public DataSourceResult GetRateTks([ModelBinder(typeof(WebApiDataSourceRequestModelBinder))]DataSourceRequest request, string locs, string titles)
 {
    locs = locs ?? "";
    titles = titles ?? "";
    using (var ctx = new ModelerContext())
    {
       IEnumerable<RateTkVM> tks = ctx.getRateTks(locs, titles);
       return tks.ToDataSourceResult(request);
    }
 }