.NET: WPF Binding对数据的校验和转换

一。校验

一般需要对target上的值进行校验。

xaml:

1 <Window x:Class="WpfApplication1.MainWindow"
2         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
3         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
4         Title="Simple Binding" Height="135" Width="300">
5     <StackPanel x:Name="stackPanel" Background="LightBlue">
6         <TextBox x:Name="textBox1" Margin="5" />
7         <Slider x:Name="slider1" Minimum="0" Maximum="100" Margin="5" />
8     </StackPanel>
9 </Window>

写一个RangeValidationRule类

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 using System.Windows.Controls;
 7
 8 namespace WpfApplication1
 9 {
10     class RangeValidationRule : ValidationRule
11     {
12         public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
13         {
14             double d = 0;
15             if (double.TryParse(value.ToString(), out d))
16             {
17                 if (d >= 0 && d <= 100)
18                 {
19                     return new ValidationResult(true, null);
20                 }
21             }
22             return new ValidationResult(false, "Validation Failed");
23         }
24     }
25 }

再在xaml.cs里这么写

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 using System.Windows;
 7 using System.Windows.Controls;
 8 using System.Windows.Data;
 9 using System.Windows.Documents;
10 using System.Windows.Input;
11 using System.Windows.Media;
12 using System.Windows.Media.Imaging;
13 using System.Windows.Navigation;
14 using System.Windows.Shapes;
15 using System.Data;
16 using MySql.Data;
17 using MySql.Data.Entity;
18 using MySql.Data.MySqlClient;
19 using System.Xml;
20 using System.Xml.Linq;
21
22 namespace WpfApplication1
23 {
24     /// <summary>
25     /// Interaction logic for MainWindow.xaml
26     /// </summary>
27     public partial class MainWindow : Window
28     {
29         public MainWindow()
30         {
31             InitializeComponent();
32             Binding binding = new Binding("Value") { Source = this.slider1 };
33             binding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
34             RangeValidationRule rvr = new RangeValidationRule();
35             binding.ValidationRules.Add(rvr);
36             this.textBox1.SetBinding(TextBox.TextProperty, binding);
37         }
38
39     }
40 }

如果在textbox里的数不在0到100范围里，其边框就会变成红色

在这里Source是slider1，target是textBox1。一般来说Source的数据都是正确的，而target的数据可能是用户输入的，有可能是不正确的，所以需要校验。上面的代码是不会对Source更新数据时进行校验的，如果说Source的数据也有可能有问题，我们就需要将校验条件的ValidatesOnTargetUpdated属性设为true

xaml：

1 <Window x:Class="WpfApplication1.MainWindow"
2         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
3         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
4         Title="Simple Binding" Height="135" Width="300">
5     <StackPanel x:Name="stackPanel" Background="LightBlue">
6         <TextBox x:Name="textBox1" Margin="5" />
7         <Slider x:Name="slider1" Minimum="-10" Maximum="110" Margin="5" />
8     </StackPanel>
9 </Window>

xaml.cs:

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 using System.Windows;
 7 using System.Windows.Controls;
 8 using System.Windows.Data;
 9 using System.Windows.Documents;
10 using System.Windows.Input;
11 using System.Windows.Media;
12 using System.Windows.Media.Imaging;
13 using System.Windows.Navigation;
14 using System.Windows.Shapes;
15 using System.Data;
16 using MySql.Data;
17 using MySql.Data.Entity;
18 using MySql.Data.MySqlClient;
19 using System.Xml;
20 using System.Xml.Linq;
21
22 namespace WpfApplication1
23 {
24     /// <summary>
25     /// Interaction logic for MainWindow.xaml
26     /// </summary>
27     public partial class MainWindow : Window
28     {
29         public MainWindow()
30         {
31             InitializeComponent();
32             Binding binding = new Binding("Value") { Source = this.slider1 };
33             binding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
34             RangeValidationRule rvr = new RangeValidationRule();
35             rvr.ValidatesOnTargetUpdated = true;
36             binding.ValidationRules.Add(rvr);
37             this.textBox1.SetBinding(TextBox.TextProperty, binding);
38         }
39
40     }
41 }

当slider的值小于0或者大于100时，textbox的边框就会变红，数字是不在0到100内的

如果要显示这个错误信息，需要加入侦听器，具体代码如下：

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 using System.Windows;
 7 using System.Windows.Controls;
 8 using System.Windows.Data;
 9 using System.Windows.Documents;
10 using System.Windows.Input;
11 using System.Windows.Media;
12 using System.Windows.Media.Imaging;
13 using System.Windows.Navigation;
14 using System.Windows.Shapes;
15 using System.Data;
16 using MySql.Data;
17 using MySql.Data.Entity;
18 using MySql.Data.MySqlClient;
19 using System.Xml;
20 using System.Xml.Linq;
21
22 namespace WpfApplication1
23 {
24     /// <summary>
25     /// Interaction logic for MainWindow.xaml
26     /// </summary>
27     public partial class MainWindow : Window
28     {
29         public MainWindow()
30         {
31             InitializeComponent();
32             Binding binding = new Binding("Value") { Source = this.slider1 };
33             binding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
34             RangeValidationRule rvr = new RangeValidationRule();
35             rvr.ValidatesOnTargetUpdated = true;
36             binding.ValidationRules.Add(rvr);
37             binding.NotifyOnValidationError = true;
38             this.textBox1.SetBinding(TextBox.TextProperty, binding);
39             this.textBox1.AddHandler(Validation.ErrorEvent, new RoutedEventHandler(this.ValidationError));
40         }
41
42         private void ValidationError(object sender, RoutedEventArgs e)
43         {
44             if (Validation.GetErrors(this.textBox1).Count > 0)
45             {
46                 this.textBox1.ToolTip = Validation.GetErrors(this.textBox1)[0].ErrorContent.ToString();
47             }
48         }
49     }
50 }

二。 转换