Asp.net mvc 3 - JSON post & AOP

1. Ajax call Asp.net MVC action

function save() {
var data = { 'Name': $('#name').val(), 'Age': $('#age').val() };
$.ajax({
url: '/user/Detail', //'@Url.Action("Detail", "user")',
data: JSON.stringify(data),
type: 'POST',
contentType: 'application/json', //'application/json; charset=utf-8',
dataType: 'json',
success: function (result) {
//
}
});
}

public class UserController : Controller{
public ActionResult Detail(string Name, string Age){
User user  = new Usr();
user.Name = Name;
user.Age = Age;
return View("Detail", user);
}
}

summarization:
1. How to post JSON and get
1.1 client passed data type is "json",
must add ---> contentType: 'application/json; charset=UTF-8', dataType: 'json',
change the literal object to string using method: data: JSON.stringify(data),
1.2 MVC recieve the data with
public ActionResult Detail(string Name, string Age){ // each parameter match the passed json data's each parameter.
or
public ActionResult Detail(User user){ // auto ORM.
1.3 passd the data cannot be retrieved by Request.Form.

2. How to post data(application/x-www-form-urlencoded) and get
2.1 if the client doesn't specify contentType, by default, the content type is 'application/x-www-form-urlencoded; charset=UTF-8', the

server can get the data with following, but still cannot b retrieved by Request.Form.
StreamReader sr = new StreamReader(Request.InputStream, Request.ContentEncoding);
string m = sr.ReadToEnd();
2.2 How to post data JSON and get with filter. IActionFilter is the AOP implementation in Asp.net Mvc. In filter, get the parameter as

follow.
filterContext.Controller.ValueProvider.GetValue("Name").AttemptedValue;

[MyAttribute(Message="TestJson")]
public ActionResult Detail(){....}

public class MyAttribute : FilterAttribute, IActionFilter
{
public string Message { get; set; }
public void OnActionExecuting(ActionExecutingContext filterContext)   // before executing the method
{
filterContext.Controller.ValueProvider.GetValue("Name").AttemptedValue;

filterContext.HttpContext.Response.Write(
string.Format("[Before Action: {0}]", Message));
}
public void OnActionExecuted(ActionExecutedContext filterContext)  // after executed the method
{
filterContext.HttpContext.Response.Write(
string.Format("[After Action: {0}]", Message));
}
}

3. 1 Request.Form works in asp.net mvc, if the dataType is by default and data is '{a:'1', b:'2'}'.

$.ajax({
url: '/user/Detail',
data: {name: 'Tom'},     // have a test  by enclosing name with single quote if test failed.
type: 'POST',
success: function (result) {
alert(result);
},
error: function (xhRequest, text, thrownError) {
alert(xhRequest);
}
});