Httphandler to retrive data and return it in JSON format

using System.Web.Script.Serialization;

///

/// Created by Wilmer F. Pascual

///

public class getdata : IHttpHandler

{

const string JSON_ARRAY = "[{0}]";

const string JSON_RECORD = "{{0}}";

const string JSON_KEYVALUE = "\"{0}\":\"{1}}\"";

const string COMMA = ",";

///

/// Retrieve Subcategories for the specified Category

///

///

void GetSubCategories(HttpContext context)

{

int parentCategoryId = int.Parse(context.Request.QueryString[Classes.Constants.QS_CATID]);

IEnumerable subCats = Classes.SubCategory.GetAll(parentCategoryId);

JavaScriptSerializer jSer = new JavaScriptSerializer();

string jsonData = jSer.Serialize(subCats);

context.Response.ContentType = "application/json";

context.Response.ContentEncoding = Encoding.UTF8;

context.Response.Write(jsonData);

context.Response.End();

}

public void ProcessRequest(HttpContext context)

{

if (context.Request.QueryString[Classes.Constants.QS_CATID] != null)

{

GetSubCategories(context);

}

}

public bool IsReusable

{

get

{

return false;

}

}

}

....

the data return can then be used by jquery (ex. used in cascading dropdown list Category -> Subcategories)

$(document).ready(function()

{

$("#").change(function()

{

$("#").html("");

$("#").attr("disabled", "disabled");

$("#").append($("").val('').html('loading...'));

var catId = $("#").attr("value");

if(isNaN(catId)) return;

$.getJSON('http://?catid=' + catId, function(sucats)

{

$("#").html("");

$.each(sucats, function() {

$("#").append($("").val(this['CategoryId']).html(this['CategoryName']));

});

});

$("#").attr("disabled", "");

})

});

Httphandler to retrive data and return it in JSON format