实现 WPF 文本框的验证
本文关键字：验证 文本 WPF 实现 | 更新日期: 2023-09-27 18:36:43
我有3个文本框（Id1，Name和Salary）。 Id 和 Salary 应包含整数，Name应仅包含字符。我需要对我的文本框进行验证，当我输入错误的字符或整数时，它应该显示错误。这也可以在没有代码隐藏的 Xaml 中完成吗？请帮助我输入所需的代码
这是 Xaml 代码：
<TextBox Name="tb1" HorizontalAlignment="Left" Height="20" Margin="60,10,0,0" TextWrapping="NoWrap" Text="{Binding SelectedItem.Id,ElementName=dgsample}" VerticalAlignment="Top" Width="100" />
<TextBox Name="tb2" HorizontalAlignment="Left" Height="20" Margin="60,60,0,0" TextWrapping="NoWrap" Text="{Binding SelectedItem.Name, ElementName=dgsample}" VerticalAlignment="Top" Width="100"/>
<TextBox Name="tb3" HorizontalAlignment="Left" Height="20" Margin="60,110,0,0" TextWrapping="NoWrap" Text="{Binding SelectedItem.Salary, ElementName=dgsample}" VerticalAlignment="Top" Width="100"/>
有 3 种方法可以实现验证：
- 验证规则
- INotifyDataErrorInfo 的实现
- IDataErrorInfo 的实现
验证规则示例：
public class NumericValidationRule : ValidationRule
{
public Type ValidationType { get; set; }
public override ValidationResult Validate(object value, CultureInfo cultureInfo)
{
string strValue = Convert.ToString(value);
if (string.IsNullOrEmpty(strValue))
return new ValidationResult(false, $"Value cannot be coverted to string.");
bool canConvert = false;
switch (ValidationType.Name)
{
case "Boolean":
bool boolVal = false;
canConvert = bool.TryParse(strValue, out boolVal);
return canConvert ? new ValidationResult(true, null) : new ValidationResult(false, $"Input should be type of boolean");
case "Int32":
int intVal = 0;
canConvert = int.TryParse(strValue, out intVal);
return canConvert ? new ValidationResult(true, null) : new ValidationResult(false, $"Input should be type of Int32");
case "Double":
double doubleVal = 0;
canConvert = double.TryParse(strValue, out doubleVal);
return canConvert ? new ValidationResult(true, null) : new ValidationResult(false, $"Input should be type of Double");
case "Int64":
long longVal = 0;
canConvert = long.TryParse(strValue, out longVal);
return canConvert ? new ValidationResult(true, null) : new ValidationResult(false, $"Input should be type of Int64");
default:
throw new InvalidCastException($"{ValidationType.Name} is not supported");
}
}
}
XAML：
非常重要：不要忘记设置ValidatesOnTargetUpdated="True"没有这个定义就不起作用。
<TextBox x:Name="Int32Holder"
IsReadOnly="{Binding IsChecked,ElementName=CheckBoxEditModeController,Converter={converters:BooleanInvertConverter}}"
Style="{StaticResource ValidationAwareTextBoxStyle}"
VerticalAlignment="Center">
<!--Text="{Binding Converter={cnv:TypeConverter}, ConverterParameter='Int32', Path=ValueToEdit.Value, UpdateSourceTrigger=PropertyChanged, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}"-->
<TextBox.Text>
<Binding Path="Name"
Mode="TwoWay"
UpdateSourceTrigger="PropertyChanged"
Converter="{cnv:TypeConverter}"
ConverterParameter="Int32"
ValidatesOnNotifyDataErrors="True"
ValidatesOnDataErrors="True"
NotifyOnValidationError="True">
<Binding.ValidationRules>
<validationRules:NumericValidationRule ValidationType="{x:Type system:Int32}"
ValidatesOnTargetUpdated="True" />
</Binding.ValidationRules>
</Binding>
</TextBox.Text>
<!--NumericValidationRule-->
</TextBox>
INotifyDataErrorInfo 示例：
public abstract class ViewModelBase : INotifyPropertyChanged, INotifyDataErrorInfo
{
#region INotifyPropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
ValidateAsync();
}
#endregion
public virtual void OnLoaded()
{
}
#region INotifyDataErrorInfo
private ConcurrentDictionary<string, List<string>> _errors = new ConcurrentDictionary<string, List<string>>();
public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;
public void OnErrorsChanged(string propertyName)
{
var handler = ErrorsChanged;
if (handler != null)
handler(this, new DataErrorsChangedEventArgs(propertyName));
}
public IEnumerable GetErrors(string propertyName)
{
List<string> errorsForName;
_errors.TryGetValue(propertyName, out errorsForName);
return errorsForName;
}
public bool HasErrors
{
get { return _errors.Any(kv => kv.Value != null && kv.Value.Count > 0); }
}
public Task ValidateAsync()
{
return Task.Run(() => Validate());
}
private object _lock = new object();
public void Validate()
{
lock (_lock)
{
var validationContext = new ValidationContext(this, null, null);
var validationResults = new List<ValidationResult>();
Validator.TryValidateObject(this, validationContext, validationResults, true);
foreach (var kv in _errors.ToList())
{
if (validationResults.All(r => r.MemberNames.All(m => m != kv.Key)))
{
List<string> outLi;
_errors.TryRemove(kv.Key, out outLi);
OnErrorsChanged(kv.Key);
}
}
var q = from r in validationResults
from m in r.MemberNames
group r by m into g
select g;
foreach (var prop in q)
{
var messages = prop.Select(r => r.ErrorMessage).ToList();
if (_errors.ContainsKey(prop.Key))
{
List<string> outLi;
_errors.TryRemove(prop.Key, out outLi);
}
_errors.TryAdd(prop.Key, messages);
OnErrorsChanged(prop.Key);
}
}
}
#endregion
}
查看模型实现：
public class MainFeedViewModel : BaseViewModel//, IDataErrorInfo
{
private ObservableCollection<FeedItemViewModel> _feedItems;
[XmlIgnore]
public ObservableCollection<FeedItemViewModel> FeedItems
{
get
{
return _feedItems;
}
set
{
_feedItems = value;
OnPropertyChanged("FeedItems");
}
}
[XmlIgnore]
public ObservableCollection<FeedItemViewModel> FilteredFeedItems
{
get
{
if (SearchText == null) return _feedItems;
return new ObservableCollection<FeedItemViewModel>(_feedItems.Where(x => x.Title.ToUpper().Contains(SearchText.ToUpper())));
}
}
private string _title;
[Required]
[StringLength(20)]
//[CustomNameValidationRegularExpression(5, 20)]
[CustomNameValidationAttribute(3, 20)]
public string Title
{
get { return _title; }
set
{
_title = value;
OnPropertyChanged("Title");
}
}
private string _url;
[Required]
[StringLength(200)]
[Url]
//[CustomValidation(typeof(MainFeedViewModel), "UrlValidation")]
/// <summary>
/// Validation of URL should be with custom method like the one that implemented below, or with
/// </summary>
public string Url
{
get { return _url; }
set
{
_url = value;
OnPropertyChanged("Url");
}
}
public MainFeedViewModel(string url, string title)
{
Title = title;
Url = url;
}
/// <summary>
///
/// </summary>
public MainFeedViewModel()
{
}
public MainFeedViewModel(ObservableCollection<FeedItemViewModel> feeds)
{
_feedItems = feeds;
}
private string _searchText;
[XmlIgnore]
public string SearchText
{
get { return _searchText; }
set
{
_searchText = value;
OnPropertyChanged("SearchText");
OnPropertyChanged("FilteredFeedItems");
}
}
#region Data validation local
/// <summary>
/// Custom URL validation method
/// </summary>
/// <param name="obj"></param>
/// <param name="context"></param>
/// <returns></returns>
public static ValidationResult UrlValidation(object obj, ValidationContext context)
{
var vm = (MainFeedViewModel)context.ObjectInstance;
if (!Uri.IsWellFormedUriString(vm.Url, UriKind.Absolute))
{
return new ValidationResult("URL should be in valid format", new List<string> { "Url" });
}
return ValidationResult.Success;
}
#endregion
}
XAML：
<UserControl x:Class="RssReaderTool.Views.AddNewFeedDialogView"
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"
mc:Ignorable="d"
d:DesignHeight="300"
d:DesignWidth="300">
<FrameworkElement.Resources>
<Style TargetType="{x:Type TextBox}">
<Setter Property="Validation.ErrorTemplate">
<Setter.Value>
<ControlTemplate x:Name="TextErrorTemplate">
<DockPanel LastChildFill="True">
<AdornedElementPlaceholder>
<Border BorderBrush="Red"
BorderThickness="2" />
</AdornedElementPlaceholder>
<TextBlock FontSize="20"
Foreground="Red">*?*</TextBlock>
</DockPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="Validation.HasError"
Value="True">
<Setter Property="ToolTip"
Value="{Binding RelativeSource=
{x:Static RelativeSource.Self},
Path=(Validation.Errors)[0].ErrorContent}"></Setter>
</Trigger>
</Style.Triggers>
</Style>
<!--<Style TargetType="{x:Type TextBox}">
<Style.Triggers>
<Trigger Property="Validation.HasError"
Value="true">
<Setter Property="ToolTip"
Value="{Binding RelativeSource={x:Static RelativeSource.Self},
Path=(Validation.Errors)[0].ErrorContent}" />
</Trigger>
</Style.Triggers>
</Style>-->
</FrameworkElement.Resources>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="5" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="5" />
<RowDefinition Height="Auto" />
<RowDefinition Height="5" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<TextBlock Text="Feed Name"
ToolTip="Display" />
<TextBox Text="{Binding MainFeedViewModel.Title,UpdateSourceTrigger=PropertyChanged,ValidatesOnNotifyDataErrors=True,ValidatesOnDataErrors=True}"
Grid.Column="2" />
<TextBlock Text="Feed Url"
Grid.Row="2" />
<TextBox Text="{Binding MainFeedViewModel.Url,UpdateSourceTrigger=PropertyChanged,ValidatesOnNotifyDataErrors=True,ValidatesOnDataErrors=True}"
Grid.Column="2"
Grid.Row="2" />
</Grid>
</UserControl>
IDataErrorInfo：
查看模型：
public class OperationViewModel : ViewModelBase, IDataErrorInfo
{
private const int ConstCodeMinValue = 1;
private readonly IEventAggregator _eventAggregator;
private OperationInfoDefinition _operation;
private readonly IEntityFilterer _contextFilterer;
private OperationDescriptionViewModel _description;
public long Code
{
get { return _operation.Code; }
set
{
if (SetProperty(value, _operation.Code, o => _operation.Code = o))
{
UpdateDescription();
}
}
}
public string Description
{
get { return _operation.Description; }
set
{
if (SetProperty(value, _operation.Description, o => _operation.Description = o))
{
UpdateDescription();
}
}
}
public string FriendlyName
{
get { return _operation.FriendlyName; }
set
{
if (SetProperty(value, _operation.FriendlyName, o => _operation.FriendlyName = o))
{
UpdateDescription();
}
}
}
public int Timeout
{
get { return _operation.Timeout; }
set
{
if (SetProperty(value, _operation.Timeout, o => _operation.Timeout = o))
{
UpdateDescription();
}
}
}
public string Category
{
get { return _operation.Category; }
set
{
if (SetProperty(value, _operation.Category, o => _operation.Category = o))
{
UpdateDescription();
}
}
}
public bool IsManual
{
get { return _operation.IsManual; }
set
{
if (SetProperty(value, _operation.IsManual, o => _operation.IsManual = o))
{
UpdateDescription();
}
}
}
void UpdateDescription()
{
//some code
}
#region Validation
#region IDataErrorInfo
public ValidationResult Validate()
{
return ValidationService.Instance.ValidateNumber(Code, ConstCodeMinValue, long.MaxValue);
}
public string this[string columnName]
{
get
{
var validation = ValidationService.Instance.ValidateNumber(Code, ConstCodeMinValue, long.MaxValue);
return validation.IsValid ? null : validation.ErrorContent.ToString();
}
}
public string Error
{
get
{
var result = Validate();
return result.IsValid ? null : result.ErrorContent.ToString();
}
}
#endregion
#endregion
}
XAML：
<controls:NewDefinitionControl x:Class="DiagnosticsDashboard.EntityData.Operations.Views.NewOperationView"
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:views="clr-namespace:DiagnosticsDashboard.EntityData.Operations.Views"
xmlns:controls="clr-namespace:DiagnosticsDashboard.Core.Controls;assembly=DiagnosticsDashboard.Core"
xmlns:c="clr-namespace:DiagnosticsDashboard.Core.Validation;assembly=DiagnosticsDashboard.Core"
mc:Ignorable="d">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="40" />
<RowDefinition Height="*" />
<RowDefinition Height="*" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Label Grid.Column="0"
Grid.Row="0"
Margin="5">Code:</Label>
<Label Grid.Column="0"
Grid.Row="1"
Margin="5">Description:</Label>
<Label Grid.Column="0"
Grid.Row="2"
Margin="5">Category:</Label>
<Label Grid.Column="0"
Grid.Row="3"
Margin="5">Friendly Name:</Label>
<Label Grid.Column="0"
Grid.Row="4"
Margin="5">Timeout:</Label>
<Label Grid.Column="0"
Grid.Row="5"
Margin="5">Is Manual:</Label>
<TextBox Grid.Column="1"
Text="{Binding Code,UpdateSourceTrigger=PropertyChanged,ValidatesOnDataErrors=True}"
Grid.Row="0"
Margin="5"/>
<TextBox Grid.Column="1"
Grid.Row="1"
Margin="5"
Text="{Binding Description}" />
<TextBox Grid.Column="1"
Grid.Row="2"
Margin="5"
Text="{Binding Category}" />
<TextBox Grid.Column="1"
Grid.Row="3"
Margin="5"
Text="{Binding FriendlyName}" />
<TextBox Grid.Column="1"
Grid.Row="4"
Margin="5"
Text="{Binding Timeout}" />
<CheckBox Grid.Column="1"
Grid.Row="5"
Margin="5"
IsChecked="{Binding IsManual}"
VerticalAlignment="Center" />
</Grid>
</controls:NewDefinitionControl>
您还可以
在视图模型中实现IDataErrorInfo，如下所示。如果你实现IDataErrorInfo，你可以在其中进行验证，而不是特定属性的 setter，然后每当出现错误时，返回一条错误消息，以便有错误的文本框周围有一个红色框，指示错误。
class ViewModel : INotifyPropertyChanged, IDataErrorInfo
{
private string m_Name = "Type Here";
public ViewModel()
{
}
public string Name
{
get
{
return m_Name;
}
set
{
if (m_Name != value)
{
m_Name = value;
OnPropertyChanged("Name");
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
public string Error
{
get { return "...."; }
}
/// <summary>
/// Will be called for each and every property when ever its value is changed
/// </summary>
/// <param name="columnName">Name of the property whose value is changed</param>
/// <returns></returns>
public string this[string columnName]
{
get
{
return Validate(columnName);
}
}
private string Validate(string propertyName)
{
// Return error message if there is error on else return empty or null string
string validationMessage = string.Empty;
switch (propertyName)
{
case "Name": // property name
// TODO: Check validiation condition
validationMessage = "Error";
break;
}
return validationMessage;
}
}
您必须在 XAML 中设置ValidatesOnDataErrors=True才能调用IDataErrorInfo的方法，如下所示：
<TextBox Text="{Binding Name, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}" />
若要仅使用 XAML 完成此操作，需要为各个属性添加验证规则。但我建议您使用代码隐藏方法。在代码中，在属性资源库中定义规范，并在不符合规范时引发异常。并使用错误模板在 UI 中向用户显示错误。你的 XAML 将如下所示
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<Style x:Key="CustomTextBoxTextStyle" TargetType="TextBox">
<Setter Property="Foreground" Value="Green" />
<Setter Property="MaxLength" Value="40" />
<Setter Property="Width" Value="392" />
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="True">
<Trigger.Setters>
<Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self},Path=(Validation.Errors)[0].ErrorContent}"/>
<Setter Property="Background" Value="Red"/>
</Trigger.Setters>
</Trigger>
</Style.Triggers>
</Style>
</Window.Resources>
<Grid>
<TextBox Name="tb2" Height="30" Width="400"
Text="{Binding Name, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, ValidatesOnExceptions=True}"
Style="{StaticResource CustomTextBoxTextStyle}"/>
</Grid>
代码隐藏：
public partial class MainWindow : Window
{
private ExampleViewModel m_ViewModel;
public MainWindow()
{
InitializeComponent();
m_ViewModel = new ExampleViewModel();
DataContext = m_ViewModel;
}
}
public class ExampleViewModel : INotifyPropertyChanged
{
private string m_Name = "Type Here";
public ExampleViewModel()
{
}
public string Name
{
get
{
return m_Name;
}
set
{
if (String.IsNullOrEmpty(value))
{
throw new Exception("Name can not be empty.");
}
if (value.Length > 12)
{
throw new Exception("name can not be longer than 12 charectors");
}
if (m_Name != value)
{
m_Name = value;
OnPropertyChanged("Name");
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
我已经实现了这个验证。但是你会被使用在代码后面。这是太多简单和最简单的方法。
XAML：对于名称验证，仅输入 A-Z 和 a-z 中的字符。
<TextBox x:Name="first_name_texbox" PreviewTextInput="first_name_texbox_PreviewTextInput" > </TextBox>
代码隐藏。
private void first_name_texbox_PreviewTextInput ( object sender, TextCompositionEventArgs e )
{
Regex regex = new Regex ( "[^a-zA-Z]+" );
if ( regex.IsMatch ( first_name_texbox.Text ) )
{
MessageBox.Show("Invalid Input !");
}
}
对于工资和 ID 验证，将正则表达式构造函数传递的值替换为 [0-9]+ 。这意味着您只能输入从 1 到无限的数字。
您还可以使用 [0-9]{1,4} 定义长度。这意味着您只能输入小于或等于 4 位数字。这个球拍的意思是{至少，多少个数字}。通过执行此操作，您可以在文本框中定义数字范围。
愿它对他人有所帮助。
XAML：
代码隐藏。
private void salary_texbox_PreviewTextInput ( object sender, TextCompositionEventArgs e )
{
Regex regex = new Regex ( "[^0-9]+" );
if ( regex.IsMatch ( salary_texbox.Text ) )
{
MessageBox.Show("Invalid Input !");
}
}
当谈到穆罕默德·迈赫迪的回答时，最好这样做：
private void salary_texbox_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
Regex regex = new Regex ( "[^0-9]+" );
if(regex.IsMatch(e.Text))
{
MessageBox.Show("Error");
}
}
因为当与TextCompositionEventArgs进行比较时，它也得到了最后一个字符，而与文本框。文本它没有。使用文本框，错误将显示在下一个插入的字符之后。
当我需要这样做时，我使用Binding.ValidationRules遵循Microsoft的示例，它第一次工作。
请参阅他们的文章如何：实现绑定验证：https://learn.microsoft.com/en-us/dotnet/desktop/wpf/data/how-to-implement-binding-validation?view=netframeworkdesktop-4.8
当谈到DiSaSteR的答案时，我注意到了不同的行为。 textBox.Text 显示 TextBox 中的文本，就像用户输入新字符之前一样，而 e.Text 显示用户刚刚输入的单个字符。一个挑战是这个字符可能不会附加到末尾，但它会入到卡雷特位置：
private void salary_texbox_PreviewTextInput(object sender, TextCompositionEventArgs e){
Regex regex = new Regex ( "[^0-9]+" );
string text;
if (textBox.CaretIndex==textBox.Text.Length) {
text = textBox.Text + e.Text;
} else {
text = textBox.Text.Substring(0, textBox.CaretIndex) + e.Text + textBox.Text.Substring(textBox.CaretIndex);
}
if(regex.IsMatch(text)){
MessageBox.Show("Error");
}
}