Question

I need to format boolean as string for multilanguage support "Ja"/"Nein". What is the right format string that I need for DisplayFormat and EditFormat?
I am using DevExpress with repositoryItemTextEdit as column editor in design but I think it’s the same with any other binding string format. Is there another approach?

Answer 1

You should definitely extract literal values “Ja”/”Nein” into localization resources. Laoujin makes a great response, but I will expand it a little bit with examples.

First, define custom format provider, that will use localization in some sort

public class LocalizedBoolFormatter : IFormatProvider, ICustomFormatter
{
    public string Format(string format, object arg, IFormatProvider formatProvider)
    {
        bool value = (bool)arg;
        format = (format == null ? null : format.Trim().ToLower());

        switch (format)
        {
            case "yn":
                return GetLocalizedBool(value);
            default:
                return HandleDefaultFormat(arg, format, formatProvider);
        }
    }

    public object GetFormat(Type formatType)
    {
        if (formatType == typeof(ICustomFormatter))
            return this;
        else
            return null;
    }
}

Private methods for LocalizedBoolFormatter could look like:

private string HandleDefaultFormat(object value, string format, IFormatProvider formatProvider)
{
    if (value is IFormattable)
        return ((IFormattable)value).ToString(format, formatProvider);
    else
        return value.ToString();
}

private string GetLocalizedBool(bool value)
{
    //extract from localization resources  
    //or use CultureInfo.CurrentCulture for poors man localization 
    return value ? "Ja" : "Nein";
}

Then you can simply format value using custom formater, which would be localized by a formatter

bool f = false;
string formatted = string.Format(new LocalizedBoolFormatter(), "{0:yn}", f);
Console.WriteLine (formatted);

With DevExpress RepositoryItemTextEdit you can use the Custom Formatting as follows:

repositoryItemTextEdit.DisplayFormat.Format = new LocalizedBoolFormatter();
repositoryItemTextEdit.DisplayFormat.FormatType = FormatType.Custom;