We Keep Coding

ASP.NET WebForms Confirm

I'm new to web programming with .NET.
I am developing a web page with webforms, and I want at a certain moment to programmatically show a modal window, for the user to accept or cancel, according to a question. Exactly what does the "confirm" function of JavaScript.
I tried to get it calling a JavaScript function:
Page.ClientScript.RegisterStartupScript (this.GetType (), "CallMyFunction", "MyFunction()", true);
But I need to do it without reloading the page, and I also need to control if the user has accepted or canceled and I do not know how to do it.
I've also tried getting it using the ModExPopupExtender control from DevExpress.
Can someone tell me a simple way to get what I want?
I can not understand how something so usual in web programming, and that PHP + javascript would not pose any problem can be so complicated.
All start in a one-button event on the code behind:
protected void btn1_Click(object sender, EventArgs e)
{
//I make a series of checks
//If certain conditions I want to show the confirm
//According to the user has chosen ok or cancel will perform a certain action
}
Onclientclick does not help me because before launching the "confirm" I have to do some checks on the server side.
Thank you very much.

You can use OnClientClick which is a property on most web controls.
I like to just bring up a simple confirm() dialog which executes the server code if the user clicks OK and does nothing if the user cancels the action:
<asp:Button runat="server" ID="btnSave" Click="btnSave_Click" Text="Save"
OnClientClick="return confirm('Are you sure you want to do this thing?');" />
You can do other things with it as well, but the key thing to remember is that anything you do in OnClientClick will happen before the page gets posted back to the server.
This is also perfectly valid:
<asp:Button runat="server" ID="btnSave"
OnClientClick="showModalConfirm('some message goes here');" ... />
<script>
function showModalConfirm(msg)
{
$(".modal .message").innerHtml(msg);
$(".modal").Show();
}
</script>
You can set the action that OnClientClick should perform in your codebehind in exactly the same way:
protected void Page_Load(object sender, EventArgs e)
{
btnSave.OnClientClick = "return confirm('Are you sure you want to do this thing?');";
}

You can use below code in c# to call javascript function. Below code will execute afterpostback() javascript function:
ClientScript.RegisterStartupScript(GetType(), Javascript, "javascript:afterpostback();", true);
And you can write code in javascript function to display any div or popup:
<script language="javascript" type="text/javascript">
function afterpostback() {
//Here you can write javascript to display div/modal
}
</script>

One way I've handled this previously was to have 2 buttons on the page. The first would be initially visible and labeled "Submit". The second would be initially hidden and labeled "Confirm". The "Submit" button would postback upon click and perform your server side checks/validation. If those checks failed, an appropriate error message would be displayed. If those checks passed, an appropriate "Please confirm your submission"-type message would be displayed, the "Submit" button would become hidden, and the second "Confirm" button would become visible. When that Confirm button was clicked, it would postback again and fully submit.
EDIT: I forgot to mention, there's a bit more to this that occurred to me after I initially posted. You'll have to protect the fields from being edited in the event the server-side verification is successful as you obviously don't want the user changing values and then clicking the Confirm button. That means disabling all the input controls - which could be a pain if you have a lot. You also have to give them a way to (intentionally) Edit in case the server side verification passes, you display the Confirmation, and they change their minds - so basically you'd need a third "Cancel/Edit"-type button that would put the form back in edit mode and show your initial Submit button.

How do I prevent double submit of linkbutton?

How can I prevent double submit of link button. I have a payment button, I want to disable it as soon as somebody clicks on it and re-enable it if the payment fails. I am using AJAX and programmatic post to payment gateway.
I can disable the linkbutton using this code:
asp:LinkButton ID="btnPayment" runat="server" onClientClick="this.disabled=true;__doPostBack(this.id,'');" Text='<%#Databinder.Eval(Container.DataItem,"Author")%>' ></asp:LinkButton>
But how do I enable it back when payment fails?

I think in the button click handler if the payment failed you can write the code to execute javascript like:
ScriptManager.RegisterStartUpScript(this.Page, typeof(Page) , "enableBtn" , "$('[$=btnPayment].removeAttr(disabled)')" , true);
This requires jquery.
ALternatively you can call document,getelementbyID also if you dont want to use jquery.
Let me know if this is not what you want
I have a one more solution but that seems to be nasty:
In the beginning
<asp:LinkButton ID="btnPayment" runat="server" Text='<%#Databinder.Eval(Container.DataItem,"Author")%>' ></asp:LinkButton>
And using jquery do this:
$(document).ready(function() { $('id$=btnPayment').live("click", function(e) {
$(this).attr("disabled", "disabled");
__doPostBack($(this).attr("id"),'');
e.preventDefault();
}); });
So with Ajax you removed the disabled attribute so the link button becomes clickable again.
Will this make sense

In code behind, You can enable and disable code.
On click, first disable link button and enable it if payment succeed.
because above code will also do server trip, ajax call is not firing.
btnLogin.Enabled = false;
if (txtUserName.Text == "hh") btnLogin.Enabled = true;

Why won't my form post back after validation?

I have an asp.net page with multiple validation summaries setup with ShowMessageBox="True" and several validators. I have run into a situation where when validation fails the validation summary displays correctly but then the next click that would normally trigger a postback of the page does not trigger a postback. So the steps look like this:
Click button that triggers validation.
Validation fails and a messagebox with the failure message is displayed.
Click a different button which does not validate but should trigger a postback nothing happens
Click same button as step 3 again postback happens as expected.
What could cause this behavior?
EDIT: The validation was being done in the following manner. In the asp page:
<asp:Button runat="server" id="btn" onClientClick="return DoValidation();" />
In the javascript:
function DoValidation() {
if (!Page_ClientValidate('group1'))
return false;
if (!Page_ClientValidate('group2'))
return false;
return true;
}

After working on this and making careful use of the debugger I finally found out that when you do validation the way described in the edit to the question a boolean is set on failure that blocks the next PostBack of the page from going through. I believe this is done when validation is being done automatically instead of explicitly as I'm doing here. Changing the javascript described above to look like this:
function DoValidation() {
if (!Page_ClientValidate('group1')) {
Page_BlockSubmit = false;
return false;
}
if (!Page_ClientValidate('group2')) {
Page_BlockSubmit = false;
return false;
}
return true;
}
Causes the problem to go away. Hopefully this will help the next person who makes the same mistake I did.

Want to show a message box using javascript

Hi everyone I have a web form in which I am having a button on clicking which data back up is being taken, I used the following javascript :
<script language="javascript" type="text/javascript">
function showPleaseWait() {
document.getElementById('PleaseWait').style.display = 'block';
}
</script>
<asp:Button ID="btnTakebackup" runat="server" Text="Take Backup" Enabled="true"
onMouseDown="showPleaseWait()" CausesValidation="false" />
<div id="PleaseWait" style="display: none;">"Please Wait Backup in Progress.."</div>
Hi I am using a button to take a back up.
Now I want to show a message in btnTakebackup_Click() event, whether Back up was successful or not.
I used Response.Write("<script>alert('abcd');</script>"); in btnTakebackup_Click() event.
But the problem is that I want to show the page also, which is not showing instead white background is showing.
Thanks in advance...

To show a message box alert should be able to write out a new script to the response stream:
var script =
"<script type=\"javascript\">" +
"alert(\"Backup in progress, don't go!\");" +
"</script>"
Response.Write(script);
However much this is distasteful, I suppose it is sometimes "necessary".

You can add client side event handlers to ASP controls:
How to: Add Client Script Events to ASP.NET Web Server Controls
Cheers.

Do you really want it to be an alert? (You should know that they lock up the whole browser not just the tab your page is on), do your users really need to acknowledge the backup success by clicking ok or just be informed of it?...
I suggest you have a div on the page that says "Backup successful". The visibility of which can be set by a boolean property BackUpSuccess which you can set to true in the code behind you mention.
<div id="backUpSuccess" <%=BackUpSuccess ? "" : "style='display:none;'"%>>
Backup was successfull
</div>
...you can style the div as you like in your .css file to get attention.
If you really do want an alert you could run some JavaScript on page load to check the content of a hidden input that you set server side in similar fashion...but running javascript on page load is tricky...unless your using jQuery and then you will know it's very easy.

From your question, I understood that after clicking on the button, the data back up is happening, but the alert is not displaying as soon as you clicked the button.This is because you are calling the JavaScript in the button click event which will be fired only after all the code in the button click is executed.I suggest you to add a JavaScript function in the .aspx source page it self and call the JavaScript function as shown below:
<script ...>
function xyz()
{
alert('Please Wait');
}
</script>
and in button declaration
<asp:button id='btn_submit' runat="server" OnClientClick="return xyz();" />

Display a "Yes / No" alert box in C# code behind

I am trying to display a "Yes / No" messagebox from codebehind in C#. I want to call an "AddRecord" procedure if the user clicks "Yes", and do nothing if the user clicks "No".
Ideally, I want to use the code below, but from codebehind:
OnClientClick = "return confirm('Are you sure you want to delete?');"
I search on SO and google, but was not able to find anything helpful.

on your Add Record button, just do the following:
<asp:button ID="AddRecordbutton" runat="server" Text="Add Record"
onclick="AddRecordButton_Click" onclientclick="return confirm('add record?');" />
In your code behind, just put the add record code in your AddRecordButton_Click event handler. It will only be called if they click Yes on the popup.
Alternatively, you could have your codebehind assign the onclientclick code when the button is initially rendered.
For example:
protected void Page_Load(object sender, EventArgs e) {
AddRecordButton.OnClientClick = #"return confirm('Add Record?');";
}

No, you don't.
You seem to be misunderstanding that basic concept of webpage.
An ASPX page is a short program, which starts-up, generates seem HTML, and then terminates. The HTML is then sent across the Internet to the users browser. EVERYTHING you do in a codebehind must be complete before the user ever sees any of it.
You really want a javascript dialog box. (Actually, from what you describe, you could just create a messagebox-looking div in HTML with a standard HTML form on it.)

To display an actual messagebox you will need javascript as it is done on the client-side. For whatever reason, if you cannot use javascript, you could do what AEMLoviji has suggested and "fake" it with some cleverness.
Note that you do not need jQuery to display a messagebox, simple javascript will suffice.

If you use the Ajax Control Toolkit Modal Popup Extender on a Panel with your two buttons this will fire an event on the server which can be handled and execute whichever method/functions you wish
See here for an example

Use RegisterStartupScript
ScriptManager.RegisterStartupScript(this, GetType(), "unique_key",
"element.onclick = function(){ return confirm('Are you sure you want to delete?'); };",
true);

To show yes/no
<script>
function AlertFunction() {
if (confirm('Are you sure you want to save this thing into the database?')) {
$('#ConfirmMessageResponse').val('Yes');
} else {
$('#ConfirmMessageResponse').val('No');
}
}
</script>
to handle it from .net side:
string confirmValue = ConfirmMessageResponse.Value;
if (confirmValue == "Yes")
{...}