WPF / XAML - 当单选按钮被选中时，使用DataTriggers设置ValidatesOnDataErrors = false / true

Question

WPF / XAML - 当单选按钮被选中时，使用DataTriggers设置ValidatesOnDataErrors = false / true

3

我正在开发一个实现MVVM设计模式和DataAnnotations的应用程序。该应用程序是一个动态生成的页面列表。在这些页面中的一个页面上，我有10个必填字段和2个是/否单选按钮。这10个字段被分为两组，并且每个组都用边框标签包装起来。每个边框的可见性都与隐藏/可见的单选按钮绑定。

我的问题是如果选择了“是”，并显示了相关的5个必填文本框，如何将ValidatesOnDataErrors设置为false/true，并清除其他隐藏的必填文本框的文本框值?

下面是一段代码片段。

谢谢

<Border>
<Border.Style>
  <Style>
   <Setter Property="Border.Visibility" Value="Hidden"></Setter>
    <Style.Triggers>
     <DataTrigger Binding="{Binding ElementName=PresentlyEmployed_yes, Path=IsChecked}"
                  Value="True">
       <Setter Property="Border.Visibility" Value="Visible"></Setter>
     </DataTrigger>
    </Style.Triggers>
   </Style>
  </Border.Style>
  <Grid Height="Auto" Width="Auto">
   <Label Name="JobTitle"
               Content="{x:Static properties:Resources.JobTitlelbl}" />
    <TextBox Name="JobTitle" Text="{Binding JobTitle, Mode=TwoWay, 
     ValidatesOnDataErrors=True, UpdateSourceTrigger=PropertyChanged}">
     <TextBox.Style>
      <Style TargetType="{x:Type TextBox}">
       <Setter Property="Text" Value="{Binding PrimaryInsuredBusinessDuties, Mode=TwoWay,
          UpdateSourceTrigger=PropertyChanged, IsAsync=True}" />
       <Style.Triggers>
       <DataTrigger Binding="{Binding ElementName=PresentlyEmployed_yes, Path=IsChecked}"
          Value="True">
        <Setter Property="Text" Value="{Binding JobTitle, Mode=TwoWay, 
           ValidatesOnDataErrors=True, UpdateSourceTrigger=PropertyChanged}" />
       </DataTrigger>
       <DataTrigger Binding="{Binding ElementName=PresentlyEmployed_yes, Path=IsChecked}"
         Value="False">
        <Setter Property="Text" Value="{Binding JobTitle, Mode=TwoWay, 
          ValidatesOnDataErrors=False, UpdateSourceTrigger=PropertyChanged}"></Setter>
       </DataTrigger>
      </Style.Triggers>
     </Style>
    </TextBox.Style>
   </TextBox>
  </Grid>
</Border>

- Bobby

为什么不在触发器中重新绑定“Text”值，而不使用“ValidatesOnDataErrors”？ - Rachel

我尝试过了，但没起作用。问题在于一旦将ValidatesOnDataErrors设置为True，我尝试使用ValidatesOnDataErrors = False进行重新绑定，或者不包括ValidatesOnDataErrors，甚至如果我不将其绑定到任何内容，都无法删除验证。以下是我的属性外观：[Required(ErrorMessage = "必填字段！")] public string JobTitle { get { return _jobTitle; } set { _jobTitle = value; } }谢谢。 - Bobby

也许它没有更新UI是因为BindingSource没有改变。尝试在ViewModel中当RadioButton改变时触发PropertyChanged事件，除了重新绑定属性。 - Rachel

谢谢您的快速回复，让我试一下，稍后会再联系您。 - Bobby

还是没有运气！它把验证开启了，但却无法关闭。顺便说一下，在我的单选按钮属性设置器中，我会引发onpropertychanged事件并传递属性名称。我在每个属性设置器中都这样做。我有什么遗漏的吗？ - Bobby

2个回答

0

Sure, here is how my validationbase class looks like (Simplified)

    public class ValidationViewModelBase : ViewModelBase, IDataErrorInfo,   IValidationExceptionHandler
    {
    private Dictionary<string, Func<ValidationViewModelBase, object>> _propertyGetters;
    private Dictionary<string, ValidationAttribute[]> _validators;

    /// <summary>
    /// Gets the error message for the property with the given name.
    /// </summary>
    /// <param name="propertyName">Name of the property</param>
    public string this[string propertyName]
    {
         IList<string> fieldsNames = new List<string>();
    {
    if (propertyName == "PresentlyEmployed")
      {
        //if its true then
        fieldsNames.Add("JobTitle");

        AddFieldsValidation(fieldsNames); 
        }else{

        fieldsNames.Add("EmploymentAddress");

        RemoveValidation(fieldsNames); 
    }

  if (this.propertyGetters.ContainsKey(propertyName))
      {
            var propertyValue = this.propertyGetters[propertyName](this);
        var errorMessages = this.validators[propertyName]
                        .Where(v => !v.IsValid(propertyValue))
                        .Select(v => v.ErrorMessage).ToArray();
        return string.Join(Environment.NewLine, errorMessages);
      }
    return string.Empty;
    }

    /// <summary>
    /// Gets an error message indicating what is wrong with this object.
    /// </summary>
    public string Error
    {
        get
        {
        var errors = from validator in this.validators
                        from attribute in validator.Value
            where !attribute.IsValid(this.propertyGetters[validator.Key](this))
            select attribute.ErrorMessage;

            return string.Join(Environment.NewLine, errors.ToArray());
            }
        }

    }

    /// <summary>
    /// Gets the number of properties which have a validation attribute and are  currently valid
    /// </summary>
    public int ValidPropertiesCount
    {
        get
        {
            var query = from validator in this.validators
                where validator.Value.All(attribute => attribute.IsValid(this.propertyGetters[validator.Key](this)))
                select validator;

            var count = query.Count() - this.validationExceptionCount;
            return count;
            }
        }
}

/// <summary>
    /// Gets the number of properties which have a validation attribute
    /// </summary>
    public int TotalPropertiesWithValidationCount
    {
        get
        {
            return this.validators.Count();
        }
    }

public ValidationViewModelBase()
    {
        this.validators = this.GetType()
            .GetProperties()
            .Where(p => this.GetValidations(p).Length != 0)
            .ToDictionary(p => p.Name, p => this.GetValidations(p));

        this.propertyGetters = this.GetType()
            .GetProperties()
            .Where(p => this.GetValidations(p).Length != 0)
            .ToDictionary(p => p.Name, p => this.GetValueGetter(p));
    }

private ValidationAttribute[] GetValidations(PropertyInfo property)
    {
        return (ValidationAttribute[])property.GetCustomAttributes(typeof(ValidationAttribute), true);
    }

    private Func<ValidationViewModelBase, object> GetValueGetter(PropertyInfo property)
    {
        return new Func<ValidationViewModelBase, object>(viewmodel => property.GetValue(viewmodel, null));
    }

    private int validationExceptionCount;

    public void ValidationExceptionsChanged(int count)
    {
        this.validationExceptionCount = count;
        this.OnPropertyChanged("ValidPropertiesCount");
    }

- Bobby

@Rachel：上面的代码目前正在发挥作用。但是，我对添加或删除字段的方式并不感到自豪。因此，我想也许可以使用DataTriggers来完成这项工作。如果你有不同的方法，请告诉我。谢谢 - Bobby

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- Rachel · Accepted Answer

如果不想显示验证错误，可以尝试将Validation.Template设为{x:Null}

<StackPanel>
    <ListBox x:Name="MyListBox" SelectedIndex="0">
        <ListBoxItem>Validate Value 1</ListBoxItem>
        <ListBoxItem>Validate Value 2</ListBoxItem>
    </ListBox>

    <TextBox Text="{Binding Value1, ValidatesOnDataErrors=True}">
        <TextBox.Style>
            <Style TargetType="{x:Type TextBox}">
                <Style.Triggers>
                    <DataTrigger Binding="{Binding SelectedIndex, ElementName=MyListBox}" Value="1" >
                        <Setter Property="Validation.ErrorTemplate" Value="{x:Null}" />
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </TextBox.Style>
    </TextBox>
    <TextBox Text="{Binding Value2, ValidatesOnDataErrors=True}">
        <TextBox.Style>
            <Style TargetType="{x:Type TextBox}">
                <Style.Triggers>
                    <DataTrigger Binding="{Binding SelectedIndex, ElementName=MyListBox}" Value="0" >
                        <Setter Property="Validation.ErrorTemplate" Value="{x:Null}" />
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </TextBox.Style>
    </TextBox>
</StackPanel>