks>
         /// If this property is <see langword="null"/> the column is read-only.
         /// </remarks>
-        [InheritDataTypeFromItems(nameof(DataGrid.Items), AncestorType = typeof(DataGrid))]
+        [InheritDataTypeFromItems(nameof(DataGrid.ItemsSource), AncestorType = typeof(DataGrid))]
         public IDataTemplate CellEditingTemplate
         {
             get => _cellEditingCellTemplate;

src/Avalonia.Diagnostics/Diagnostics/Views/ControlDetailsView.xaml

@@ -51,7 +51,7 @@
       
       <DataGrid 
                 x:Name="DataGrid"
-                Items="{Binding PropertiesView}"
+                ItemsSource="{Binding PropertiesView}"
                 Grid.Row="2"
                 BorderThickness="0"
                 RowBackground="Transparent"

tests/Avalonia.LeakTests/ControlTests.cs

@@ -51,7 +51,7 @@ namespace Avalonia.LeakTests
                     {
                         Content = new DataGrid
                         {
-                            Items = _observableCollection
+                            ItemsSource = _observableCollection
                         }
                     };