Merge pull request #5097 from AvaloniaUI/fix-compiledbinding-with-datagrid

Fix CompiledBinding usage with DataGrid

samples/ControlCatalog/Pages/DataGridPage.xaml

@@ -1,5 +1,5 @@
 <UserControl xmlns="https://github.com/avaloniaui"
-             xmlns:local="clr-namespace:ControlCatalog.Models;assembly=ControlCatalog"
+             xmlns:local="using:ControlCatalog.Models"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              x:Class="ControlCatalog.Pages.DataGridPage">
   <UserControl.Resources>
@@ -26,7 +26,8 @@
         <DataGrid Name="dataGrid1" Margin="12" CanUserResizeColumns="True" CanUserReorderColumns="True" CanUserSortColumns="True" HeadersVisibility="All">
           <DataGrid.Columns>
             <DataGridTextColumn Header="Country" Binding="{Binding Name}" Width="6*" />
-            <DataGridTextColumn Header="Region" Binding="{Binding Region}" Width="4*" />
+            <!-- CompiledBinding example of usage. -->
+            <DataGridTextColumn Header="Region" Binding="{CompiledBinding Region}" Width="4*" x:DataType="local:Country" />
             <DataGridTextColumn Header="Population" Binding="{Binding Population}" Width="3*" />
             <DataGridTextColumn Header="Area" Binding="{Binding Area}" Width="3*" />
             <DataGridTextColumn Header="GDP" Binding="{Binding GDP}" Width="3*" CellStyleClasses="gdp" />

samples/ControlCatalog/Pages/DataGridPage.xaml.cs

@@ -24,8 +24,10 @@ namespace ControlCatalog.Pages
             dg1.LoadingRow += Dg1_LoadingRow;
             dg1.Sorting += (s, a) =>
             {
-                var property = ((a.Column as DataGridBoundColumn)?.Binding as Binding).Path;
-                if (property == dataGridSortDescription.PropertyPath
+                var binding = (a.Column as DataGridBoundColumn)?.Binding as Binding;
+
+                if (binding?.Path is string property
+                    && property == dataGridSortDescription.PropertyPath
                     && !collectionView1.SortDescriptions.Contains(dataGridSortDescription))
                 {
                     collectionView1.SortDescriptions.Add(dataGridSortDescription);

src/Avalonia.Controls.DataGrid/DataGridBoundColumn.cs

@@ -10,7 +10,8 @@ using System.Reactive.Disposables;
 using System.Reactive.Subjects;
 using Avalonia.Reactive;
 using System.Diagnostics;
-using Avalonia.Controls.Utils; 
+using Avalonia.Controls.Utils;
+using Avalonia.Markup.Xaml.MarkupExtensions;
 
 namespace Avalonia.Controls
 {
@@ -47,14 +48,15 @@ namespace Avalonia.Controls
 
                     if (_binding != null)
                     {
-                        if(_binding is Avalonia.Data.Binding binding)
+                        if(_binding is BindingBase binding)
                         {
                             if (binding.Mode == BindingMode.OneWayToSource)
                             {
                                 throw new InvalidOperationException("DataGridColumn doesn't support BindingMode.OneWayToSource. Use BindingMode.TwoWay instead.");
                             }
 
-                            if (!String.IsNullOrEmpty(binding.Path) && binding.Mode == BindingMode.Default)
+                            var path = (binding as Binding)?.Path ?? (binding as CompiledBindingExtension)?.Path.ToString();
+                            if (!string.IsNullOrEmpty(path) && binding.Mode == BindingMode.Default)
                             {
                                 binding.Mode = BindingMode.TwoWay;
                             } 
@@ -136,13 +138,16 @@ namespace Avalonia.Controls
         internal void SetHeaderFromBinding()
         {
             if (OwningGrid != null && OwningGrid.DataConnection.DataType != null
-                && Header == null && Binding != null && Binding is Binding binding
-                && !String.IsNullOrWhiteSpace(binding.Path))
+                && Header == null && Binding != null && Binding is BindingBase binding)
             {
-                string header = OwningGrid.DataConnection.DataType.GetDisplayName(binding.Path);
-                if (header != null)
+                var path = (binding as Binding)?.Path ?? (binding as CompiledBindingExtension)?.Path.ToString();
+                if (!string.IsNullOrWhiteSpace(path))
                 {
-                    Header = header;
+                    var header = OwningGrid.DataConnection.DataType.GetDisplayName(path);
+                    if (header != null)
+                    {
+                        Header = header;
+                    }
                 }
             }
         }

src/Avalonia.Controls.DataGrid/DataGridColumn.cs

@@ -12,6 +12,7 @@ using System;
 using System.Linq;
 using System.Diagnostics;
 using Avalonia.Controls.Utils;
+using Avalonia.Markup.Xaml.MarkupExtensions;
 
 namespace Avalonia.Controls
 {
@@ -1033,13 +1034,16 @@ namespace Avalonia.Controls
 
             if (String.IsNullOrEmpty(result))
             {
-
-                if(this is DataGridBoundColumn boundColumn && 
-                    boundColumn.Binding != null &&
-                    boundColumn.Binding is Binding binding &&
-                    binding.Path != null)
+                if (this is DataGridBoundColumn boundColumn)
                 {
-                    result = binding.Path;
+                    if (boundColumn.Binding is Binding binding)
+                    {
+                        result = binding.Path;
+                    }
+                    else if (boundColumn.Binding is CompiledBindingExtension compiledBinding)
+                    {
+                        result = compiledBinding.Path.ToString();
+                    }
                 }
             }
 

src/Avalonia.Controls.DataGrid/DataGridColumns.cs

@@ -5,6 +5,7 @@
 
 using Avalonia.Controls.Utils;
 using Avalonia.Data;
+using Avalonia.Markup.Xaml.MarkupExtensions;
 using Avalonia.Utilities;
 using System;
 using System.Collections.Generic;
@@ -141,9 +142,9 @@ namespace Avalonia.Controls
             Debug.Assert(dataGridColumn != null);
 
             if (dataGridColumn is DataGridBoundColumn dataGridBoundColumn && 
-                dataGridBoundColumn.Binding is Binding binding)
+                dataGridBoundColumn.Binding is BindingBase binding)
             {
-                string path = binding.Path;
+                var path = (binding as Binding)?.Path ?? (binding as CompiledBindingExtension)?.Path.ToString();
 
                 if (string.IsNullOrWhiteSpace(path))
                 {

src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/CompiledBindings/CompiledBindingPath.cs

@@ -72,7 +72,7 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings
         internal object RawSource { get; }
 
         public override string ToString()
-            => string.Concat(_elements.Select(e => e.ToString()));
+            => string.Concat(_elements);
     }
 
     public class CompiledBindingPathBuilder
@@ -88,7 +88,7 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings
 
         public CompiledBindingPathBuilder Property(IPropertyInfo info, Func<WeakReference<object>, IPropertyInfo, IPropertyAccessor> accessorFactory)
         {
-            _elements.Add(new PropertyElement(info, accessorFactory));
+            _elements.Add(new PropertyElement(info, accessorFactory, _elements.Count == 0));
             return this;
         }
 
@@ -161,10 +161,13 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings
 
     internal class PropertyElement : ICompiledBindingPathElement
     {
-        public PropertyElement(IPropertyInfo property, Func<WeakReference<object>, IPropertyInfo, IPropertyAccessor> accessorFactory)
+        private readonly bool _isFirstElement;
+
+        public PropertyElement(IPropertyInfo property, Func<WeakReference<object>, IPropertyInfo, IPropertyAccessor> accessorFactory, bool isFirstElement)
         {
             Property = property;
             AccessorFactory = accessorFactory;
+            _isFirstElement = isFirstElement;
         }
 
         public IPropertyInfo Property { get; }
@@ -172,7 +175,7 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings
         public Func<WeakReference<object>, IPropertyInfo, IPropertyAccessor> AccessorFactory { get; }
 
         public override string ToString()
-            => $".{Property.Name}";
+            => _isFirstElement ? Property.Name : $".{Property.Name}";
     }
 
     internal interface IStronglyTypedStreamElement : ICompiledBindingPathElement