Question

我使用prism 6在WPF中开发应用程序。我尝试使用此命令更新日期时间。我尝试更新代码而没有任何成功。

编辑1：添加了前链接到Onedrive的代码

类：

 public class Employee : BindableBase
{
    private int _id;
    public int ID
    {
        get { return _id; }

        set
        {
            SetProperty(ref _id, value);
        }
    }

    private string _firstName ="YehudaEmp";

    public string FirstName
    {
        get { return _firstName; }
        set {SetProperty(ref _firstName , value); }
    }

    private string _lastName="DnaiEmp";
    public string LastName
    {
        get { return _lastName; }
        set
        {
            SetProperty(ref _lastName, value);
        }
    }

    private int _phone;
    public int Phone
    {
        get
        {
            return _phone;
        }

        set
        {
            SetProperty(ref _phone, value);
        }
    }

    private string _email;
    public string Email
    {
        get { return _email; }
        set
        {
            SetProperty(ref _email, value);
        }
    }

    private string _city;
    public string  City
    {
        get { return _city; }
        set
        {
            SetProperty(ref _city, value);
        }
    }

    private string _street;
    public string Street
    {
        get { return _street; }
        set
        {
            SetProperty(ref _street, value);
        }
    }


    private string _state;
    public string State
    {
        get { return _state; }
        set
        {
            SetProperty(ref _state, value);
        }
    }

    private DateTime? _lastUpdate;
    public DateTime? LastUpdate
    {
        get { return _lastUpdate; }
        set
        {
            SetProperty(ref _lastUpdate, value);
        }
    }     
}

public class EmployeeViewModel :BindableBase
{

    private Employee emop;


   public string FirstName
    {
        get { return emop.FirstName; }
        set
        {
            emop.FirstName = value;
        }

    }

    public string LastName
    {
        get { return emop.LastName; }
        set
        {
            emop.LastName = value;
        }
    }

    public DateTime? lastUpdated
    {
        get { return emop.LastUpdate; }
        set
        {
            emop.LastUpdate = value;
        }
    }

    public DelegateCommand updateCommand { get; set; }


    public EmployeeViewModel()
    {

       emop = new Employee();
        updateCommand = new DelegateCommand(Execute , canExecute).ObservesProperty(()=>FirstName).ObservesProperty(() =>LastName);
    }

    private bool canExecute()
    {
      return  !String.IsNullOrWhiteSpace(FirstName) && !String.IsNullOrWhiteSpace(LastName);
    }

    private void Execute()
    {

       lastUpdated = DateTime.Now;

    }
}

XAML：

<Grid>
    <StackPanel>
        <Grid >
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="200"/>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition Width="2*"/>

            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
                <RowDefinition/>
                <RowDefinition/>
                <RowDefinition/>
            </Grid.RowDefinitions>
            <TextBox Grid.Column="0" Grid.Row="0" Width="195" Height="30" Margin="5" Text="{Binding FirstName ,UpdateSourceTrigger=PropertyChanged}"/>
            <TextBox Grid.Column="0" Grid.Row="1" Width="195" Height="30" Margin="5" Text="{Binding LastName , UpdateSourceTrigger=PropertyChanged}"/>
            <TextBlock Text="{Binding lastUpdated,UpdateSourceTrigger=PropertyChanged}" Grid.Row="2" Grid.Column="1" FontSize="20"/>
            <Button Name="updatebtn" Grid.Row="3" Grid.Column="1" Width="Auto" Height="30" Margin="5" Content="update" Command="{Binding updateCommand,Mode=TwoWay}"/>
        </Grid>
    </StackPanel>
</Grid>

任何帮助？

Answer 1

假设您的视图模型是绑定到视图的EmployeeViewModel。

然后，您的问题是您的视图模型没有将PropertyChanged事件上升到视图中。您正在从模型中升级属性更改事件Employee并且视图未捕获这些事件。

您需要从视图模型中为视图引发事件以捕获它们。

方法BindableBase.SetProperty<T>引发PropertyChanged事件，因此您只需将SetProperty<T>类的Employee调用移至EmployeeViewModel类

因此，例如，您的lastUpdated绑定：

<TextBlock Text="{Binding lastUpdated,UpdateSourceTrigger=PropertyChanged}" Grid.Row="2" Grid.Column="1" FontSize="20"/>

视图模型中应该具有如下所示的相应属性：

private DateTime? m_lastUpdated;

public DateTime? lastUpdated
{
    get { return m_lastUpdated; }
    set { SetProperty<DateTime?>(ref m_lastUpdated, value);
}

从MVVM的角度来看，您通常不会从模型中引发PropertyChanged个事件（在您的情况下为Employee），唯一应该与视图通信的实体是视图模型（在你的情况下EmployeeViewModel。

WPF MVVM命令无法正常工作

1 个答案: