wpf - 如何在 TextBox 与 WPF 中的 MVVM 绑定(bind)时设置 TextBox.Text 值

Question

我正在使用 WPF 表单，我想知道如何通过 TextBox 与 MVVM 绑定(bind)来设置 TextBox.Text 值。例如:TextBox.Text = "Hello"; 我想将此值设置为文本框，我的文本框如

 public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        txtCityName.Text = "Hello Vaibhav";
        this.DataContext = new MyTesting();

    }
}

我的 WPF 窗口窗体类:

下一个我的 Xaml:

 <Grid>
    <TextBox Name="txtCityName" Grid.Row="3" Grid.Column="1"   Text="{Binding CityName, UpdateSourceTrigger=PropertyChanged}" Height="40" Width="200"/>
</Grid>

接下来是我的模型:

internal class MyTesting : INotifyPropertyChanged
{
    private string _CityName;

    public MyTesting()
    {

    }
    public string CityName
    {
        get { return _CityName; }
        set { _CityName = value; OnPropertyChanged("CityName"); }
    }

    #region PropertyChangedEventHandler
    public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
    #endregion
    #region " RaisePropertyChanged Function "
    /// <summary>
    /// 
    /// </summary>
    /// <param name="propertyName"></param>
    private void RaisePropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new System.ComponentModel.PropertyChangedEventArgs(propertyName));

    }
    #endregion
}

但是 NULL 分配给了 TextBox 。如何解决这个问题

Answer 1

试试这个:

class AddressModel: INotifyPropertyChanged
{
        private string _cityName;
        public string CityName 
        {
        get {
              return _cityName; 
            }
        set {
              _cityName = value; 
              OnPropertyChanged("CityName");
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged(string property)
        {
            this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(property));
        }                           
}

在您的代码隐藏中:

AddressModel addressModel = new AddressModel();
addressModel.CityName = "YourCity";
this.dataContext = addressModel;

Xaml:

<TextBox Name="txtCityName" Grid.Row="3" Grid.Column="1" Text="{Binding CityName,UpdateSourceTrigger=PropertyChanged}">