当我第一次加载窗口时，按钮是可见的并且验证中没有错误(没有红线圆形文本框)。
在文本框中键入值时，验证规则会正常工作。
如果可能的话，我希望在开始时隐藏按钮，并在我开始向框中输入文本时启动验证规则。
这是我到目前为止的代码。 xaml:
<TextBox x:Name="txtName" HorizontalAlignment="Left" Height="23" Margin="156,119,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120" Validation.ErrorTemplate="{StaticResource ValidationErrorTemplate}">
<TextBox.Text>
<Binding Path="Name" UpdateSourceTrigger="PropertyChanged" NotifyOnSourceUpdated="True">
<Binding.ValidationRules>
<local:ValidationTest/>
</Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>
<Button x:Name="btn1" Content="Button" HorizontalAlignment="Left" Margin="85,221,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click">
<Button.Style>
<Style TargetType="Button">
<Setter Property="Visibility" Value="Hidden"/>
<Style.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding Path=(Validation.HasError), ElementName=txtName}" Value="False"/>
</MultiDataTrigger.Conditions>
<Setter Property="Visibility" Value="Visible"></Setter>
</MultiDataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
我的验证逻辑:
class ValidationTest : ValidationRule
{
private int result;
public override ValidationResult Validate(object value, CultureInfo cultureInfo)
{
if (value == null || string.IsNullOrEmpty(value.ToString()))
{
return new ValidationResult(false, "Value cannot be empty.");
}
if (value.ToString().Length > 4)
{
return new ValidationResult(false, "Name cannot be more than 20 characters long.");
}
return ValidationResult.ValidResult;
}
}
我正在使用的错误模板:
<Window.Resources>
<Style TargetType="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>
<ControlTemplate x:Key="ValidationErrorTemplate">
<DockPanel>
<Border BorderBrush="Red" BorderThickness="1.5">
<AdornedElementPlaceholder x:Name="ErrorAdorner"></AdornedElementPlaceholder>
</Border>
</DockPanel>
</ControlTemplate>
</Window.Resources>
我尝试在窗口加载时使用 txtName.GetBindingExpression(TextBox.TextProperty).UpdateSource(); 更新绑定(bind)，但这显示了验证错误(文本框周围的红线)。但是，该按钮是隐藏的，那么有什么方法可以隐藏验证错误，直到用户在文本框中键入文本？
我的处理方式是否正确？
最佳答案
我知道我参加派对有点晚了，但我在想做同样的事情时遇到了这个问题。关于使用标志来控制何时执行验证，我唯一不喜欢的是您需要在代码中的某个位置设置 DoValidation 标志，我希望它有点更多“自动化”。
网上找了好几个例子，好像都是用 bool 标志的方法。我找到了 this MSDN Article并以此为基础，然后调整代码。
我想出了一个似乎非常有效的解决方案。简而言之，我所做的基本上是创建另一个 Dictionary 来跟踪:
- 何时应执行验证。
- 存储验证的状态(有效、无效)。
我只想在第一次更新后执行验证，所以首要任务是决定是否应该执行验证。 Validation 的第一次运行将参数存储在 Dictionary 中，然后下一次如果参数存在，它会执行验证并存储 true/false(无效/有效)结果。这也是告知模型是否已验证以及是否有效的便捷方式，因此我还添加了一个参数/标志以简单地返回是否有任何结果和验证状态。这对于绑定(bind)命令启用/禁用特别有用。
我是这样实现的:
基本属性验证模型:
public abstract class PropertyValidation : INotifyPropertyChanged, IDataErrorInfo
{
#region Fields
private readonly Dictionary<string, object> _values = new Dictionary<string, object>();
/// <summary>
/// This holds the list of validation results and controls when the validation should be
/// performed and if the validation is valid.
/// </summary>
private Dictionary<string, bool> _validationResults { get; set; } = new Dictionary<string, bool>();
#endregion
#region Protected
/// <summary>
/// Sets the value of a property.
/// </summary>
/// <typeparam name="T">The type of the property value.</typeparam>
/// <param name="propertySelector">Expression tree contains the property definition.</param>
/// <param name="value">The property value.</param>
protected void SetValue<T>(Expression<Func<T>> propertySelector, T value)
{
string propertyName = GetPropertyName(propertySelector);
SetValue<T>(propertyName, value);
}
/// <summary>
/// Sets the value of a property.
/// </summary>
/// <typeparam name="T">The type of the property value.</typeparam>
/// <param name="propertyName">The name of the property.</param>
/// <param name="value">The property value.</param>
protected void SetValue<T>(string propertyName, T value)
{
if (string.IsNullOrEmpty(propertyName))
{
throw new ArgumentException("Invalid property name", propertyName);
}
_values[propertyName] = value;
OnPropertyChanged(propertyName);
}
/// <summary>
/// Gets the value of a property.
/// </summary>
/// <typeparam name="T">The type of the property value.</typeparam>
/// <param name="propertySelector">Expression tree contains the property definition.</param>
/// <returns>The value of the property or default value if not exist.</returns>
protected T GetValue<T>(Expression<Func<T>> propertySelector)
{
string propertyName = GetPropertyName(propertySelector);
return GetValue<T>(propertyName);
}
/// <summary>
/// Gets the value of a property.
/// </summary>
/// <typeparam name="T">The type of the property value.</typeparam>
/// <param name="propertyName">The name of the property.</param>
/// <returns>The value of the property or default value if not exist.</returns>
protected T GetValue<T>(string propertyName)
{
if (string.IsNullOrEmpty(propertyName))
{
throw new ArgumentException("Invalid property name", propertyName);
}
object value;
if (!_values.TryGetValue(propertyName, out value))
{
value = default(T);
_values.Add(propertyName, value);
}
return (T)value;
}
/// <summary>
/// Validates current instance properties using Data Annotations.
/// </summary>
/// <param name="propertyName">This instance property to validate.</param>
/// <returns>Relevant error string on validation failure or <see cref="System.String.Empty"/> on validation success.</returns>
protected virtual string OnValidate(string propertyName)
{
string error = string.Empty;
if (string.IsNullOrEmpty(propertyName))
{
throw new ArgumentException("Invalid property name", propertyName);
}
//Check if the Field has been added, this keeps track of when the validation
//is performed.
if (_validationResults.Any(x => x.Key == propertyName))
{
var value = GetValue(propertyName);
var results = new List<System.ComponentModel.DataAnnotations.ValidationResult>(1);
var result = Validator.TryValidateProperty(
value,
new ValidationContext(this, null, null)
{
MemberName = propertyName
},
results);
if (!result)
{
var validationResult = results.First();
error = validationResult.ErrorMessage;
//Store a true result in the validation to set the error.
_validationResults[propertyName] = true;
}
else
{
//If the Validation has been run and not invalid make sure the
//paramter in the list is cleared, otherwise validation would
//always return invalid once it is invalidated.
_validationResults[propertyName] = false;
}
}
else
{
//This is the first run of the Validation, simply store the paramter
//in the validation list and wait until next time to validate.
_validationResults.Add(propertyName, true);
}
//Notify that things have changed
OnPropertyChanged("IsValid");
//Return the actual result
return error;
}
#endregion
#region Public
/// <summary>
/// This returns if the Validation is Valid or not
/// </summary>
/// <returns>True if the Validation has been perfomed and if there are not
/// true values. Will return false until the validation has been done once.</returns>
public bool IsValid {
get { return (!_validationResults.Any(x => x.Value) && (_validationResults.Count > 0)); }
}
/// <summary>
/// Clears/Reset the Validation
/// </summary>
public void ClearValidation()
{
_validationResults.Clear();
}
#endregion
#region Change Notification
/// <summary>
/// Raised when a property on this object has a new value.
/// </summary>
public event PropertyChangedEventHandler PropertyChanged;
/// <summary>
/// Raises this object's PropertyChanged event.
/// </summary>
/// <param name="propertyName">The property that has a new value.</param>
protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
this.VerifyPropertyName(propertyName);
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
{
var e = new PropertyChangedEventArgs(propertyName);
handler(this, e);
}
}
protected void OnPropertyChanged<T>(Expression<Func<T>> propertySelector)
{
var propertyChanged = PropertyChanged;
if (propertyChanged != null)
{
string propertyName = GetPropertyName(propertySelector);
propertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
#endregion // IOnPropertyChanged Members
#region Data Validation
string IDataErrorInfo.Error {
get {
throw new NotSupportedException("IDataErrorInfo.Error is not supported, use IDataErrorInfo.this[propertyName] instead.");
}
}
string IDataErrorInfo.this[string propertyName] {
get {
return OnValidate(propertyName);
}
}
#endregion
#region Privates
private string GetPropertyName(LambdaExpression expression)
{
var memberExpression = expression.Body as MemberExpression;
if (memberExpression == null)
{
throw new InvalidOperationException();
}
return memberExpression.Member.Name;
}
private object GetValue(string propertyName)
{
object value;
if (!_values.TryGetValue(propertyName, out value))
{
var propertyDescriptor = TypeDescriptor.GetProperties(GetType()).Find(propertyName, false);
if (propertyDescriptor == null)
{
throw new ArgumentException("Invalid property name", propertyName);
}
value = propertyDescriptor.GetValue(this);
_values.Add(propertyName, value);
}
return value;
}
#endregion
#region Debugging
/// <summary>
/// Warns the developer if this object does not have
/// a public property with the specified name. This
/// method does not exist in a Release build.
/// </summary>
[Conditional("DEBUG")]
[DebuggerStepThrough]
public void VerifyPropertyName(string propertyName)
{
// Verify that the property name matches a real,
// public, instance property on this object.
if (TypeDescriptor.GetProperties(this)[propertyName] == null)
{
string msg = "Invalid property name: " + propertyName;
if (this.ThrowOnInvalidPropertyName)
throw new Exception(msg);
else
Debug.Fail(msg);
}
}
/// <summary>
/// Returns whether an exception is thrown, or if a Debug.Fail() is used
/// when an invalid property name is passed to the VerifyPropertyName method.
/// The default value is false, but subclasses used by unit tests might
/// override this property's getter to return true.
/// </summary>
protected virtual bool ThrowOnInvalidPropertyName { get; private set; }
#endregion // Debugging Aides
}
型号:
public class MyModel : PropertyValidation
{
[Required(ErrorMessage = "Name must be specified")]
[MaxLength(50, ErrorMessage = "Name too long, Name cannot contain more than 50 characters")]
public string Name {
get { return GetValue(() => Name); }
set { SetValue(() => Name, value); }
}
[Required(ErrorMessage = "Description must be specified")]
[MaxLength(150, ErrorMessage = "Description too long, Description cannot contain more than 150 characters")]
public string Description {
get { return GetValue(() => Description); }
set { SetValue(() => Description, value); }
}
}
错误模板:
<ControlTemplate x:Key="ValidationErrorTemplate">
<DockPanel LastChildFill="true">
<Border Background="Red" DockPanel.Dock="right"
Margin="-20,0,0,0" Width="10" Height="10" CornerRadius="10"
ToolTip="{Binding ElementName=customAdorner, Path=AdornedElement.(Validation.Errors)[0].ErrorContent}">
<TextBlock Text="!" VerticalAlignment="center" HorizontalAlignment="center" FontWeight="Bold" Foreground="white"/>
</Border>
<AdornedElementPlaceholder Name="customAdorner" VerticalAlignment="Center" >
<Border BorderBrush="red" BorderThickness="1" >
<Border.Effect>
<BlurEffect Radius="5" />
</Border.Effect>
</Border>
</AdornedElementPlaceholder>
</DockPanel>
</ControlTemplate>
数据模板/表格:
<DataTemplate x:Key="MyModelDetailsTemplate" DataType="{x:Type data:MyModel}" >
<StackPanel Grid.IsSharedSizeScope="True">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="auto" SharedSizeGroup="Labels" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Label Grid.Column="0">Name</Label>
<TextBox x:Name="Name"
Grid.Column="1"
MinWidth="150"
Validation.ErrorTemplate="{StaticResource ValidationErrorTemplate}"
Text="{Binding Name, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True, NotifyOnValidationError=True}" />
</Grid>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="auto" SharedSizeGroup="Labels" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Label Grid.Column="0">Description</Label>
<TextBox Grid.Column="1"
Validation.ErrorTemplate="{StaticResource ValidationErrorTemplate}"
Text="{Binding Description, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True, NotifyOnValidationError=True}" AcceptsReturn="True" VerticalAlignment="Stretch" />
</Grid>
</StackPanel>
</DataTemplate>
RelayCommand(完整性)
public class RelayCommand : ICommand
{
private Action<object> execute;
private Predicate<object> canExecute;
private event EventHandler CanExecuteChangedInternal;
public RelayCommand(Action<object> execute) : this(execute, DefaultCanExecute)
{
}
public RelayCommand(Action<object> execute, Predicate<object> canExecute)
{
if (execute == null)
{
throw new ArgumentNullException("execute");
}
if (canExecute == null)
{
throw new ArgumentNullException("canExecute");
}
this.execute = execute;
this.canExecute = canExecute;
}
public event EventHandler CanExecuteChanged {
add {
CommandManager.RequerySuggested += value;
this.CanExecuteChangedInternal += value;
}
remove {
CommandManager.RequerySuggested -= value;
this.CanExecuteChangedInternal -= value;
}
}
public bool CanExecute(object parameter)
{
return this.canExecute != null && this.canExecute(parameter);
}
public void Execute(object parameter)
{
this.execute(parameter);
}
public void OnCanExecuteChanged()
{
EventHandler handler = this.CanExecuteChangedInternal;
if (handler != null)
{
//DispatcherHelper.BeginInvokeOnUIThread(() => handler.Invoke(this, EventArgs.Empty));
handler.Invoke(this, EventArgs.Empty);
}
}
public void Destroy()
{
this.canExecute = _ => false;
this.execute = _ => { return; };
}
private static bool DefaultCanExecute(object parameter)
{
return true;
}
}
View 模型:
** 请注意，这里不需要 PropertyValidation，可以使用单独的 INotifyPropertyChanged 基础，我只将它用于 OnPropertyChanged 通知并保持简单 **
public class PageHomeVM : PropertyValidation
{
private ICommand saveCommand;
public ICommand SaveCommand {
get {
return saveCommand;
}
set {
saveCommand = value;
OnPropertyChanged();
}
}
public MyModel MyModel { get; set; } = new MyModel();
public PageHomeVM()
{
SaveCommand = new RelayCommand(SaveRecord, p => MyModel.IsValid);
MyModel.ClearValidation();
}
public void SaveRecord(object p)
{
//Perform the save....
}
}
查看:
<pages:BasePage.DataContext>
<ViewModels:PageHomeVM/>
</pages:BasePage.DataContext>
<StackPanel>
<Label Content="MyModel Details"/>
<ContentPresenter ContentTemplate="{StaticResource MyModelDetailsTemplate}" Content="{Binding MyModel}" />
<Button x:Name="btnSave"
Command="{Binding SaveCommand}"
Width="75"
HorizontalAlignment="Right">Save</Button>
</StackPanel>
我希望这有助于...
关于c# - 首次加载窗口时隐藏 WPF 验证错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/28463443/