MVC-attribute to ensure certain route-value

EnsureRouteValueAttribute.cs

public class EnsureRouteValueAttribute : ActionFilterAttribute
{
    private readonly bool ignoreCase;

    private readonly string routeValueKey;

    private readonly string ensureRouteValue;

    public EnsureRouteValueAttribute(string routeValueKey, string ensureRouteValue, bool ignoreCase = true)
    {
        this.ignoreCase = ignoreCase;
        this.routeValueKey = routeValueKey;
        this.ensureRouteValue = ensureRouteValue;
    }

    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        object value;
        filterContext.RouteData.Values.TryGetValue(routeValueKey, out value);
        string routeValue = Convert.ToString(value);

        var comparison = ignoreCase ? StringComparison.OrdinalIgnoreCase : StringComparison.Ordinal;
        if (routeValue.Equals(ensureRouteValue, comparison))
        {
            return;
        }

        var routeValues = filterContext.RouteData.Values;
        routeValues[routeValueKey] = ensureRouteValue;
        filterContext.Result = new RedirectToRouteResult(routeValues);
    }
}