Returning JSON object from an ASP.NET page

Question

Hi,

In my particular situation, I have couple of solutions to my problem. I want to find out which one is more feasible. In this case, I can also achieve my goal by returning a JSON object from my server side code, however, I do not know how it is done and what is the best way of doing it.

First off, I don't need a full aspx page as I only need a response returned from code. So, do I use web services? handler? or is there any other specific way you people do this?

Is this solution feasible? do I build the JSON string using the StringBuilder class and inject that string into the target aspx page? are there any precautions? or things that I should be aware of?

I appreciate your ideas.

Regards,

Kemal

------------UPDATE !------------

Suppose I have a JSON object in my userlist.aspx page. which then I use it with jQuery...

{"menu": {
  "id": "color1",
  "value": "color",
  "popup": {
    "menuitem": [
      {"value": "Red"},
      {"value": "Green"},
      {"value": "Yellow"}
    ]
  }
}} // example taken from the json.org/example page

now when I want to add a new menuitem from my aspx page, what do I do... I think this way my question is more specific... Lets assume I create a new string in my aspx code, as such "{"value": "Blue"}. Now how do I inject this into the already existing itemlist in the target page? or is this not the correct approach to this kind of situation? if not how else can it be achieved? Also if I wanted to fire a jquery event when a new item is added to this list, how is this achieved?

Answer 1

no problem doing it with asp.... it's most natural to do so with MVC, but can be done with standard asp as well.

The MVC framework has all sorts of helper classes for JSON, if you can, I'd suggest sussing in some MVC-love, if not, you can probably easily just get the JSON helper classes used by MVC in and use them in the context of asp.net.

edit:

here's an example of how to return JSON data with MVC. This would be in your controller class. This is out of the box functionality with MVC--when you crate a new MVC project this stuff gets auto-created so it's nothing special. The only thing that I"m doing is returning an actionResult that is JSON. The JSON method I'm calling is a method on the Controller class. This is all very basic, default MVC stuff:

public ActionResult GetData()
{
    data = new { Name="kevin", Age=40 };
    return Json(data, JsonRequestBehavior.AllowGet);
}

This return data could be called via JQuery as an ajax call thusly:

$.get("/Reader/GetData/", function(data) { someJavacriptMethodOnData(data); });

Answer 2

In your Page_Load you will want to clear out the normal output and write your own, for example:

string json = "{\"name\":\"Joe\"}";
Response.Clear();
Response.ContentType = "application/json; charset=utf-8";
Response.Write(json);

To convert a C# object to JSON you can use a library such as Json.NET.

Instead of getting your .aspx page to output JSON though, consider using a Web Service (asmx) or WCF, both of which can output JSON.

Answer 3

here are quite a good solutions to my problem:

http://www.mikesdotnetting.com/Article/96/Handling-JSON-Arrays-returned-from-ASP.NET-Web-Services-with-jQuery

also be sure to read this: http://encosia.com/2009/02/10/a-breaking-change-between-versions-of-aspnet-ajax/