使用Validation.HasError触发属性WPF时仅显示错误的样式

Question

I have a custom style for a text box that I only want to allow numerical values to be input.

I have created a custom ValidationRule to check for this.

If the input is valid I want to display a green border and if not I want to display a red border. The red border is displayed correctly when there is an error however the green is not displayed correctly when the input is correct, it just displays textbox defaults.

The ValidateResult method in my custom ValidationRule is:

 public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
    {            
        string input = (value ?? String.Empty).ToString();
        double val;
        if (double.TryParse(input, out val))
        {
            return new ValidationResult(true, OkMessage);
        }
        else return new ValidationResult(false, ErrorMessage);
    }

The Style and Triggers are defined:

<Style TargetType="{x:Type TextBox}">
        <Style.Triggers>
            <Trigger Property="Validation.HasError" Value="true">
                <Setter Property="Validation.ErrorTemplate">
                    <Setter.Value>
                        <ControlTemplate>                                
                                <Border BorderBrush="Red" BorderThickness="1"/>
                            </DockPanel>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Trigger>
            <Trigger Property="Validation.HasError" Value="False">
                <Setter Property="Validation.ErrorTemplate">
                    <Setter.Value>
                        <ControlTemplate>                                
                                <Border BorderBrush="Green" BorderThickness="1"/>
                            </DockPanel>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Trigger>
        </Style.Triggers>
    </Style>

How can I get the border to display green when the input is correctly validated?

Answer 1

I believe this is because Validation.HasError is cleared when there is no error, not set to false as your trigger requires. Why not just include the green border in your template? The HasError trigger will change it to red, but at all other times it should be green so best just to place that inline rather than a trigger.

Answer 2

The reason is you are setting ErrorTemplate which will he shown when there is an error...

you are changing error template color to green but error template will not be visible when there is no error...