Question

hej，

我不知道如何解决我的问题。我想从我的TextBox验证用户输入，然后如果输入错误则更改我的标签的颜色。我需要验证我的Get和Set中的输入？或者这完全错了吗？

我的xaml代码：

<Label x:Name="lblEmail" Content="Email Adress" Foreground="{Binding EmailAdressValid}"/>
<TextBox x:Name="txtEmail" Text="{Binding EmailAdress, UpdateSourceTrigger=PropertyChanged}"/>

我的数据类：

public class MainData : INotifyPropertyChanged {

        private int _emailAdress;
        public int EmailAdress
        {
            get { return _emailAdress; }
            set
            {
                _emailAdress = value;
                OnPropertyChanged(nameof(EmailAdress));
            }
        }

        private System.Windows.Media.Brush _emailAdressValid;
        public System.Windows.Media.Brush EmailAdressValid
        {
            get { return _emailAdressValid; }
            set
            {
                if(_emailAdress.Contains("@")) {
                   _emailAdressValid = Brushes.Black;
                }
                else {
                    _emailAdressValid = Brushes.Red;
                }
                OnPropertyChanged(nameof(EmailAdressValid));
            }
        }
}

Answer 1

IMO您没有按照正确的方式在WPF中进行验证。我们IDataErrorInfo就是这样。请将this视为首发。

现在回答你的问题，你的代码说它永远不会更新错误画笔，直到你set它，你不会。实际上，您不需要EmailAdressValid属性中的setter。在视图中提供电子邮件地址时，只需拨打OnPropertyChanged即可。

public class MainData : INotifyPropertyChanged 
{
    private string _emailAdress;
    public string EmailAdress
    {
        get { return _emailAdress; }
        set
        {
            _emailAdress = value;
            OnPropertyChanged(nameof(EmailAdress));
            OnPropertyChanged(nameof(EmailAdressValid));
        }
    }

    private System.Windows.Media.Brush _emailAdressValid;
    public System.Windows.Media.Brush EmailAdressValid
    {
        get 
        { 
            if(_emailAdress.Contains("@"))
            {
               _emailAdressValid = Brushes.Black;
            }
            else 
            {
                _emailAdressValid = Brushes.Red;
            }

            return _emailAdressValid;
        }
    }
}

Answer 2

使用控件绑定功能直接将标签绑定到电子邮件输入文本框。然后使用值转换器验证电子邮件的值并返回所需的背景颜色。请参考以下代码以供参考：

<?php
//connecting to the database
define('DB_HOST', 'localhost');
define('DB_NAME', 'connected_car_1');
define('DB_USER','Maryam1');
define('DB_PASSWORD','telecom1213');

$con=mysql_connect(DB_HOST,DB_USER,DB_PASSWORD) or die("Failed to connect to MySQL: " . mysql_error());
$db=mysql_select_db(DB_NAME,$con) or die("Failed to connect to MySQL: " . mysql_error());

 $sql = "INSERT INTO connected_car_1.sensor (value) VALUES ('".$_GET["value"]."')";    

   // Execute SQL statement

  mysql_query($sql,$con);
mysql_close($con);
?>


Include this resource as static resource in xaml file and use in the binding as below


public class TextToBackgroundConverter : IValueConverter
{
    public object Convert(object value, Type targetType, 
        object parameter, CultureInfo culture)
    {
        // Validate the email text and retun background color of your choice 
    }
    public object ConvertBack(object value, Type targetType, 
        object parameter, CultureInfo culture)
    {
        // Not needed 
    }
}

用户输入验证绑定

2 个答案: