When a user clicks a button on ASP.net page, I need to
Save file from asp:fileUpload in a folder on a server - I guess this needs to be done in C#, like in How to correctly use the ASP.NET FileUpload control
Run a javascript function like in How to call javascript function from asp.net button click event
Is there a way to combine C# and Javascript to achieve what I need? If not, how should I do it?
Try using the onClientClick property of the asp:button element.
Ex, on your .aspx file:
<script type="text/javascript">
function myFunction()
{
alert('hi');
}
</script>
...
<asp:button id="Button1"
usesubmitbehavior="true"
text="Open Web site"
onclientclick="myFunction()"
runat="server" onclick="Button1_Click" />
And in your code behind (.aspx.cs)
void Button1_Click (object sender, EventArgs e)
{
if (this.FileUpload1.HasFile)
{
this.FileUpload1.SaveAs("c:\\" + this.FileUpload1.FileName);
}
}
More info at
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.button.onclientclick.aspx
Note that no JavaScript actually "runs" until the server-side code (C# in this case) has entirely completed and the resulting page is returned to the client. Once that page renders on the client, then JavaScript runs on the client.
So in order to execute your JavaScript code, all you need to do is include it in the page being returned to the client. There are a number of ways to do this, and the options depend on whether you're using WebForms or MVC.
You might use something like RegisterStartupScript in WebForms, for example. Or, you could just have the JavaScript code exist in a PlaceHolder control with Visible=false and only make the control visible in the response which intends the JavaScript code to run. (Roughly the same method is also easily usable in MVC by just wrapping the JavaScript code in a server-side condition to determine whether to render it or not.)
The main thing to remember is that you're not "running the JavaScript code from C#" or anything like that. There's a hard separation between server-side and client-side code. The server-side code ultimately builds the page that it sends back to the client, and that page can include JavaScript code to run on that client.
Related
I'm new to asp.net and I can't figure out why my onClick function isn't firing.
Here is my aspx code:
<asp:TextBox ID="TextBox1" runat="server" OnClick="TextBox1_OnClick"></asp:TextBox>
I then have a c# function that I need to run when the textbox is clicked:
protected void TextBox1_OnClick(object sender, EventArgs e)
{
//do stuff
}
You should really consider using client side coding for this scenario. why do you have to go to the server to display a calender on click of a text box. All you have to do is write whatever is to be done in a javascript file and use it in client side.
To do this, you can dothe following steps:
In your aspx page inside the <head></head> tag include
<script type="text/javascript" language="javascript" src="YourJavaScriptFile.js"></script>
In your javascript file write a function to do whatever you want (display the calender).
call that function on any event (onclick) in you aspx.
I am not giving you the code as such because
you might need a custom code for your scenario.
you will have to do a bit more research.
the basics of what is to be done has been covered.
Enjoy coding.
I'd suggest to go for Ajaxtoolkit calendar control. Have a look at demo here
The event is not firing because there is no server side onClick event for textbox! Try to wire the event up on the client side!
I have button:
html:
<asp:Button ID="MyBut" runat="server" OnClick="MyBut_Click" CssClass="MyBut" />
C#:
protected void MyBut_Click(object sender, EventArgs e)
{....}
JS:
$(document).ready(function () {
$(".MyBut").click(function () { alert("!"); });
})
Now js function is executed first, after that C# method is executed .
Can C# method be first?
Not really. The C# method is called in code-behind (you are using ASP.NET), and that gets called only upon page reload when the server executes the back-end code to form the updated page.
What you could do is to have the server-side code (the C# code) generate client-side JavaScript that would then be executed as the page reloads in the user's browser. That code would then be executed, of course, after the server-side C# code. See Inject Javascript from asp.net code behind files for an example.
Another option would be that you use AJAX to call the server-side code (so instead of code-behind). Then you can determine the sequence yourself. For more on AJAX with ASP.NET, see http://www.asp.net/ajax.
So someone clicks a button on a page, the JS fires first and then the C#? This is the only possible sequence of events. The JS on the page that handles the click of the HTML button, fires the event to the web server, and then C# runs on the web server.
I am trying to show a javascript confirm box in the middle of some server side code and after getting user confirmation continue processing but confirm box does not show up. I even wrote some sample code but no success.
after some server processing I need to ask user a question and after user confirmation continue some other server code. it seems to be very simple. even alert box work. How can I solve it?
please note that I can not call javascript confirmbox straight from buttonclick I need to do some serverside code and if that was ok then I want to show a confirmbox for continuation.
here is the code
<asp:Button ID="btn_deletefromDB" runat="server" OnClick="btn_deletefromDB_Click" Text="Delete from Datatbase);" />
protected void btn_deletefromDB_Click(object sender, EventArgs e)
{
//Delete service from Database
// some server side processing code
ScriptManager.RegisterStartupScript(Page, Page.GetType(), "confirm", "return confirm('Do you want to delete it from runtime too? Click OK to proceed.');", true);
Label1.Text = "delete from runtime confirmed";
// continue and delete from runtime
//bla bla bla
}
Instead of triggering this in the code-behind, you should add it to the Button1 OnClientClick event like so:
<asp:Button ID="Button1" runat="server" OnClientClick="return confirm('Do you want to delete it? Click OK to proceed.');" OnClick="Button1_Click" />
Web applications do not work like this. You cannot ask for user input in the middle of page's server-side life-cycle. This question has to be asked client-side and user's response has to come to the server as part of the page's submitted data.
All ScriptManager.RegisterStartupScript does is contributes to the final html content that will be sent to the client when the page completes request processing. Keep in mind that by the time this html content arrives to client computer the user may have closed the browser and gone home.
Use AJAX to submit query to server and make the server code so that it does it’s processing in two parts. I don’t have any working examples of this but this is how it would work in general. For posting data to server you can use native AJAX objects in JS or any other library as others suggested and for processing data on the server side you can use generic handlers (ashx) instead of standard web pages.
Send request to the server.
Catch the first part of the processing via JS on the client page.
Show JS window
Submit the other part to server
You’ll have to send results of the first part of processing back to the client because server will not be able to connect second request with the first one by default.
protected void addSchoolButtonClick(object sender, ImageClickEventArgs e)
{
Page.ClientScript.RegisterStartupScript(GetType(), "MyKey1", "SchoolSearchPopUp();", true);
/*Some code*/
}
I am developing a website in asp.net.At a Hyperlink onclick event i want to call a javascript function"SchoolSearchPopUp()".this function is for creating a new popup window and it is working correctly.But my problem is ,a javascript function is calling or pop window opens only after executing the rest of the code in that function and that code need's some data that occurs as a result of popup.How can i create the popup before executing the rest of code in that function.
Change your postback trigger to something within the popup.
I don't think javascript can be called from code behind. C# is running from the server and java is all client side. There's a good explanation to a similar question here: http://forums.asp.net/t/1117189.aspx
If you need to execute a javascript function, you could try changing the hyperlink to a button and making use of the OnClientClick property. This executes script client side rather than calling a method on the server.
<asp:button id="Button1"
text="Click Here"
onclientclick="SchoolSearchPopUp()"
runat="server" />
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.button.onclientclick.aspx
You will need to write JavaScript on the page to handle the click of the button first and then call to the page method on the server.
Add an OnClientClick attribute to your button element and run your JavaScript method from there:
<asp:Button ID="TestButton" OnClientClick="SchoolSearchPopup()" Text="Click Me" OnClick="addSchoolButtonClick" runat="server"/>
<script type="text/javascript">
function SchoolSearchPopup()
{
alert("Popup");
}
</script>
If you want to execute some javascript before your postback you will need to register your hyperlink's click event to a js method, then submit your post to the server after performing whatever client side logic you are looking to run. (not the other way around, using RegisterStartupScript)
Example:
$("#myHyperLink").click(function() {
// do page logic, in your case show a modal window
$("#myModalDivContainer").show();
// submit your post to the server... replace targetClientID with ID of server control you're posting to
__doPostBack('targetClientID', '');
// NOTE: If you want to perform an AJAX request instead simply use some jQuery here instead. it's up to you how to handle the request from this point :)
});
Hope this helps!
How can I write JavaScript code in asp.net in code behind using C#?
For example:
I have click button event when I click the button I want to invoke this java script code:
alert("You pressed Me!");
I want to know how to use java script from code behind.
Actually, this is what you need:
string myScriptValue = "function callMe() {alert('You pressed Me!'); }";
ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "myScriptName", myScriptValue, true);
Copy all of javascript into string and then register it into your aspx page in code-behind. Then in aspx page, you can call the javascript function whenever you want. You should write this code in Page_Load method in C# page.
Have a look at the ScriptManager class' RegisterClientScriptBlock and RegisterStartupScript methods.
One way to put some javascript onto the page into a specific location do this:
ASP.Net
<script type="text/javascript">
<asp:Literal id="litScript" runat="server" />
</script>
C#
litScript.Text = "alert("Hello!");"
Of course, you can put anything in there, and I'd recommend a javascript library.
Using the Scriptmanager is also an option.
Not an answer, but a suggestion.
Mixing your js within your code-behind can come back to haunt you, I agree with Adrian Magdas.
Anytime you need to make a simple change/update to your javascript you'll have to re-build your project, which means re-deploying instead of simply pushing out a single .js file.
Something like:
btnSomething.ClientClick = "alert('You pressed me!');";
You might also want to read up on the ScriptManager control and outputting blocks of script.
The right answers usually is "You don't". It's better to define your code in a .js file and use jQuery to hook-up the desired events.
$(document).ready(function() {
$('#myBtn').click(function() {
alert('Handler for .click() called.');
});};
If you want to register a script that will be used in connection with an UpdatePanel (AJAX) use ScriptManager class as Sani Huttunen pointed.
Otherwise you should use the class ClientScriptManager (methods Page.ClientScript.RegisterClientScriptBlock or Page.ClientScript.RegisterStartupScript)
As other user pointed, normally registering a script on the code behind can and should be avoided. It's not a very nice practice and you should do it only in cases where you have no other option.
Response.Write("<script language='javascript'>alert('You pressed Me!');</script>");