回答編集履歴

見直しキャンペーン中

2023/07/17 13:27

投稿

TN8001

スコア9855

test CHANGED Viewed

@@ -1,373 +1,185 @@
-1点目
+### 1点目
 xamlの間違いを直します。
-```xaml
+```xml
 <TextBlock x:Name="TextBlock_Result" Text="{Binding Path=printText.Result}"/>
 <TextBlock x:Name="TextBlock_Filename" Text="{Binding filename.Filename}"/>
 ```
 ↓
-```xaml
+```xml
-<TextBlock x:Name="TextBlock_Result" Text="{Binding Path=PrintText.Result}"/>
+<TextBlock x:Name="TextBlock_Result" Text="{Binding PrintText.Result}"/>
 <TextBlock x:Name="TextBlock_Filename" Text="{Binding PrintFilename.Filename}"/>
 ```
 バインディングのエラーは出力ウィンドウに出るだけで、特に止まったりしないので気が付きにくいです。
+```
+System.Windows.Data Error: 40 : BindingExpression path error: 'printText' property not found on 'object' ''MainWindowViewModel' (HashCode=64554036)'. BindingExpression:Path=printText.Result; DataItem='MainWindowViewModel' (HashCode=64554036); target element is 'TextBlock' (Name='TextBlock_Result'); target property is 'Text' (type 'String')
+System.Windows.Data Error: 40 : BindingExpression path error: 'filename' property not found on 'object' ''MainWindowViewModel' (HashCode=64554036)'. BindingExpression:Path=filename.Filename; DataItem='MainWindowViewModel' (HashCode=64554036); target element is 'TextBlock' (Name='TextBlock_Filename'); target property is 'Text' (type 'String')
+```
+のようなエラーが出ているはずです。
+### 2点目
+バインディングを使って表示したいのでしょうから、変更通知（`INotifyPropertyChanged`）の実装が必要になります（ViewModelBase・BindableBase・Observable等名前はいろいろだったりしますが、中身は大体同じで定型コードです）
+`MainWindowViewModel`の`PrintText`・`PrintFilename`を丸ごと入れ替えるような想定であればこんな感じになります。
+```cs
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+using System.Windows;
+using Microsoft.Win32;
+namespace Questions233114
+{
+    class PrintFilename
+    {
+        public string Filename { get; set; }
+    }
+    class PrintText
+    {
+        public string Result { get; set; }
+    }
+    class MainWindowViewModel : Observable
+    {
+        public PrintText PrintText { get => _PrintText; set => Set(ref _PrintText, value); }
+        private PrintText _PrintText;
+        public PrintFilename PrintFilename { get => _PrintFilename; set => Set(ref _PrintFilename, value); }
+        private PrintFilename _PrintFilename;
+        public MainWindowViewModel()
+        {
+            PrintText = new PrintText();
+            PrintFilename = new PrintFilename();
+        }
+    }
+    abstract class Observable : INotifyPropertyChanged
+    {
+        public event PropertyChangedEventHandler PropertyChanged;
+        protected bool Set<T>(ref T storage, T value, [CallerMemberName] string propertyName = null)
+        {
+            if(Equals(storage, value)) return false;
+            storage = value;
+            OnPropertyChanged(propertyName);
+            return true;
+        }
+        protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
+            => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+    }
+    public partial class MainWindow : Window
+    {
+        private readonly MainWindowViewModel vm;
+        public MainWindow()
+        {
+            InitializeComponent();
+            vm = new MainWindowViewModel();
+            DataContext = vm;
+            var printText = new PrintText { Result = "OK" };
+            vm.PrintText = printText;
+            MessageBox.Show(vm.PrintText.Result);
+        }
+        private void Data_Button_Click(object sender, RoutedEventArgs e)
+        {
+            var oFileDialog = new OpenFileDialog { Filter = "Excel (*.xlsx)|*.xlsx" };
+            if(oFileDialog.ShowDialog() == false)
+            {
+                return;
+            }
+            var filename = new PrintFilename { Filename = oFileDialog.FileName };
+            vm.PrintFilename = filename;
+            MessageBox.Show(vm.PrintFilename.Filename);
+        }
+    }
+}
 ```
-System.Windows.Data Error: 40 : BindingExpression path error: 'printText' property not found on 'object' ''MainWindowViewModel' (HashCode=64554036)'. BindingExpression:Path=printText.Result; DataItem='MainWindowViewModel' (HashCode=64554036); target element is 'TextBlock' (Name='TextBlock_Result'); target property is 'Text' (type 'String')
-System.Windows.Data Error: 40 : BindingExpression path error: 'filename' property not found on 'object' ''MainWindowViewModel' (HashCode=64554036)'. BindingExpression:Path=filename.Filename; DataItem='MainWindowViewModel' (HashCode=64554036); target element is 'TextBlock' (Name='TextBlock_Filename'); target property is 'Text' (type 'String')
-```
-のようなエラーが出ているはずです。
-2点目
-バインディングを使って表示したいのでしょうから、変更通知（INotifyPropertyChanged）の実装が必要になります。（ViewModelBase BindableBase Observable等名前はいろいろだったりしますが、中身は大体同じで定型コードです）
-MainWindowViewModelのPrintText・PrintFilenameを丸ごと入れ替えるような想定であれば
-```C#
+Filename・Resultを直接変えるのであればこんな感じになります。
+```cs
 using System.ComponentModel;
 using System.Runtime.CompilerServices;
 using System.Windows;
 using Microsoft.Win32;
 namespace Questions233114
 {
-    class PrintFilename
+    class PrintFilename : Observable
     {
+        public string Filename { get => _Filename; set => Set(ref _Filename, value); }
-        public string Filename { get; set; }
+        private string _Filename;
     }
-    class PrintText
+    class PrintText : Observable
     {
+        public string Result { get => _Result; set => Set(ref _Result, value); }
-        public string Result { get; set; }
+        private string _Result;
     }
-    class MainWindowViewModel : Observable
+    class MainWindowViewModel
     {
-        public PrintText PrintText { get => _PrintText; set => Set(ref _PrintText, value); }
+        public PrintText PrintText { get; private set; }
-        private PrintText _PrintText;
-        public PrintFilename PrintFilename { get => _PrintFilename; set => Set(ref _PrintFilename, value); }
-        private PrintFilename _PrintFilename;
+        public PrintFilename PrintFilename { get; private set; }
         public MainWindowViewModel()
         {
             PrintText = new PrintText();
             PrintFilename = new PrintFilename();
         }
     }
     abstract class Observable : INotifyPropertyChanged
     {
         public event PropertyChangedEventHandler PropertyChanged;
         protected bool Set<T>(ref T storage, T value, [CallerMemberName] string propertyName = null)
         {
             if(Equals(storage, value)) return false;
             storage = value;
             OnPropertyChanged(propertyName);
             return true;
         }
         protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
             => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
     }
     public partial class MainWindow : Window
     {
         private readonly MainWindowViewModel vm;
         public MainWindow()
         {
             InitializeComponent();
             vm = new MainWindowViewModel();
             DataContext = vm;
-            var printText = new PrintText { Result = "OK" };
-            vm.PrintText = printText;
-            MessageBox.Show(vm.PrintText.Result);
-        }
-        private void Data_Button_Click(object sender, RoutedEventArgs e)
-        {
-            var oFileDialog = new OpenFileDialog { Filter = "Excel (*.xlsx)|*.xlsx" };
-            if(oFileDialog.ShowDialog() == false)
-            {
-                return;
-            }
-            var filename = new PrintFilename { Filename = oFileDialog.FileName };
-            vm.PrintFilename = filename;
-            MessageBox.Show(vm.PrintFilename.Filename);
-        }
-    }
-}
-```
-こんな感じになります。
-Filename・Resultを直接変えるのであれば
-```C#
-using System.ComponentModel;
-using System.Runtime.CompilerServices;
-using System.Windows;
-using Microsoft.Win32;
-namespace Questions233114
-{
-    class PrintFilename : Observable
-    {
-        public string Filename { get => _Filename; set => Set(ref _Filename, value); }
-        private string _Filename;
-    }
-    class PrintText : Observable
-    {
-        public string Result { get => _Result; set => Set(ref _Result, value); }
-        private string _Result;
-    }
-    class MainWindowViewModel
-    {
-        public PrintText PrintText { get; private set; }
-        public PrintFilename PrintFilename { get; private set; }
-        public MainWindowViewModel()
-        {
-            PrintText = new PrintText();
-            PrintFilename = new PrintFilename();
-        }
-    }
-    abstract class Observable : INotifyPropertyChanged
-    {
-        public event PropertyChangedEventHandler PropertyChanged;
-        protected bool Set<T>(ref T storage, T value, [CallerMemberName] string propertyName = null)
-        {
-            if(Equals(storage, value)) return false;
-            storage = value;
-            OnPropertyChanged(propertyName);
-            return true;
-        }
-        protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
-            => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
-    }
-    public partial class MainWindow : Window
-    {
-        private readonly MainWindowViewModel vm;
-        public MainWindow()
-        {
-            InitializeComponent();
-            vm = new MainWindowViewModel();
-            DataContext = vm;
             vm.PrintText.Result = "OK";
             MessageBox.Show(vm.PrintText.Result);
         }
         private void Data_Button_Click(object sender, RoutedEventArgs e)
         {
             var oFileDialog = new OpenFileDialog { Filter = "Excel (*.xlsx)|*.xlsx" };
             if(oFileDialog.ShowDialog() == false)
             {
                 return;
             }
             vm.PrintFilename.Filename = oFileDialog.FileName;
             MessageBox.Show(vm.PrintFilename.Filename);
         }
     }
 }
 ```
-こんな感じになります。
 どちらのパターンもあり得ますが、どちらがいいかはこれだけだとちょっと判断できません。