Format as currency with no trailing zeroes in wpf xaml

Question

Assuming we have a viewmodel property MyMoney. How can I format it in its view xaml as a currency with no trailing zeroes?

For example:

MyMoney = 1; //$1
MyMoney = 1.2 //$1.2

I've tried the following in xaml (e.g. <TextBox Text="{Binding MyMoney, StringFormat=..."/>) but it doesn't satisfy all the conditions:

StringFormat=C shows currency but also trailing zeroes.
StringFormat=C0 shows currency but shows only the whole number.
StringFormat={}{0:0.##} does not show trailing zeroes but not as currency.
StringFormat={}{0:$0.##} does not show trailing zeroes but hard-coded $. We should be able to cater current locale/culture's currency.

Answer 1

First, I would like to give credit to @Andy for his answer which led me to use IValueConverter.

I'm posting my solution which offers the following benefits:

1. Leverage C#'s "C" format specifier

   a. Consider negative values (e.g. -1 --> ($1))

   b. Cater varying current locale/culture

2. Bind to multiple data types (decimal, double, int, etc).

3. Return DependencyProperty.UnsetValue when ConvertBack is unable to produce a value.

All of the above follow how StringFormat=c will behave in wpf (e.g. in a TextBox) except the converter removes trailing zeroes as desired.

---

public class CurrencyFormatConverter : MarkupExtension, IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) =>
        System.Convert.ToDecimal(value).ToCurrency(culture);

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        switch (Type.GetTypeCode(targetType))
        {
            case TypeCode.Decimal:
                return Decimal.TryParse(value.ToString(), NumberStyles.Currency, culture, out var @decimal)
                    ? @decimal
                    : DependencyProperty.UnsetValue;

            case TypeCode.Double:
                return Double.TryParse(value.ToString(), NumberStyles.Currency, culture, out var @double)
                    ? @double
                    : DependencyProperty.UnsetValue;

            case TypeCode.Int16:
                return Int16.TryParse(value.ToString(), NumberStyles.Currency, culture, out var int16)
                    ? int16
                    : DependencyProperty.UnsetValue;

            case TypeCode.Int32:
                return Int32.TryParse(value.ToString(), NumberStyles.Currency, culture, out var int32)
                    ? int32
                    : DependencyProperty.UnsetValue;

            case TypeCode.Int64:
                return Int64.TryParse(value.ToString(), NumberStyles.Currency, culture, out var int64)
                    ? int64
                    : DependencyProperty.UnsetValue;

            case TypeCode.Single:
                return Single.TryParse(value.ToString(), NumberStyles.Currency, culture, out var single)
                    ? single
                    : DependencyProperty.UnsetValue;

            case TypeCode.UInt16:
                return UInt16.TryParse(value.ToString(), NumberStyles.Currency, culture, out var uint16)
                    ? uint16
                    : DependencyProperty.UnsetValue;

            case TypeCode.UInt32:
                return UInt32.TryParse(value.ToString(), NumberStyles.Currency, culture, out var uint32)
                    ? uint32
                    : DependencyProperty.UnsetValue;

            case TypeCode.UInt64:
                return UInt64.TryParse(value.ToString(), NumberStyles.Currency, culture, out var uint64)
                    ? uint64
                    : DependencyProperty.UnsetValue;

            default:
                throw new NotSupportedException($"Converting currency string to target type {targetType} is not supported.");
        }
    }

    public override object ProvideValue(IServiceProvider serviceProvider) => this;
}

---

More info on ToCurrency here

public static class DecimalExtensions
{
    /// <summary>
    ///     Converts a numeric value to its equivalent currency string representation using the specified culture-specific format information.
    /// </summary>
    /// <param name="value">The value to be converted.</param>
    /// <param name="provider">An object that supplies culture-specific formatting information.</param>
    /// <returns>The currency string representation of the value as specified by <paramref name="provider" />.</returns>
    public static string ToCurrency(this decimal value, IFormatProvider provider) =>
        /// Use "1" (or "-1" if value is negative)
        /// as a placeholder for the actual value.
        (value < 0 ? -1 : 1)

        /// Format as a currency using the "C" format specifier.
        .ToString("C0", provider)

        /// Convert the absolute value to its string representation
        /// then replace the placeholder "1".
        /// We used absolute value since the negative sign
        /// is already converted to its string representation
        /// using the "C" format specifier.
        .Replace("1", Math.Abs(value).ToString("#,0.############################", provider));
}