Question

I have a user reporting that when they use the back button to return to a web page that they come back as a different person. It seems like they may be accessing a different users profile.

Here are the important parts of the code:

//here's the code on the web page  public static WebProfile p = null;  protected void Page_Load(object sender, EventArgs e) {     p = ProfileController.GetWebProfile();     if (!this.IsPostBack)     {          PopulateForm();     }        }  //here's the code in the 'ProfileController' (probably misnamed) public static WebProfile GetWebProfile() {     //get shopperID from cookie     string mscsShopperID = GetShopperID();     string userName = new tpw.Shopper(Shopper.Columns.ShopperId,        mscsShopperID).Email;     p = WebProfile.GetProfile(userName);      return p; } 

I’m using static methods and a static WebProfile because I need to use the profile object in a static WebMethod (ajax pageMethod).

• Could this lead to the profile object being ‘shared’ by different users?
• Am I not using static methods and objects correctly?

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The reason I changed WebProfile object to a static object was because I need to access the profile object within a [WebMethod] (called from javascript on the page).

• Is there a way to access a profile object within a [WebMethod]?
• If not, what choices do I have?

Answer 1

A static object is shared across all instances of an application so if you alter the value of a static object, that alteration will be reflected across all instances of the application which access that object. Therefore if your web profile is reassigned by another thread (i.e. a second user visiting a page) inbetween you setting it for the current user, it will contain information different to what you expect.

To get around this your code should look something like:

public WebProfile p = null;  protected void Page_Load(object sender, EventArgs e) {     p = ProfileController.GetWebProfile();     if (!this.IsPostBack)     {          PopulateForm();     }        }  public static WebProfile GetWebProfile() {     //get shopperID from cookie     string mscsShopperID = GetShopperID();     string userName = new tpw.Shopper(Shopper.Columns.ShopperId,        mscsShopperID).Email;     return WebProfile.GetProfile(userName);  } 

Note that the static object has not been set and the returned value should be assigned to a NON STATIC instance of the web profile class in your calling method.

Another option is to LOCK your static variable for the whole time it is in use but this will lead to severe degradation in performance as the lock will block any other requests for the resource until the current locking thread is completed – not a good thing in a web app.