First of all, I can't use Async plugins like Jquery, Ajax, UpdatePanel, etc.
I have an ASP.NET 4 WEBFORM, In the master page I verify if the Session is lost, in that case a show a modal to get the username/password and log-in the user again.
But I've two problems, the first one is that for example if I press a button and I lost the session, the webpage show me the modal but the code behind of the clickevent still execute it and i want to prevent it (I dont want to verify the state of the session in every event handler of the APP).
The second one is that after Im success on log-in the user, i want to finish or continue the event that the user tries before he lost the session.
I other words my problem is that I need to prevent the postback in the middle of it, and then do it again. :/
Something like this:
Page_Load(...)
{
If(Session["User"] == null)
{
PostBack.Cancel(); //Like de e.PreventDefault() of Javascript.
return;
}
.
.
}
AND
LoginOnSessionLost()
{
...
//After Login Success
Postback.Continue();
}
Any suggestions? Thanks
Related
maybe some of you know the problem, that a form gets resubmitted if pressing refreshing the browser by pressing F5.
I am looking for a way to prevent this, and all I have found is the solution to do a redirect on the same page after submit
Response.Redirect(Request.RawUrl);
This DOES work, but my problem is, that I need to inject javascript into a placeholder after postback, and so this information is lost because of the Redirect.
PlaceHolder p1 = this.NamingContainer.Parent.FindControl("phPostScript") as PlaceHolder;
GenerateJsTag(script,p1);
Response.Redirect(Request.RawUrl);
Is there a way I can prevent a resubmit without Redirect?
Thanks
Is there a way I can prevent a resubmit without Redirect?
Even if there is , you should stick to that approach which is redirect after submit.
Regarding JS after post back , I believe that you want to see those JS output even after refresh after redirect.
What you can do is to redirect to Request.RawUrl+"#someValue" and then in the pageLoad (not within IsPostBack) you can inject again those scripts , knowing that you already showed that to the user via that hashkey ( could be cookie also , or query string , doesn't really matter) - or to show a message like ("Message was already accepted"...) or something like that.
Try adding following JavaScript code to your aspx page.
Also, you should not be trying to disable F5 since there are many users out there who may need to use F5 during browsing with your website.
//bind keydown event to method that disables F5
$(document).on("keydown", PreventRefresh);
function PreventRefresh(e) {
var code = e.which || e.keyCode;
if (code === 116) {
e.preventDefault();
}
}
I am trying to implement login and logout in asp.net(web forms). In my web form I have two pages namely Default and Main. From Default page when I login with username and password it redirects to the Main page. When I press back button it directly redirects to the default page. For this I copied javascript code to my default page
<script type = "text/javascript" >
function preventBack() { window.history.forward(); }
setTimeout("preventBack()", 0);
window.onunload = function () { null };
source from stackoverflow question
After login when I click on back button in my browser(chrome) first it shows the Default page and then it shows the Main page. i.e page blinks when I click the back button.
It shows main page successfully with the issue.
What should I implement to stop showing the Default page when I click on back button
Update:
<script type = "text/javascript" >
history.pushState(null, null, 'Default.aspx');
window.addEventListener('popstate', function (event) {
history.pushState(null, null, 'Default.aspx');
});
</script>
I placed this code in default page
There is one important thing that you ought to know here.
One cannot disable the browser back button functionality only thing that can be done is prevent it.
You can't, in anyway diasble that button. What you can however do, is to put some logic and prevent that button from doing what it is meant to do.
Now for the script that you have shown, it should serve fine and the other thing to try here is to put a mediator page between your default and main page. So when you login, the control will flow to mediator page and it will then redirect to main page. Now when the user presses back button on the main page, the control will flow to mediator page which will again redirect the user to his main page.
The effect will be the same as your script, but putting a page can help you write Session handling code and some server side checks if you want.
But one thing is sure, the browser back button will be as it is.
Hope this helps.
As Matt said you can't disagree the back behaviour. However you can check if the user is logged in and redirect them to the main page easily.
All you need to do is, on the default page check if the user is logged in, if they are then redirect them to the main page, this way even if the user clicks back, they will be taken back to the main page. And also the can go to the Default page after logging out.
Another way could be using location.replace("...."), which replace the existing document and user can't "go back" using back button as the page doesn't exist in the url history.
Src: https://developer.mozilla.org/en-US/docs/Web/API/Location/replace
If I have a button on my ASP.NET page which will take you to another page but that page will do something and then will send user back using
Uri uu= Request.UrlReferrer;
if (uu!= null)
Response.Redirect(uu.ToString());
Now Which page event can I use so that when other pages displays I can display a message box.
In short I am running my custom code in a "aspx" page where user is directed on button click, and then after custom code I am sending user back to old page, but it happens so quickly that user doesn't realize that he went on another page, now I want to display a message box after redirect on same page user started from, what to do :S !
More Information
EDIT
Sorry guys but I can't make changes to ASP page where button is at all
:(
I'm a bit unsure about how the Request.UrlReferrer gets set. I think it's a browser implementation detail. So I wouldn't trust on that.
I would go for something like
A.aspx -> Redirects to -> B.aspx
B.aspx -> Redirects to -> B.aspx?message=1
And check if message=1 is set.
But if you want to use the Request.UrlReferrer it should be accessible on Page_Load
If you use it this way, it'll never appear to the client.
Maybe try redirecting back using javascript with a delay so user can be informed
The best thing to do it's add a flag to the redirected page so you can show something special when the flag is turned on
Uri uu= Request.UrlReferrer;
if (uu!= null)
Response.Redirect(uu.ToString() + "?Message=DataHasChanged");
and then in the ASP page
<% if (Request.QueryString["Message"] == "DataHasChanged") { %>
<div class="alert">The data has changed. Please review it or whatever</div>
<% } %>
I get stuck in a very unusual problem. I've a code written in C# which is simply checking IsPostBack property on the Page_Load. I know that IsPostBack remains false when page lands for the first time and bocme true only when any control post the form to the server (having runat=sever).
I also know that if we hit refresh, the IsPostBack property should change to false (since refresh is not a postback).
This is the sample code:
if (!IsPostBack)
{
// If I click on any control on the page, and then hit refresh,
// the code inside this block should execute, but this is not happening.
// After first postback, I tried refreshing the page for more than
// ten times, but always finds IsPostBack=true
// ...
}
else
{
// ...
}
I clicked on a server side button (a postback), then hit refresh. I assume it will go to the if block but no luck. No matter how many times i hit Refresh on browser, IsPostBack is always true. which is truly an unusual activity I've never seen before.
I would really appreciate any help. I need to know why this is happening, is this a browser related problem or something else? I used mozilla and chrome.
Every time I hit refresh, I get a warning on both browsers.
On chrome: Confirm form submission
The page that you're looking for used info that you entered, returning to that page might cause any action you took to be repeated.Do you want to continue?
On mozilla: Confirm
To display the page, firefox must send info that will repeat any action...
Thanks in advance for any kind help.
Praveen
Most browser will do a post of the same data if you refresh after posting.
This is the meaning of the dialogues you have seen (they are asking if you want to re-post - click yes/OK means a re-post).
In order to avoid the re-post, simply go to the address bar and press enter. That will cause a new request to be issues rather than a re-post.
Those dialogs that the browsers put up tell you that they are going to do a postback instead of just get'ting the page. And you can see in your code that the warnings are accurate - any handlers that were invoked on the original postback will get invoked a second time. This is one of the main problems with postbacks - they essentially break the refresh key. If you just want to load the page, you have to mouse up to the address bar and hit enter. This will load the page with IsPostback false.
i have a doubt on how to show a popup???`
if (machineID.Count != 0)
{
checkMachineGrpState(machineID);
}
else
{
FormsAuthentication.SignOut();
Session.Abandon();
Response.Redirect("~/Default.aspx");
}
Ok now what im am doing in else statement is signing out the user and sending him back to the log out page....
I need to how him some pop up message that he is being signed out i cant figure out how to do that...
i tried messagebox but it wont work with servver and client side..
I want to use AJAX but dont know how...
any suggestions.... thanks
There are a couple of different ways you can go about this. Here's a simple example.
Your Default.aspx page will need to display the message to the user when they've logged out, so you might want a way to distinguish when you want to show the message. You could add a query string param to your redirect, like:
Response.Redirect("~/Default.aspx?ShowLogout=true");
Now on your Default.aspx page, you have a number of options. You could simply show a hidden control on the page, or write out some Javascript to show an alert box:
if (!String.IsNullOrEmpty(Request.QueryString["ShowLogout"]))
ClientScript.RegisterStartupScript(this.GetType(), "LogoutMsg", "<script>alert('You have been logged out.');</script>");
This will simply write out a script tag that runs when the user views the page. From here, you can make it more elegant by showing the user a better dialog box. For example, you could use jQuery to create a nice looking dialog box, and call the Javascript function to show it rather than calling alert in my example.