My problem is similar to the one here but doesn't involve PrimeFaces in any way. Also, I couldn't find a real solution there.
I'm basically trying to get the phaselistener to redirect to login page in case there is no JSF session (When, for example, session has timed out)
I'm trying to redirect from within a JSF 2 Phaselistener. To sum up, what I'm doing is this:
public void beforePhase(PhaseEvent event) {
PhaseId id = event.getPhaseId();
if(id.equals(PhaseId.RESTORE_VIEW)){
FacesContext context = event.getFacesContext();
Map<String, Object> sessionMap = context.getExternalContext().getSessionMap();
if(sessionMap==null || sessionMap.isEmpty()){
// No Session, Redirect to login
try {
context.getExternalContext().redirect("/login");
} catch (Exception e) {
...
}
}
}
}
When the redirect code runs I get this exception:
java.lang.NullPointerException
at org.apache.myfaces.context.servlet.PartialViewContextImpl.getPartialResponseWriter(PartialViewContextImpl.java:301)
at org.apache.myfaces.context.servlet.ServletExternalContextImpl.redirect(ServletExternalContextImpl.java:452)
at com.AuthenticationPhaseListener.userIsNotLogedIn
What could be causing this? Am I doing this wrong?
Thanks!
This seem to be happening during an ajax request. I'm not sure about the exact cause, the stacktrace at least indicates a possible bug in MyFaces implementation.
At least, the overall design approach is poor. This kind of HTTP request/response modifications should preferably not take place in a PhaseListener. There it is not intended for. You want to do this kind of job in a normal servlet Filter instead.
Well I had the same problem like you but I did not solve in in such a complicated way as you are doing.My steps
1) create a class that implements the PhaseListener
import javax.faces.application.NavigationHandler;
import javax.faces.context.FacesContext;
import javax.faces.event.PhaseEvent;
import javax.faces.event.PhaseId;
import javax.faces.event.PhaseListener;
/**
*
* #author fakumawah #date 09.03.2012
*/
public class LoggedInCheck extends BackingBean implements PhaseListener
{
#Override`enter code here`
public PhaseId getPhaseId()
{
return PhaseId.ANY_PHASE;
}
#Override
public void beforePhase(PhaseEvent event)
{
}
#Override
public void afterPhase(PhaseEvent event)
{
FacesContext fc = event.getFacesContext();
boolean loginPage = fc.getViewRoot().getViewId().lastIndexOf("login") > -1 ? true : false;
if (!loginPage && !loggedIn())
{
NavigationHandler nh = fc.getApplication().getNavigationHandler();
nh.handleNavigation(fc, null, "gotologin");
}
}
private boolean loggedIn()
{
return getSessionWrapper().isLoggedInAgain();
}
}
Sorry for the uncommented code but I guess the code is really easy to understand. Most important thing to note is the afterPhase(..) which checks if I am in the logged in or if I have a session already. If I don´t it creates a navigator and navigates me to the login page
2) Your isLoggedInAgain() should look something like this:
/**
* A method to check if Username is already logged in
* #param username
* #return
*/
public boolean isLoggedInAgain()
{
if (session != null) // Check if session is not null
{
if (session.isConnected()) // Check if session is connected
{
return true;
//destroyIfsLibrarySession(); // Session is available -> destroy session
}
else // session is not available
{
logger.log(Level.SEVERE, "Already logged out");
return false;
}
}
return false;
}
Since I am dealing with LibrarySessions from Oracle CMSDK that is why my test for the session looks like this. Most important is to check your session somehow and give out true or false, depending on if session exist or not.
3) Configure the Listener in faces-config.xml
<!-- Phase-Listener to check if user is logged in or not -->
<lifecycle>
<phase-listener>com.mycompany.mypackagename.webapp.LoggedInCheck</phase-listener>
</lifecycle>
4) Lastly define a navigation rule for the "gotologin"
<!-- Navigation Rule for sending user to login page from an expired session -->
<navigation-rule>
<from-view-id>*</from-view-id>
<navigation-case>
<from-outcome>gotologin</from-outcome>
<to-view-id>/login.em</to-view-id>
<redirect />
</navigation-case>
</navigation-rule>
And that is it, whenever you do not have a session on any page and are not on the login page, you will be carried to the login page.
Enjoy
Related
I'm trying to implement a web application using ASP.NET MVC and the Microsoft Unity DI framework. The application needs to support multiple user sessions at the same time, each of them with their own connection to a separate database (but all users using the same DbContext; the database schemas are identical, it's just the data that is different).
Upon a user's log-in, I register the necessary type mappings to the application's Unity container, using a session-based lifetime manager that I found in another question here.
My container is initialized like this:
// Global.asax.cs
public static UnityContainer CurrentUnityContainer { get; set; }
protected void Application_Start()
{
// ...other code...
CurrentUnityContainer = UnityConfig.Initialize();
// misc services - nothing data access related, apart from the fact that they all depend on IRepository<ClientContext>
UnityConfig.RegisterComponents(CurrentUnityContainer);
}
// UnityConfig.cs
public static UnityContainer Initialize()
{
UnityContainer container = new UnityContainer();
DependencyResolver.SetResolver(new UnityDependencyResolver(container));
GlobalConfiguration.Configuration.DependencyResolver = new Unity.WebApi.UnityDependencyResolver(container);
return container;
}
This is the code that's called upon logging in:
// UserController.cs
UnityConfig.RegisterUserDataAccess(MvcApplication.CurrentUnityContainer, UserData.Get(model.AzureUID).CurrentDatabase);
// UnityConfig.cs
public static void RegisterUserDataAccess(IUnityContainer container, string databaseName)
{
container.AddExtension(new DataAccessDependencies(databaseName));
}
// DataAccessDependencies.cs
public class DataAccessDependencies : UnityContainerExtension
{
private readonly string _databaseName;
public DataAccessDependencies(string databaseName)
{
_databaseName = databaseName;
}
protected override void Initialize()
{
IConfigurationBuilder configurationBuilder = Container.Resolve<IConfigurationBuilder>();
Container.RegisterType<ClientContext>(new SessionLifetimeManager(), new InjectionConstructor(configurationBuilder.GetConnectionString(_databaseName)));
Container.RegisterType<IRepository<ClientContext>, RepositoryService<ClientContext>>(new SessionLifetimeManager());
}
}
// SessionLifetimeManager.cs
public class SessionLifetimeManager : LifetimeManager
{
private readonly string _key = Guid.NewGuid().ToString();
public override void RemoveValue(ILifetimeContainer container = null)
{
HttpContext.Current.Session.Remove(_key);
}
public override void SetValue(object newValue, ILifetimeContainer container = null)
{
HttpContext.Current.Session[_key] = newValue;
}
public override object GetValue(ILifetimeContainer container = null)
{
return HttpContext.Current.Session[_key];
}
protected override LifetimeManager OnCreateLifetimeManager()
{
return new SessionLifetimeManager();
}
}
This works fine as long as only one user is logged in at a time. The data is fetched properly, the dashboards work as expected, and everything's just peachy keen.
Then, as soon as a second user logs in, disaster strikes.
The last user to have prompted a call to RegisterUserDataAccess seems to always have "priority"; their data is displayed on the dashboard, and nothing else. Whether this is initiated by a log-in, or through a database access selection in my web application that calls the same method to re-route the user's connection to another database they have permission to access, the last one to draw always imposes their data on all other users of the web application. If I understand correctly, this is a problem the SessionLifetimeManager was supposed to solve - unfortunately, I really can't seem to get it to work.
I sincerely doubt that a simple and common use-case like this - multiple users logged into an MVC application who each are supposed to access their own, separate data - is beyond the abilities of Unity, so obviously, I must be doing something very wrong here. Having spent most of my day searching through depths of the internet I wasn't even sure truly existed, I must, unfortunately, now realize that I am at a total and utter loss here.
Has anyone dealt with this issue before? Has anyone dealt with this use-case before, and if yes, can anyone tell me how to change my approach to make this a little less headache-inducing? I am utterly desperate at this point and am considering rewriting my entire data access methodology just to make it work - not the healthiest mindset for clean and maintainable code.
Many thanks.
the issue seems to originate from your registration call, when registering the same type multiple times with unity, the last registration call wins, in this case, that will be data access object for whoever user logs-in last. Unity will take that as the default registration, and will create instances that have the connection to that user's database.
The SessionLifetimeManager is there to make sure you get only one instance of the objects you resolve under one session.
One option to solve this is to use named registration syntax to register the data-access types under a key that maps to the logged-in user (could be the database name), and on the resolve side, retrieve this user key, and use it resolve the corresponding data access implementation for the user
Thank you, Mohammed. Your answer has put me on the right track - I ended up finally solving this using a RepositoryFactory which is instantiated in an InjectionFactory during registration and returns a repository that always wraps around a ClientContext pointing to the currently logged on user's currently selected database.
// DataAccessDependencies.cs
protected override void Initialize()
{
IConfigurationBuilder configurationBuilder = Container.Resolve<IConfigurationBuilder>();
Container.RegisterType<IRepository<ClientContext>>(new InjectionFactory(c => {
ClientRepositoryFactory repositoryFactory = new ClientRepositoryFactory(configurationBuilder);
return repositoryFactory.GetRepository();
}));
}
// ClientRepositoryFactory.cs
public class ClientRepositoryFactory : IRepositoryFactory<RepositoryService<ClientContext>>
{
private readonly IConfigurationBuilder _configurationBuilder;
public ClientRepositoryFactory(IConfigurationBuilder configurationBuilder)
{
_configurationBuilder = configurationBuilder;
}
public RepositoryService<ClientContext> GetRepository()
{
var connectionString = _configurationBuilder.GetConnectionString(UserData.Current.CurrentPermission);
ClientContext ctx = new ClientContext(connectionString);
RepositoryService<ClientContext> repository = new RepositoryService<ClientContext>(ctx);
return repository;
}
}
// UserData.cs (multiton-singleton-hybrid)
public static UserData Current
{
get
{
var currentAADUID = (string)(HttpContext.Current.Session["currentAADUID"]);
return Get(currentAADUID);
}
}
public static UserData Get(string AADUID)
{
UserData instance;
lock(_instances)
{
if(!_instances.TryGetValue(AADUID, out instance))
{
throw new UserDataNotInitializedException();
}
}
return instance;
}
public static UserData Current
{
get
{
var currentAADUID = (string)(HttpContext.Current.Session["currentAADUID"]);
return Get(currentAADUID);
}
}
public static UserData Get(string AADUID)
{
UserData instance;
lock(_instances)
{
if(!_instances.TryGetValue(AADUID, out instance))
{
throw new UserDataNotInitializedException();
}
}
return instance;
}
This is my controller code:
private string testVal;
public ActionResult Index()
{
testVal = "test";
return View();
}
public ActionResult NextView()
{
if (testVal == null)
Debug.WriteLine("testVal is null");
return View();
}
Is it possible to remeber values like testVal after changing page? It seems that when redirecting it resets values (testVal in NextVal is null).
Edit:
I try to save values to session but Session is null. I am using SignalR and when user is connected to page i use static event from hub to inform controller that user has connected - but inside method that runs on that event Session is unfortunetly null.
My controller code:
public ActionResult Index()
{
LoadingHub.userConnected += new EventHandler<IdEventArgs>(UserConnected);
return View();
}
private void UserConnected(object sender, IdEventArgs e)
{
Debug.WriteLine("User Connected with Id: " + e.Id);
if (Session == null)
Debug.WriteLine("Session is null");
}
My signalr hub:
public class LoadingHub : Hub
{
public static event EventHandler<IdEventArgs> userConnected;
//Function informs server that user has connected
public void Connected()
{
Debug.WriteLine("Hub Connected Method");
var id = Context.ConnectionId;
userConnected(this, new IdEventArgs(id));
}
}
Every time that you make a request a new instance of the controller is created so using a private field you will not be able to retain the value of this variable.
The easiest way for you to retain it it is to use a session. (if you want to retain this value per user base)
for example in your code
public ActionResult Index()
{
System.Web.HttpContext.Current.Session["testVal"] = "test";
return View();
}
public ActionResult NextView()
{
if (System.Web.HttpContext.Current.Session["testVal"] == null)
Debug.WriteLine("testVal is null");
return View();
}
you can use cookie or cache to replace the variable.
when you redirect to a webpage ，the controller will be newed ,so you cannot get the right testVal .but the cookie is stored in broswer .so you can set it and get .
You may use session or Pass the data to the controller
Have you looked into ASP.NET server side state management click here.
These are basically different ways to remember a value on the server once a new page has been loaded.
So a few server side techniques you could use to remember testVal are Session State or Application State. However Session State is more suitable for your scenario as it is only specific to the user's current session whereas Application State stores data that can be shared between sessions and would therefore be more ideal for global variables.
You can read the link I provided to read more on the differences though.
I would also like to warn you (as some say to use cookies), the user can delete or disable or manipulate them on the browser so this isn't an ideal solution.
I have an mvc 3 app for which I'm implementing authorization using my own login view which checks if the users name and password are allowed and then sets a variable in the session to say that the user is loggged in. This kind of works but for one particular view it is behaving in a strange undesirable way. The said view contains a form which I use to input some data and upload a file. For some reason which I can't figure out, after this form is posted a new session is started and therefore the variable which remembered that the user was logged in is reset to false and subsequently the login page is displayed again.
I'm lost as to why the application is starting a new session at this point? I have not instructed it to do this. Can anyone recommend solutions to stop this behaviour and get it to keep the old session?
Thanks.
UPDATE - Some Code:
Note the session seems to be terminated immediately after the response to the posted Create form
CMS controller which uses a custom Autorize attribute called "RDAutorize" on all actions:
[RDAuthorize]
public class PhotoCMSController : Controller
{
public ActionResult Create()
{
/* Code omitted: set up a newPhoto object with default state */
/* Display view containing form to upload photo and set title etc. */
return View("../Views/PhotoCMS/Create", newPhoto);
}
[HttpPost]
public ContentResult Upload(int pPhotoId)
{
/* Code ommited: receive and store image file which was posted
via an iframe on the Create view */
string thumbnail = "<img src='/path/to/thumb.jpg' />";
return Content(thumbnail);
}
[HttpPost]
public ActionResult Create(string pPhotoTitle, string pCaption etc...)
{
/*Code omitted: receive the rest of the photo data and save
it along with a reference to the image file which was uploaded
previously via the Upload action above.*/
/* Display view showing list of all photo records created */
return View("../Views/PhotoCMS/Index", qAllPhotos.ToList<Photo>());
/* **Note: after this view is returned the Session_End() method fires in
the Global.asax.cs file i.e. this seems to be where the session is
being lost** */
}
}/*End of CMS Controller*/
Custom Authorize action filter:
public class RDAuthorize : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
Boolean authorized = Convert.ToBoolean(
HttpContext.Current.Session["UserIsAuthorized"]
);
if (!authorized) {
/* Not logged in so send user to the login page */
filterContext.HttpContext.Response.Redirect("/Login/Login");
}
}
public override void OnActionExecuted(ActionExecutedContext filterContext) {}
public override void OnResultExecuting(ResultExecutingContext filterContext) {}
public override void OnResultExecuted(ResultExecutedContext filterContext) {}
}/*End of Authorize Action Filter*/
Login controller:
public class LoginController : Controller
{
private PhotoDBContext _db = new PhotoDBContext();
public ActionResult Login()
{
string viewName = "";
Boolean authorized = Convert.ToBoolean(Session["UserIsAuthorized"]);
if (authorized)
{
viewName = "../Views/Index";
}
else
{
viewName = "../Views/Login/Login";
}
return View(viewName);
}
[HttpPost]
public ActionResult Login(string pUsername, string pPassword)
{
string viewName = "";
List<Photo> model = new List<Photo>();
var qUsers = from u in _db.Users
select u;
foreach (User user in qUsers.ToList<User>())
{
/* If authorized goto CMS pages */
if (pUsername == user.Username && pPassword == user.Password)
{
Session["UserIsAuthorized"] = true;
var qPhotos = from p in _db.Photos
where p.IsNew == false
select p;
model = qPhotos.ToList<Photo>();
viewName = "../Views/PhotoCMS/Index";
break;
}
}
return View(viewName, model);
}
}/* End of Login controller */
Turns out the whole ASP.Net application was restarting because as part of the photo upload I was storing the image file in a temporary folder and then deleting the directory after moving the file to a permanent location. Apparently its default behaviour for ASP.Net to restart if a directory within the web site is deleted. I found this post
which describes the problem and offers a solution whereby the following code is added to the Global.asax.cs file. Implementing this solution has fixed the problem. The fix is applied by calling FixAppDomainRestartWhenTouchingFiles() from the Application_Start() event:
protected void Application_Start()
{
FixAppDomainRestartWhenTouchingFiles();
}
private void FixAppDomainRestartWhenTouchingFiles()
{
if (GetCurrentTrustLevel() == AspNetHostingPermissionLevel.Unrestricted)
{
/*
From: http://www.aaronblake.co.uk/blog/2009/09/28/bug-fix-application-restarts-on-directory-delete-in-asp-net/
FIX disable AppDomain restart when deleting subdirectory
This code will turn off monitoring from the root website directory.
Monitoring of Bin, App_Themes and other folders will still be
operational, so updated DLLs will still auto deploy.
*/
PropertyInfo p = typeof(HttpRuntime).GetProperty(
"FileChangesMonitor", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);
object o = p.GetValue(null, null);
FieldInfo f = o.GetType().GetField(
"_dirMonSubdirs", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.IgnoreCase);
object monitor = f.GetValue(o);
MethodInfo m = monitor.GetType().GetMethod(
"StopMonitoring", BindingFlags.Instance | BindingFlags.NonPublic);
m.Invoke(monitor, new object[] { });
}
}
private AspNetHostingPermissionLevel GetCurrentTrustLevel()
{
foreach (AspNetHostingPermissionLevel trustLevel in
new AspNetHostingPermissionLevel[] {
AspNetHostingPermissionLevel.Unrestricted,
AspNetHostingPermissionLevel.High,
AspNetHostingPermissionLevel.Medium,
AspNetHostingPermissionLevel.Low,
AspNetHostingPermissionLevel.Minimal }
)
{
try
{
new AspNetHostingPermission(trustLevel).Demand();
}
catch (System.Security.SecurityException)
{
continue;
}
return trustLevel;
}
return AspNetHostingPermissionLevel.None;
}
Since sessions are associated with cookies, they are available for a specific domain.
It's a common mistake to ask for a session variable in the same application while the domain has changed (i.e. redirecting to a subdomain).
Does the controller action that you are posting the form contains any [Authorize] attribute. You need to post some code.
Verify a new session is really started every time. Check Trace output for the user's session id to ensure it realllly has changed.
Ensure the cookie getting sent over is actually getting set and sent over. (called ASPsessionIDSOMETHING ) and if that is being sent by the browser. Download the tool Fiddler to check the cookies easily (set cookie header coming from the server and the request cookies going back to the server from the browser. Make sure your browser is accepting the cookie and you dont say... have cookies turned off.
If your session id is changing at every request then your session isn't properly getting set the first time, set a break point on that code if you havent already.
You can log when the worker process resets - ensure that isn't the case. see http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/IIS/87892589-4eda-4003-b4ac-3879eac4bf48.mspx
I had the same problem. The problem only occured when a post request was send to the server and the session was not modified during that request. What I did as a workaround was, to write a custom filter which does nothing more than writing a key / value into the session on each request and added that filter to the GlobalFilter collection in the global.asax.
public class KeepSessionAlive : IActionFilter
{
public void OnActionExecuting(ActionExecutingContext filterContext)
{
if(filterContext.HttpContext.Session != null)
{
filterContext.HttpContext.Session["HeartBeat"] = DateTime.Now.ToShortDateString();
}
}
public void OnActionExecuted(ActionExecutedContext filterContext) { }
}
And in the global.asax:
protected override void AddCustomGlobalFilters(GlobalFilterCollection filters)
{
filters.Add(new KeepSessionAlive());
}
This might be not the best solution but it helped me in my case.
I'd like to validate a Spring 3 MVC form. When an element is invalid, I want to re-display the form with a validation message. This is pretty simple so far. The rub is, when the user hits refresh after an invalid submission, I don't want them to POST, I want them to GET. This means I need to do a redirect from the form POST (submission) to re-display the form with validation messages (the form is submitted via a POST).
I'm thinking the best way to do this is to use SessionAttributeStore.retrieveAttribute to test if the form is already in the user's session. If it is, use the store form, otherwise create a new form.
Does this sound right? Is there a better way to do this?
To solve this problem, I store the Errors object in the session after a redirect on a POST. Then, on a GET, I put it back in the model. There are some holes here, but it should work 99.999% of the time.
public class ErrorsRedirectInterceptor extends HandlerInterceptorAdapter {
private final static Logger log = Logger.getLogger(ErrorsRedirectInterceptor.class);
private final static String ERRORS_MAP_KEY = ErrorsRedirectInterceptor.class.getName()
+ "-errorsMapKey";
#Override
public void postHandle(HttpServletRequest request, HttpServletResponse response,
Object handler, ModelAndView mav)
throws Exception
{
if (mav == null) { return; }
if (request.getMethod().equalsIgnoreCase(HttpMethod.POST.toString())) {
// POST
if (log.isDebugEnabled()) { log.debug("Processing POST request"); }
if (SpringUtils.isRedirect(mav)) {
Map<String, Errors> sessionErrorsMap = new HashMap<String, Errors>();
// If there are any Errors in the model, store them in the session
for (Map.Entry<String, Object> entry : mav.getModel().entrySet()) {
Object obj = entry.getValue();
if (obj instanceof Errors) {
if (log.isDebugEnabled()) { log.debug("Adding errors to session errors map"); }
Errors errors = (Errors) obj;
sessionErrorsMap.put(entry.getKey(), errors);
}
}
if (!sessionErrorsMap.isEmpty()) {
request.getSession().setAttribute(ERRORS_MAP_KEY, sessionErrorsMap);
}
}
} else if (request.getMethod().equalsIgnoreCase(HttpMethod.GET.toString())) {
// GET
if (log.isDebugEnabled()) { log.debug("Processing GET request"); }
Map<String, Errors> sessionErrorsMap =
(Map<String, Errors>) request.getSession().getAttribute(ERRORS_MAP_KEY);
if (sessionErrorsMap != null) {
if (log.isDebugEnabled()) { log.debug("Adding all session errors to model"); }
mav.addAllObjects(sessionErrorsMap);
request.getSession().removeAttribute(ERRORS_MAP_KEY);
}
}
}
}
It's not clear from your question but it sounds like your GET and POST actions are mapped to the same handler. In that case you can do something like:
if ("POST".equalsIgnoreCase(request.getMethod())) {
// validate form
model.addAttribute(form);
return "redirect:/me.html";
}
model.addAttribute(new MyForm());
return "/me.html";
In the JSP check if there are any error on the form and display as needed.
Such approach is called PRG (POST/REdirect/GET) design pattern I explained it few days ago as one of the answers:
Spring MVC Simple Redirect Controller Example
Hope it helps :)
I am working on a project management web application. The user has a variety of ways to display a list of tasks. When viewing a list page, they click on task and are redirected to the task edit page.
Since they are coming from a variety of ways, I am just curious as to the best way to redirect the user back to the calling page. I have some ideas, but would like to get other developers input.
Would you store the calling url in session? as a cookie? I like the concept of using an object handle the redirection.
I would store the referring URL using the ViewState. Storing this outside the scope of the page (i.e. in the Session state or cookie) may cause problems if more than one browser window is open.
The example below validates that the page was called internally (i.e. not requested directly) and bounces back to the referring page after the user submits their response.
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (Request.UrlReferrer == null)
{
//Handle the case where the page is requested directly
throw new Exception("This page has been called without a referring page");
}
if (!IsPostBack)
{
ReturnUrl = Request.UrlReferrer.PathAndQuery;
}
}
public string ReturnUrl
{
get { return ViewState["returnUrl"].ToString(); }
set { ViewState["returnUrl"] = value; }
}
protected void btn_Click(object sender, EventArgs e)
{
//Do what you need to do to save the page
//...
//Go back to calling page
Response.Redirect(ReturnUrl, true);
}
}
This message my be tagged asp.net but I think it is a platform independent issue that pains all new web developers as they seek a 'clean' way to do this.
I think the two options in achieving this are:
A param in the url
A url stored in the session
I don't like the url method, it is a bit messy, and you have to remember to include the param in every relevent URL.
I'd just use an object with static methods for this. The object would wrap around the session item you use to store redirect URLS.
The methods would probably be as follows (all public static):
setRedirectUrl(string URL)
doRedirect(string defaultURL)
setRedirectUrl would be called in any action that produces links / forms which need to redirect to a given url. So say you had a projects view action that generates a list of projects, each with tasks that can be performed on them (e.g. delete, edit) you would call RedirectClass.setRedirectUrl("/project/view-all") in the code for this action.
Then lets say the user clicks delete, they need to be redirected to the view page after a delete action, so in the delete action you would call RedirectClass.setRedirectUrl("/project/view-all"). This method would look to see if the redirect variable was set in the session. If so redirect to that URL. If not, redirect to the default url (the string passed to the setRedirectUrl method).
I agree with "rmbarnes.myopenid.com" regarding this issue as being platform independent.
I would store the calling page URL in the QueryString or in a hidden field (for example in ViewState for ASP.NET). If you will store it outside of the page scope (such as Session, global variable - Application State and so on) then it will not be just overkill as Tom said but it will bring you trouble.
What kind of trouble? Trouble if the user has more than one tab (window) of that browser open. The tabs (or windows) of the same browser will probably share the same session and the redirection will not be the one expected and all the user will feel is that it is a bug.
My 2 eurocents..
I personally would store the required redirection info in an object and handle globally. I would avoid using a QueryString param or the like since they could try bouncing themselves back to a page they are not supposed to (possible security issue?). You could then create a static method to handle the redirection object, which could read the information and act accordingly. This encapsulates your redirection process within one page.
Using an object also means you can later extend it if required (such as adding return messages and other info).
For example (this is a 2 minute rough guideline BTW!):
public partial class _Default : System.Web.UI.Page
{
void Redirect(string url, string messsage)
{
RedirectionParams paras = new RedirectionParams(url, messsage);
RedirectionHandler(paras); // pass to some global method (or this could BE the global method)
}
protected void Button1_Click(object sender, EventArgs e)
{
Redirect("mypage.aspx", "you have been redirected");
}
}
public class RedirectionParams
{
private string _url;
public string URL
{
get { return _url; }
set { _url = value; }
}
private string _message;
public string Message
{
get { return _message; }
set { _message = value; }
}
public RedirectionParams(string url, string message)
{
this.URL = url;
this.Message = message;
}
}