回答編集履歴

- 1点目

- xamlの間違いを直します。

- ```xaml

- <TextBlock x:Name="TextBlock_Result" Text="{Binding Path=printText.Result}"/>

- <TextBlock x:Name="TextBlock_Filename" Text="{Binding filename.Filename}"/>

- ```

- ↓

- ```xaml

- <TextBlock x:Name="TextBlock_Result" Text="{Binding Path=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

- ```C#

- 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);

- }

- }

- }

- ```

- 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);

- }

- }

- }

- ```