我是WPF中的新手。我刚刚学会了InotifyPropertychanged,但我不知道我是否正确使用了它。
我有一个登录页,我将UserNametextbox的文本属性绑定到我的对象(我认为是视图模型)
<UserControl x:Class="DentalThesis.Pages.LoginPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mui="http://firstfloorsoftware.com/ModernUI"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="500">
<Grid Style="{StaticResource ContentRoot}">
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
</Grid.RowDefinitions>
<TextBlock Text="User Name: " Grid.Row="1" Grid.Column="0"/>
<TextBlock Text="Password: " Grid.Row="2" Grid.Column="0"/>
<TextBox x:Name="UserNameTextBox" Text="{Binding UserName}" Grid.Row="1" Grid.Column="1" PreviewKeyUp="UserNameTextBox_OnPreviewKeyUp"/>
<PasswordBox x:Name="LoginPasswordBox" Grid.Row="2" Grid.Column="1" PreviewKeyUp="LoginPasswordBox_OnPreviewKeyUp"/>
<TextBlock x:Name="NotificationTextBlock" Grid.Row="4" Grid.Column="0" Grid.ColumnSpan="2"
VerticalAlignment="Center"
Foreground="Red" HorizontalAlignment="Center"/>
<Button x:Name="LoginButton" Content="Login" Grid.Row="6" Grid.Column="0" Click="LoginButton_OnClick"/>
<Button x:Name="ExitButton" Content="Exit" Grid.Row="6" Grid.Column="1" Click="ExitButton_OnClick"/>
</Grid>
</UserControl>
我的代码中有一种方法,该方法验证了usernametextbox的文本。如果我单击loginbutton,代码很好,但是由于我也使用了该事件usernametextbox_onpreviewkeyup,只要插入点不留下usernametextbox,我的视图模型尚未更新,因此我的usermgr.entity.username的值是"而不是我在usernametextbox中输入的字符串。仅当我将插入点移动到某个位置
时,它才会更新模型。这是我登录页面的背后的代码:
public partial class LoginPage
{
UserMgr userMgr = new UserMgr();
public LoginPage()
{
InitializeComponent();
DataContext = userMgr.Entity;
IsVisibleChanged += AutoFocus;
}
void AutoFocus(object sender, DependencyPropertyChangedEventArgs e)
{
if ((bool)e.NewValue)
{
Dispatcher.BeginInvoke(
DispatcherPriority.ContextIdle,
new Action(() => UserNameTextBox.Focus()));
}
}
public void LoginMethod()
{
//LoginButton.Focus(); <-- this is a remedy, but I want to remove this
if (userMgr.AuthenticateUser(userMgr.Entity))
{
SessionHelper.FormChosen = ChosenForm.FormLogin;
NotificationTextBlock.Text = "";
Exiter();
}
else
{
NotificationTextBlock.Text = "Error login";
}
}
private void Exiter()
{
Window parentWindow = Window.GetWindow(this);
if (parentWindow != null) parentWindow.Close();
}
private void LoginButton_OnClick(object sender, RoutedEventArgs e)
{
LoginMethod();
}
private void ExitButton_OnClick(object sender, RoutedEventArgs e)
{
Exiter();
}
private void UserNameTextBox_OnPreviewKeyUp(object sender, KeyEventArgs e)
{
if (e.Key.ToString() == "Return")
{
LoginMethod();
}
}
private void LoginPasswordBox_OnPreviewKeyUp(object sender, KeyEventArgs e)
{
if (e.Key.ToString() == "Return")
{
LoginMethod();
}
}
}
如下所示:https://msdn.microsoft.com/en-us/library/ms754356(V=VS.110).aspx,绑定文本框的属性文本时,默认情况下,它仅在失去焦点时才更新目标属性。要更新用户时,您必须设置绑定到属性变化的属性updateSourCetrigger,例如:
<TextBox x:Name="UserNameTextBox" Text="{Binding UserName, UpdateSourceTrigger=PropertyChanged}" ... />
btw,假设您正在实现模式MVVM,因为您正在执行的登录之类的操作更清洁,而不是在后面的代码上使用命令而不是事件处理程序。我向您推荐这篇文章,可能很长,但有用:https://msdn.microsoft.com/en-us/magazine/dn237302.aspx