public ActionResult AssessmentOverTime(List<Foo> foos)
{
  LineGraphDTO model = new LineGraphDTO() {
      data = foos.Select(foo => new { value = foo.Value, date = foo.date.ToString("yyyy-MM-dd") }).ToList<object>(),
      element = "chart",
      labels = new List<string> { "Value" },
      xkey = "date",
      ykeys = new List<string> {"value"},
  };
  return View(model);
}

<script>
  new Morris.Line(@Html.Raw(Model.ToJSON()));
</script>