Asp.net-mvc – Controller SessionStateBehavior is ReadOnly and I can update Session Variable

asp.netasp.net-mvcsession-variables

I expect that if controller has attribute SessionStateBehavior.ReadOnly then I can't change session variables inside this controller
but I can change values.

I try this code

 [SessionState(System.Web.SessionState.SessionStateBehavior.ReadOnly)]
    public class GLobalController : Controller
    {
      public  ActionResult Index()
        {
            Session["xxx"] = DateTime.Now.ToString();
            return View();
        }

Best Answer

see Writing to a read only session in MVC 3+

That post claims the behavior is inconsistent. I am definitely able to write to Session in Controllers using ReadOnly.

I Would treat it like this:

Required means you are requesting a exclusive lock on Session (i.e. no parallel processing of requests for the same sessionID)

ReadOnly means you are requesting a non-exclusive lock on Session (i.e. your request still has to wait for requests with an exclusive lock to finish, but you can process requests with non-exclusive locks in parallel. However it is up to you to ensure that your code doesn't write to Session. It's not necessarily enforced by the framework)

I realize this is counter to http://msdn.microsoft.com/en-us/library/system.web.sessionstate.sessionstatebehavior.aspx

Read-only session state is enabled for the request. This means that session state cannot be updated.

but it seems you in fact can update session state under some scenarios.

Related Solutions

Asp.net-mvc – Can an ASP.NET MVC controller return an Image

Use the base controllers File method.

public ActionResult Image(string id)
{
    var dir = Server.MapPath("/Images");
    var path = Path.Combine(dir, id + ".jpg"); //validate the path for security or use other means to generate the path.
    return base.File(path, "image/jpeg");
}

As a note, this seems to be fairly efficient. I did a test where I requested the image through the controller (http://localhost/MyController/Image/MyImage) and through the direct URL (http://localhost/Images/MyImage.jpg) and the results were:

MVC: 7.6 milliseconds per photo
Direct: 6.7 milliseconds per photo

Note: this is the average time of a request. The average was calculated by making thousands of requests on the local machine, so the totals should not include network latency or bandwidth issues.

Jquery – How to post an array of string to ASP.NET MVC Controller without a form

I modified my response to include the code for a test app I did.

Update: I have updated the jQuery to set the 'traditional' setting to true so this will work again (per @DustinDavis' answer).

First the javascript:

function test()
{
    var stringArray = new Array();
    stringArray[0] = "item1";
    stringArray[1] = "item2";
    stringArray[2] = "item3";
    var postData = { values: stringArray };

    $.ajax({
        type: "POST",
        url: "/Home/SaveList",
        data: postData,
        success: function(data){
            alert(data.Result);
        },
        dataType: "json",
        traditional: true
    });
}

And here's the code in my controller class:

public JsonResult SaveList(List<String> values)
{
    return Json(new { Result = String.Format("Fist item in list: '{0}'", values[0]) });
}

When I call that javascript function, I get an alert saying "First item in list: 'item1'". Hope this helps!

Best Answer

Related Solutions

Asp.net-mvc – Can an ASP.NET MVC controller return an Image

Jquery – How to post an array of string to ASP.NET MVC Controller without a form

Related Topic