如果文本框無效，則不禁用按鈕

Question

我有經過驗證的電子郵件文本塊

<TextBox x:Name="email" Style="{StaticResource emaliStyle}" Grid.Column="2" Grid.Row="2">
                <TextBox.Text>
                    <Binding  Mode="TwoWay" Path="Email"  UpdateSourceTrigger="PropertyChanged">
                        <Binding.ValidationRules>
                            <DataErrorValidationRule ValidatesOnTargetUpdated="False"/>
                        </Binding.ValidationRules>
                    </Binding>
                </TextBox.Text>
            </TextBox>

 <Style TargetType="TextBox" x:Key="emaliStyle">
        <Setter Property="Width" Value="220"/>
        <Setter Property="Height" Value="30"/>
        <Setter Property="FontSize" Value="18"/>
        <Setter Property="HorizontalAlignment" Value="Left"/>
        <Setter Property="VerticalAlignment" Value="Center"/>
        <Setter Property="FontSize" Value="20"/>
        <Setter Property="Padding" Value="6,1,1,0"/>

        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type TextBox}">
                    <Border x:Name="border" BorderBrush="{TemplateBinding BorderBrush}" 
                            BorderThickness="{TemplateBinding BorderThickness}" 
                            Background="{TemplateBinding Background}" 
                            CornerRadius="10"
                            SnapsToDevicePixels="True">
                        <ScrollViewer x:Name="PART_ContentHost" Focusable="false" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden"/>
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsEnabled" Value="false">
                            <Setter Property="Opacity" TargetName="border" Value="0.56"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>

        <Setter x:Name="LoginValidation" Property="Validation.ErrorTemplate">
            <Setter.Value>
                <ControlTemplate>
                    <DockPanel LastChildFill="True">
                        <TextBlock DockPanel.Dock="Bottom" Foreground="Maroon" FontSize="8pt"
                                           Text="{Binding ElementName=email, Path=AdornedElement.(Validation.Errors)[0].ErrorContent}">
                        </TextBlock>
                        <AdornedElementPlaceholder Name="email" />
                    </DockPanel>
                </ControlTemplate>
            </Setter.Value>
        </Setter>

        <Style.Triggers>
            <Trigger Property="Validation.HasError" Value="True">
                <Setter Property="BorderBrush" Value="DarkRed" />
                <Setter Property="BorderThickness" Value="2" />
            </Trigger>
        </Style.Triggers>
    </Style>

驗證工作並向我展示我在 viewModel 中編寫的消息（沒關系）

如果字段無效，下一步它會阻止按鈕。

我的按鈕和樣式

 <Button x:Name="SignInButton" 
                    Style="{StaticResource SignInButton}"
                    Command="{Binding SignInCommand}" 
                    CommandParameter="{Binding ElementName=This}" 
                    Content="Sign In"/>

 <Style TargetType="Button" x:Key="SignInButton">
        <Setter Property="Background" Value="MidnightBlue"/>
        <Setter Property="Foreground" Value="White"/>
        <Setter Property="FontSize" Value="16"/>
        <Setter Property="FontWeight" Value="Bold"/>
        <Setter Property="Width" Value="100"/>
        <Setter Property="Height" Value="40"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type Button}">
                    <Border Background="{TemplateBinding Background}" CornerRadius="10">
                        <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" Height="20" Margin="26,10"/>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Setter Property="IsEnabled" Value="False"/>
        <Style.Triggers >
            <MultiDataTrigger>
                <MultiDataTrigger.Conditions>
                    <Condition Binding="{Binding Path=(Validation.HasError), ElementName=email}" Value="False"/>
                </MultiDataTrigger.Conditions>
                <Setter Property="IsEnabled" Value="True"/>
            </MultiDataTrigger>
            <Trigger Property="IsMouseOver" Value="True">
                <Setter Property="Background" Value="LimeGreen"/>
            </Trigger>

        </Style.Triggers>
    </Style>

我編寫了Multitrigger （稍后添加其他文本框字段）來禁用我的按鈕，但它不起作用。

我嘗試用元素名稱寫所有Email沒有幫助。 我想念什么？ 因為會顯示錯誤信息並且字段邊框標記為紅色，所以 bu 未禁用

Answer 1

每當您想禁用綁定到SignInCommand的Button ，您的BlockButton()方法都應返回false 。 綁定到命令時，沒有理由在樣式中設置IsEnabled屬性。

要刷新命令和Button的狀態，您應該在驗證狀態更改時引發命令的CanExecuteChanged事件。 大多數ICommand實現都包含RaiseCanExecuteChanged()方法或類似方法，可讓您執行此操作：

private bool _isEmailValid;

private bool BlockButton()
{
    return _isEmailValid && IsAppDeveloper == false && IsEndUser == false;
}

public string this[string columnName]
{
    get
    {
        string error = String.Empty;
        switch (columnName)
        {
            case "Email":
                string s = ValidateModelProperty(Email, columnName);
                _isEmailValid = string.IsNullOrEmpty(s);
                SignInCommand.RaiseCanExecuteChanged();
                return s;
        }

        return error;
    }
}

private string ValidateModelProperty(object value, string propertyName)
{
    ICollection<ValidationResult> validationResults = new List<ValidationResult>();
    ValidationContext validationContext = new ValidationContext(this, null, null) { MemberName = propertyName };
    if (!Validator.TryValidateProperty(value, validationContext, validationResults))
        foreach (ValidationResult validationResult in validationResults)
            return validationResult.ErrorMessage;
    return null;
}