Question

I have a model which has some double properties on it, and with them come a DisplayFormat which converts the double into a nice readable percent.. example

[DisplayFormat(DataFormatString = "{0:P2}")]
public Nullable<double> Yearly_act_pct { get; set; }

This works fine in HTML partials where I wrap the call in

@Html.DisplayFor(modelItem => item.Yearly_act_pct)

However, when I dump some of these objects into a JSON feed, the DisplayFormats seem to be ignored, so I end up with raw decimals, and often big ones.

How can I make this

return Json(myObjects, JsonRequestBehavior.AllowGet);

respect the DisplayFormats?

Answer 1

The call to return Json(myObjects, JsonRequestBehavior.AllowGet) actually returns a JsonResult. The internals of the JsonResult perform a call:

JavaScriptSerializer serializer = new JavaScriptSerializer();
response.Write(serializer.Serialize(Data));

If you look at MSDN for JavascriptSerializer you will there is a simple conversion. This implementation does not appear to honor DisplayFormat.

You can write a class derived from JsonResult that honors the DisplayFormat attribute.