使用WPF验证C＃中的文本框

Question

I have a window with some textboxes, comboxes and checkboxes. One of the textboxes need to be a number so I wanted to validate it. I searched through the internet and found a good tutorial . I tried to use it, but it seems that it doesn't work or I did something wrong and I just don't see what I did wrong. So I hope anyone here can say me what I'm doing wrong or an other solution to get it started. Here is the xaml of the window:

<Window x:Class="WpfApplication1.mainpanels.EditWorkAssignments"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:validators="clr-namespace:WpfApplication1.validationRules"
    Title="EditWorkAssignments" Height="225" Width="300">
<Window.Resources>
    <Style TargetType="{x:Type TextBox}">

        <Style.Triggers>
            <Trigger Property="Validation.HasError" Value="true">
                <Setter Property="ToolTip"
            Value="{Binding RelativeSource={RelativeSource Self}, 
                   Path=(Validation.Errors)[0].ErrorContent}"/>
            </Trigger>
        </Style.Triggers>
    </Style>
</Window.Resources>
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
        <RowDefinition Height="Auto" />
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="Auto" />
        <ColumnDefinition Width="200" />
    </Grid.ColumnDefinitions>
    <Label Grid.Row="0" Grid.Column="0" Content="Datum:"/>
    <Label Grid.Row="1" Grid.Column="0" Content="Projekt:"/>
    <Label Grid.Row="2" Grid.Column="0" Content="Ist Passiv:"/>
    <Label Grid.Row="3" Grid.Column="0" Content="Dauer:"/>
    <Label Grid.Row="4" Grid.Column="0" Content="Mitarbeiter:"/>
    <DatePicker Name="datePicker" Grid.Column="1" Grid.Row="0" Margin="3" />
    <ComboBox Name="comboBoxProject" Grid.Column="1" Grid.Row="1" Margin="3" />
    <CheckBox Name="checkBoxIsPassiv" Grid.Column="1" Grid.Row="2" Margin="3" />
    <TextBox Name="textBoxDauer" Grid.Column="1" Grid.Row="3" Margin="3" >
        <Binding Path="workAssignment.duration" UpdateSourceTrigger="PropertyChanged">
            <Binding.ValidationRules>
                <validators:IsNumberValidationRule ErrorMessage="Dauer has to be a number." />
            </Binding.ValidationRules>
        </Binding>
    </TextBox>
        <ComboBox Name="comboBoxEmployee" Grid.Column="1" Grid.Row="4" Margin="3">
        <ComboBox.ItemTemplate>
            <DataTemplate>
                <TextBlock>
                    <TextBlock.Text>
                        <MultiBinding StringFormat="{}{0} {1}">
                            <Binding Path="firstname"/>
                            <Binding Path="surname"/>
                        </MultiBinding>
                    </TextBlock.Text>
                </TextBlock>
            </DataTemplate>
        </ComboBox.ItemTemplate>
    </ComboBox>
    <Button Grid.Column="1" Grid.Row="5" HorizontalAlignment="Left" 
        MinWidth="80" Margin="3" Content="Save"  Click="saveHandler"/>
    <Button Grid.Column="1" Grid.Row="5" HorizontalAlignment="Right" 
        MinWidth="80" Margin="3" Content="Cancel" Click="cancelHandler" />
</Grid>

the code:

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApplication1.mainpanels
{
    /// <summary>
    /// Interaction logic for EditWorkAssignments.xaml
    /// </summary>
    public partial class EditWorkAssignments : Window
    {
        EmployeeManagementEntities1 context = null;
        public WorkAssignement workAssignment;

        public EditWorkAssignments(WorkAssignement workAssignment)
        {
            InitializeComponent();
            this.workAssignment = workAssignment;

            context = new EmployeeManagementEntities1();
            DbSet<Employee> employeeDb = context.Set<Employee>();
            employeeDb.Load();
            comboBoxEmployee.ItemsSource = employeeDb.Local;

            DbSet<Project> projectDb = context.Set<Project>();
            projectDb.Load();
            comboBoxProject.ItemsSource = projectDb.Local;
            comboBoxProject.DisplayMemberPath = "projectname";
        }


        private void saveHandler(object sender, RoutedEventArgs e)
        {
            Employee employee = (Employee)comboBoxEmployee.SelectedItem;
            Project project = (Project)comboBoxProject.SelectedItem;

            context.SaveChanges();
            Console.WriteLine("saveHandler");
        }

        private void cancelHandler(object sender, RoutedEventArgs e)
        {
            this.Close();
            Console.WriteLine("cancelHandler");
        }
    }
}

and the validationRule:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Controls;
using System.Globalization;
using System.Text.RegularExpressions;

namespace WpfApplication1.validationRules
{
    public class IsNumberValidationRule : ValidationRule
    {
        private string _errorMessage;

        public string ErrorMessage
        {
            get { return _errorMessage; }
            set { _errorMessage = value; }
        }

        public override ValidationResult Validate(object value,
            CultureInfo cultureInfo)
        {
            ValidationResult result = new ValidationResult(true, null);
            string inputString = (value ?? string.Empty).ToString();
            try
            {
                double.Parse(inputString);
            }
            catch(FormatException ex)
            {
                result = new ValidationResult(false, this.ErrorMessage);
            }
            return result;
        }
    }
}

Answer 1

You need to set up a ViewModel for the property bound to the textbox, textBoxDauer or create the property in your code behind, eg Duration. In that property then do the validation like this

public string Duration 
{
    get { return _duration ; }
    set
    {
        _name = value;
        if (String.IsNullOrEmpty(value) || Int32.TryParse(value))
        {
            throw new ArgumentException("Dauer has to be a number..");
        }
    }
}

This set method is what gets called by the UpdateSourceTrigger, if an exception is thrown it will propagate up the tree and everything should work as expected.

Hope it helps.

Answer 2

The solution to my problem was really easl. I just missed to set workassignment as my dataContext:

        this.DataContext = workAssignement;

Sarajog