I have a textbox where the user enters some data and saves this value to the database. Next time the user comes to the same aspx page in the same session, the value should be restored in the textbox. Whats the best way to do this? Using the session maybe?
Thanks :-)
The session is a good way to save the data. You also should have a way to load the data from the database if the session is not available. (ie, they come to the same page the next day)
something like this:
public string MyVariable
{
get
{
if (Session["MyVariable"] == null)
{
Session["MyVariable"] = LoadFromDatabase();
}
return Session["MyVariable"];
}
}
protected void Page_Load(object sender, EventArgs e)
{
MyTextBox.Text = MyVariable;
}
Using the session, you will be able to do it only within a session unless you maintain a session in state server or in database.
For the first time, store the user entered text into the session and also update it in the Database. Later, whenever you need to show this value to the user, check whether the textbox value exits in the session. If not, then read it from the database, update the session with the value and show it to the user.
Related
Let's say that in an ASP.NET .aspx page I have the Page Load method and another method for a button click event.
In the Page Load method I'm checking if the user is logged in by checking the Session. Whether he is or not, I'm storing the result in a Global Variable.
Boolean isGuest = false;
protected void Page_Load(object sender, EventArgs e) {
if(Session["id"]==null)
isGuest = true;
else
isGuest = false;
}
Let's say 20 minutes have passed, and I don't know if the Session has terminated or not, and then I click a Button, the event goes like this:
protected void Button_Click(object sender, EventArgs e) {
if(isGuest==false)
//do something
else
// do another thing
}
My Question is : When I'm clicking the button, does ASP.NET go through the Page_Load method again (check isGuest again) or it simply executes what's inside the Button_Click method, means, it uses a Boolean isGuest that could be false, but in reality the session is terminated, means it should be true.
Page_Load is triggered always before the control events.
Have a look: ASP.NET Page Life Cycle Overview
Side-note: If you want to do things only on the first load and not on every postback you have to check the IsPostBack property.
You can:
Define your own class with the UserID, and other profile properties;
Add that class to session in the global.asax session started event Session["NameReferingToYourClass"] = new YourClass();
Set a member variable to your session object early in the page life cycle mYourClass = Session["NameReferingToYourClass"] casted if you need to;
Then you can make any changes to your class anywhere in the code your member variable is available;
Save back your class with all the changes into session on the Page.Unload(..){ Session["NameReferingToYourClass"] = mYourClass.
This way you are using your class properties in your code, including UserId, pretty much like a windows application, there will be no mentioning of session anywhere else in your code.
In my application, I have a form that users fill out, then gets approved by a manager. I have various types of forms that all use the same process, so the approval buttons are all done via a user control (which includes the functionality to update the data in the database and call the postback).
However, once I click on the "Approve" button (which is in the user control), the form information doesn't update (it still says "unapproved"). A postback is definitely happening, but not sure why the page isn't updating properly.
I can confirm that the change are being made - when I manually reload the page, it gets updated - but not on the post back.
What am I missing here?
My page:
protected void Page_Load(object sender, EventArgs e)
{
int ID;
// ensure that there's an ID set in the query string
if (Int32.TryParse(Request.QueryString["ID"], out ID))
PopulatePage(ID);
else
Response.Redirect("~/Default.aspx");
}
}
protected void PopulatePage(int ID)
{
using (WOLinqClassesDataContext db = new WOLinqClassesDataContext())
{
lblStatus.Text = wo.Workorder.status;
....
}
}
I think that the Page_Load happens before the code in the submit button. To check this just use a couple of breakpoints. So the page loads the old data since the new data are not saved yet.
You should call a method to load the data inside the OnClick method of the Approve button.
After you've submitted the changes to the database, try running db.Refresh(RefreshMode.OverwriteCurrentValues) to force the changes to be reloaded into the data context.
I have a site with multiple pages, not necessarily heirarchical. I want to query the user's identity (using AD...) whenever the user first enters the site, and create session state variables for the convenience of other pages as needed. A user could possibly enter the site without going through the default.aspx page, so I thought I'd put the code in the Master Page's code-behind.
On the assumption this is a good idea, versus some sort of static class that maintains this information, I started setting it up, but found the Master Page code-behind doesn't always seem to get fired when I enter the site. Is this a debugging phenomenon, or am I right, and the Master Page is the wrong place to put this code...?
I would recommend using the Global.asax class. You'll need to add it to your web app if it's not already there. Once you have it, you can then use the various events (session start and end, app start and end and error) to implement business logic particular to what you need exactly.
I tend to monkey around with the logged in user in the Application_PreRequestHandlerExecute event of the global.asax. This will allow you to look at the User Principle (eg - User.Identity.Name) to see who is logged in (or if they're not logged in) and do what you need to (such as set Session information for the user, etc.).
Here's a tidbit of code I've got on one .NET web app that uses the Global.asax for storing user data in the Session.
protected void Application_PreRequestHandlerExecute(Object sender, EventArgs e) {
if (Context.Handler is IRequiresSessionState || Context.Handler is IReadOnlySessionState) {
SetUserItem();
}
}
private void SetUserItem() {
if (Session["UserItem"] == null)
Server.Execute("~/SetSessionUserObj.aspx", true);
}
... and then the SetSessionUserObj.aspx.cs
protected void Page_Load(object sender, EventArgs e) {
string ID = User.Identity.Name;
MyUser myUser = new MyUser();
UserItem userItem = myUser.GetUserItemByID(ID);
if (userItem != null) {
Session["UserItem"] = userItem;
}
}
This is just one manner that you can go about accessing a user's identity in the global.asax. You don't necessarily have to go about doing a Server.Execute to set user data (I just did it for other reasons that fall outside the scope of this question).
Good luck.
I have implement GridView Row Editing feature in my .net application using <asp:CommandField.
I clicked on Update button to save the record after editing the row.Now if i refresh the page or press F5 GridView_RowCommand fired again.
How can we avoid this.Is there any mechanism to identify when user press F5 OR refresh the page.Is there any method in client side or in server side.
Not exactly the best "technical" solution to your problem but you could always just do a Response.Redirect(Request.RawUrl) once you have finished doing anything you need to do in your RowCommand
Like I said, it's not the best "technical" solution but it is a solution
Dave
One method of capturing this is to maintain a session variable that is related to the page in question. In the session variable you would keep some kind of state enumeration, key or string that would determine the last action taken. You could even use a simple incremented counter, and if you ever received a postedback counter that was equal to the session variable it would indicate a page refresh rather than a new action.
Session["LastInsertedItem"] = null;
MyCustomObjType myCustomObject;
protected void Page_Load(object sender, EventArgs e)
{
myCustomObject = Session["LastInsertedItem"] as MyCustomObjType;
}
void GridView_RowCommand(Object sender, GridViewCommandEventArgs e)
{
If(myCustomObject == null || //!(compare your value with myCustomObject.field) )
{
// do your operations and save the values to myCustomObject and save that object back to Session.
}
else
{
// It is refreshed or same data is being insterted - don't know if second option is possible in your case.
}
}
In one of the ASP.NET MVC apps we would like to logoff the user automatically if he closes the browser tab in which the app is opened.
We are using the following code when he authenticates.
FormsAuthentication.SetAuthCookie(userName, false)
As of now, if we closes the browser window and relaunch it, users are asked to authenticate again. But we want to ask users to authenticate again if they close the tab and try to access any of the website urls.
We decided to use cookie less authentication so that the authentication token is part of the url. When the tab is closed and they open the website again, they will be asked to authenticate again :)
I have not tried this myself, but I think the following approach should work:
On the client side, you can use the OnUnload event of your document to launch a javascript function that would call your server-side signout method via ajax.
On the server side, you should have the action method call FormsAuthentication.SignOut() and Session.Abandon();
A browser clears all Session scoped objects only when it is completely closed, and not when an individual tab is closed.
One way could be to use a very low Session timeout and have a server-side script poll every few seconds to hit an object on the page. This will extend Session time again. So if a tab is closed, the script can't find the object thereby allowing the Session to timeout. One problem here is if your app is on a pretty high load, your app could DoS itself!
Actually there is no way we can LogOff the user when the user closes the browser tab. The only way for this is to check if the the user is authenticated when we call the LogOn method in the Controller.
This code is an example of how I do it in ASP.Net MVC 3.
public ActionResult LogOn()
{
if (Request.IsAuthenticated)
{
FormsAuthentication.SignOut();
return RedirectToAction("Index","ProductManager");
}
return View();
}
You can simply use session variables to automatically log off anybody trying to return to the secured destination page. Create a single session variable (integer or boolean) and in the onclick event of your login button reset it to a known state after acknowledging that the user has a valid credential then set or increment that session variable in the page_load event of the page your trying to secure. Test these values and signout the user if he is trying to return to the page or do nothing if otherwise. The code may look similar to this.
protected void btnLogin_Click(object sender, EventArgs e)
{
if (IsAuthenticated == true)
Session["IsUserLoggedIn"] = (int)0;
}
protected void Page_Load(object sender, EventArgs e)
{
if (HttpContext.Current.User.Identity.IsAuthenticated == true)
{
if (Session["IsUserLoggedIn"] != null)
{
int IsUserLoggedIn = (int)Session["IsUserLoggedIn"];
if (IsUserLoggedIn <= 0)
{
Session["IsUserLoggedIn"] = (int)IsUserLoggedIn + 1;
}
else
{
Session["IsUserLoggedIn"] = (int)0;
FormsAuthentication.SignOut();
FormsAuthentication.RedirectToLoginPage();
}
}
}
else { Session["IsUserLoggedIn"] = (int)0; }
}