WPF: Display a bool value as “Yes” / “No”

问题:

I have a bool value that I need to display as "Yes" or "No" in a TextBlock. I am trying to do this with a StringFormat, but my StringFormat is ignored and the TextBlock displays "True" or "False".

<TextBlock Text="{Binding Path=MyBoolValue, StringFormat='{}{0:Yes;;No}'}" />

Is there something wrong with my syntax, or is this type of StringFormat not supported?

I know I can use a ValueConverter to accomplish this, but the StringFormat solution seems more elegant (if it worked).

回答1:

Your solution with StringFormat can't work, because it's not a valid format string.

I wrote a markup extension that would do what you want. You can use it like that :

<TextBlock Text="{my:SwitchBinding MyBoolValue, Yes, No}" />

Here the code for the markup extension :

public class SwitchBindingExtension : Binding
{
    public SwitchBindingExtension()
    {
        Initialize();
    }

    public SwitchBindingExtension(string path)
        : base(path)
    {
        Initialize();
    }

    public SwitchBindingExtension(string path, object valueIfTrue, object valueIfFalse)
        : base(path)
    {
        Initialize();
        this.ValueIfTrue = valueIfTrue;
        this.ValueIfFalse = valueIfFalse;
    }

    private void Initialize()
    {
        this.ValueIfTrue = Binding.DoNothing;
        this.ValueIfFalse = Binding.DoNothing;
        this.Converter = new SwitchConverter(this);
    }

    [ConstructorArgument("valueIfTrue")]
    public object ValueIfTrue { get; set; }

    [ConstructorArgument("valueIfFalse")]
    public object ValueIfFalse { get; set; }

    private class SwitchConverter : IValueConverter
    {
        public SwitchConverter(SwitchBindingExtension switchExtension)
        {
            _switch = switchExtension;
        }

        private SwitchBindingExtension _switch;

        #region IValueConverter Members

        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            try
            {
                bool b = System.Convert.ToBoolean(value);
                return b ? _switch.ValueIfTrue : _switch.ValueIfFalse;
            }
            catch
            {
                return DependencyProperty.UnsetValue;
            }
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            return Binding.DoNothing;
        }

        #endregion
    }

}

回答2:

You can also use this great value converter

Then you declare in XAML something like this:

<local:BoolToStringConverter x:Key="BooleanToStringConverter" FalseValue="No" TrueValue="Yes" />

And you can use it like this:

<TextBlock Text="{Binding Path=MyBoolValue, Converter={StaticResource BooleanToStringConverter}}" />

回答3:

Without converter

            <TextBlock.Style>
                <Style TargetType="{x:Type TextBlock}">
                    <Setter Property="Text" Value="OFF" />
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding MyBoolValue}" Value="True">
                            <Setter Property="Text" Value="ON" />
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </TextBlock.Style>

回答4:

There is also another really great option. Check this one : Alex141 CalcBinding.

In my DataGrid, I only have :

<DataGridTextColumn Header="Mobile?" Binding="{conv:Binding (IsMobile?\'Yes\':\'No\')}" />

To use it, you only have to add the CalcBinding via GitHub, than in the UserControl/Windows declaration, you add

<Windows XXXXX xmlns:conv="clr-namespace:CalcBinding;assembly=CalcBinding"/>

回答5:

This is a solution using a Converter and the ConverterParameter which allows you to easily define different strings for different Bindings:

public class BoolToStringConverter : IValueConverter
{
    public char Separator { get; set; } = ';';

    public object Convert(object value, Type targetType, object parameter,
                          CultureInfo culture)
    {
        var strings = ((string)parameter).Split(Separator);
        var trueString = strings[0];
        var falseString = strings[1];

        var boolValue = (bool)value;
        if (boolValue == true)
        {
            return trueString;
        }
        else
        {
            return falseString;
        }
    }

    public object ConvertBack(object value, Type targetType, object parameter,
                              CultureInfo culture)
    {
        var strings = ((string)parameter).Split(Separator);
        var trueString = strings[0];
        var falseString = strings[1];

        var stringValue = (string)value;
        if (stringValue == trueString)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

Define the Converter like this:

<local:BoolToStringConverter x:Key="BoolToStringConverter" />

And use it like this:

<TextBlock Text="{Binding MyBoolValue, Converter={StaticResource BoolToStringConverter},
                                       ConverterParameter='Yes;No'}" />

If you need a different separator than ; (for example .), define the Converter like this instead:

<local:BoolToStringConverter x:Key="BoolToStringConverter" Separator="." />

回答6:

This is another alternative simplified converter with "hard-coded" Yes/No values

[ValueConversion(typeof (bool), typeof (bool))]
public class YesNoBoolConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var boolValue = value is bool && (bool) value;

        return boolValue ? "Yes" : "No";
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return value != null && value.ToString() == "Yes";
    }
}

XAML Usage

<DataGridTextColumn Header="Is Listed?" Binding="{Binding Path=IsListed, Mode=TwoWay, Converter={StaticResource YesNoBoolConverter}}" Width="110" IsReadOnly="True" TextElement.FontSize="12" />

回答7:

The following worked for me inside a datagridtextcolumn: I added another property to my class that returned a string depending on the value of MyBool. Note that in my case the datagrid was bound to a CollectionViewSource of MyClass objects.

C#:

public class MyClass        
{     
    public bool MyBool {get; set;}   

    public string BoolString    
    {    
        get { return MyBool == true ? "Yes" : "No"; }    
    }    
}           

XAML:

<DataGridTextColumn Header="Status" Binding="{Binding BoolString}">