/// <summary>
/// Returns the value of this element, converted to type T. If the element does not exist returns the default
/// value. If the element's value cannot be converted, throws an exception.</summary>
public static T ValueOrDefault <T>(this XElement element, XName name, T defaultValue)
{
XElement el = element.Element(name);
if (el == null)
{
return(defaultValue);
}
else
{
try { return(ExactConvert.To <T>(el.Value)); }
catch (ExactConvertException E) { throw new InvalidOperationException(("Element \"{0}/{1}\", when present, must contain a value convertible to a certain type: " + E.Message).Fmt(element.Path(), name)); }
}
}
public static T GetValidated <T>(this HttpRequest request, string varName, T varDefault, Func <T, bool> validator, string mustBe)
{
var valueStr = request.Url[varName];
if (valueStr == null)
{
return(varDefault);
}
T value;
try { value = ExactConvert.To <T>(valueStr); }
catch (ExactConvertException) { throw new ValidationException(varName, valueStr, "convertible to {0}".Fmt(typeof(T))); }
if (!validator(value))
{
throw new ValidationException(varName, valueStr, mustBe);
}
return(value);
}