Develop Reference

ASP.net Not able to display error using label control

I am getting an error while trying to display an error message using Label control on asp.net form
what I am trying to do:
I want to show an error message using a Label control, if a user click on Submit button without selecting an option given in dropdown control and textbox control.
What I have done:
I have put code on .aspx is lblControl.Visible="true" and code on aspx.cs is inside Page_load- if(!isPostBack){ lblControl.Visible="false";
Then where I have handled the click->
if((txtbox.Text == "") & (ddlbox.SelectedItem.Text == "Select"))
{
string Message = "Please select a value in drop down list, other than 'Select' and fill some value in text box.";
lblControl.Visible = true;
lblControl.Text = Message;
/* I have tried this one code also
Page.ClientScript.RegisterStartupScript(this.GetType(), "errMsg", script, true); //doesn't help */
}
else{
save(); //another method to perform insert operation.
}
What is happening now: (As per my debug observation)
Whenever I am trying to display error message in the form of Label(control). The flow of program goes to Master page rather than display of Error message.
At the master we have placed various links related to show `logo image, ` logout link` etc `inside <%=Page.ResolveUrl("~/Modules.aspx")%>`
From there, debugging has halted & page has rendered without the message of lblContorl.
Confusion-cum-question: I am unable to understand this code-switch (flow of code getting child pages to Master pages)
many thanks for all types of suggestion!

Try the following:
Change your code to:
if(String.IsNullOrWhiteSpace(txtbox.Text) || ddlbox.SelectedItem.Text == "Select")
{
string message = "Your Error Message";
lblControl.Text = message;
lblControl.Visible = true;
return; // optional
}
else
{
save(); //another method to perform insert operation.
}
What this does is if one or both statements are true, this code will be executed. In case you do not want any other code to run after this, add 'return;' after the last line of code in your if-statement.
Another way of showing errors in ASP.Net would be to use a ValidationSummary.
With this, you do not have to worry about making controls visible or not.
Just add a ValidationSummary on your page where your Label is now - like this:
<asp:ValidationSummary runat="server" ID="myValidationSummary" CssClass="my-error-class" />
and change your code to:
if(String.IsNullOrWhiteSpace(txtbox.Text) || ddlbox.SelectedItem.Text == "Select")
{
string message = "Your Error Message";
ModelState.AddModelError("", message);
return;
}
else
{
save(); //another method to perform insert operation.
}
This way, there is no need to handle visibility and you can use this for DataBound Controls as well, so it might be worth looking into it.
EDIT: To use ModelState, you need to import ModelBinding. Just add:
using System.Web.ModelBinding;
to your Page. You can even use this in UserControls by simply calling
Page.ModelState.AddModelError("","Your Error Message");
You should be able to use this in ASP.NET without any problems.
I am unable to understand this code-switch (flow of code getting child
pages to Master pages)
See this Link to read about the ASP Page Lifecycle.

Setting Content in RadEditor

I have visited the Telerik's website and viewed their demos etc...
But I am having problems trying to load content (html) in the RadEditor.
I have a Button_Click event where I get my html string and then set it to the RadEditor. The RadEditor is inside a RadWindow and only becomes visible when the button is clicked.
protected void btnSubmitHtml_Click(object sender, EventArgs e)
{
RadEditor1.Content = "<p>hello there</p>";
RadWindow1.Visible = true;
}
This doesn't show the html inside the RadEditor for some odd reason. I suspect it is the page life cycle that is involved with this problem.
Are there any suggestions to solve this?

I have encountered this problem multiple times and never found a "Proper" resolution.
However, a great work around is to simply set the content from the clientside via injected script. The end result is the same, and if you can tolerate the 10 millisecond delay, worthy of consideration.
EDIT after comment requested reference
Basically all you need to get an instance of the editor using ASP.NET WebForms $find function. That takes the html ID of the root of the rendered object and returns the client side viewModel if one exists.
The $(setEditorInitialContent) call at the end assumes that jQuery is present and delays the execution of the function till page load.
<telerik:radeditor runat="server" ID="RadEditor1">
<Content>
Here is sample content!
</Content>
</telerik:radeditor>
<script type="text/javascript">
function setEditorInitialContent() {
var editor = $find("<%=RadEditor1.ClientID%>"); //get a reference to RadEditor client object
editor.set_html("HEY THIS IS SOME CONTENT INTO YOUR EDITOR!!!!");
}
$(setEditorInitialContent);
</script>

Take a look here to see how to get a RadEditor to work in a RadWindow: http://www.telerik.com/help/aspnet-ajax/window-troubleshooting-radeditor-in-radwindow.html.
Said shortly, here is what you need to have in the OnClientShow event of the RadWindow:
function OnClientShow()
{
$find("<%=RadEditor1.ClientID %>").onParentNodeChanged();
}

To edit Html code only you can add -
EnableTextareaMode="true"
Add this property to the RadEditor.
I suspect that the way the control tries to interpret the html might be one of the problems. The other thing that may be causing this problem is the page life cycle.

c# asp.net response.write shrinks text boxes

I have a Web Form project I am developing C# ASP.Net 4.5. I have a class that calls a response.write to display a message for user input validation purposes. The call to response.write is made inside the class in a method from creating a new instance of the class, thus the class method, by pressing a button on the form. But using the response.write causes the textboxes on my page to shrink considerably. Then when I press a different button the textboxes go back to normal. It only happens when I use response.write. Any help would be appreciated. Code call in class method:
HttpContext.Current.Response.Write("File not found");

By using that you're simply dumping text to the top of the page, typically outside of the <html> tags. This can have a knock-on effect to the rest of the pages style; i see the same when i am spitting out test responses.
Instead, put yourself a label control on your page and populate that instead. you can put it exactly where you want and simply call:
So put this: <asp:Label runat="Server" id="myLabel" /> where you want the message to appear.
Then in your code-behind, write this. It will populate the label with the given text.
myLabel.Text = "File not found";
The Label control will be rendered as a <span></span> - so styling it is nice and easy.
If you fancied using a <div> then use the Panel control.
If you're not fussed about any sort of style, go for a Literal control, which renders no html elements.

When you use the HttpContext.Current.Response.Write on code behind is direct send to the page your text, at any random point of page render.
Maybe on top, maybe on bottom, on some point that you can not control if you use the code behind to call it.
Change the way you show your message, at a minimum you can use a literal control to render there your output and show it.

You may want to use a control to display your error. For example:
In the aspx/ascx
<asp:Label id="ErrorMessage" runat="server" />
in the page/control code behind
//call TheClass
TheClass c = new TheClass();
string error = c.TheMethod();
if (!string.IsNullOrEmpty(error))
{
ErrorMessage.Text = error;
}
in TheClass
public class TheClass
{
public string TheMethod()
{
string result = "";
...
//When file is not found
result = "File not found";
...
return result;
}
}

ASP.NET Web Application Message Box

In an asp.net windows forms application, in the C# code behind you can use:
MessageBox.Show("Here is my message");
Is there any equivalent in a asp.net web application?
Can I call something from the C# code behind that will display a message box to the user?
Example usage of this: I have a button that loads a file in the code behind. When the file is loaded or if there is an error I would like to popup a message to the user stating the result.
Any ideas on this?

You want to use an Alert. Unfortunately it's not as nice as with windows forms.
ClientScript.RegisterStartupScript(this.GetType(), "myalert", "alert('" + myStringVariable + "');", true);
Similar to this question here: http://forums.asp.net/t/1461308.aspx/1

Or create a method like this in your solution:
public static class MessageBox {
public static void Show(this Page Page, String Message) {
Page.ClientScript.RegisterStartupScript(
Page.GetType(),
"MessageBox",
"<script language='javascript'>alert('" + Message + "');</script>"
);
}
}
Then you can use it like:
MessageBox.Show("Here is my message");

Here is a link from Microsoft that I think is the best way to present a MessageBox in ASP.NET
Also it presents choices like Yes and No.
Instructions on how to get the class from the link working on your project:
If you don't have an App_Code folder on your Project, create it.
Right click the App_Code folder and create a Class. Name it MessageBox.cs
Copy the text from the MessageBox.cs file (from the attached code) and paste it on your MessageBox.cs file.
Do the same as steps 2 & 3 for the MessageBoxCore.cs file.
Important: Right click each file MessageBox.cs and MessageBoxCore.cs and make sure the 'Build Action' is set to Compile
Add this code to your aspx page where you want to display the message box:
<asp:Literal ID="PopupBox" runat="server"></asp:Literal>
Add this code on you cs page where you want to decision to be made:
string title = "My box title goes here";
string text = "Do you want to Update this record?";
MessageBox messageBox = new MessageBox(text, title, MessageBox.MessageBoxIcons.Question, MessageBox.MessageBoxButtons.YesOrNo, MessageBox.MessageBoxStyle.StyleA);
messageBox.SuccessEvent.Add("YesModClick");
PopupBox.Text = messageBox.Show(this);
Add this method to your cs page. This is what will be executed when the user clicks Yes. You don't need to make another one for the NoClick method.
[WebMethod]
public static string YesModClick(object sender, EventArgs e)
{
string strToRtn = "";
// The code that you want to execute when the user clicked yes goes here
return strToRtn;
}
Add a WebUserControl1.ascx file to your root path and add this code to the file:
<link href="~/Styles/MessageBox.css" rel="stylesheet" type="text/css" />
<div id="result"></div>
<asp:ScriptManager runat="server" ID="scriptManager" EnablePageMethods="True">
</asp:ScriptManager> //<-- Make sure you only have one ScriptManager on your aspx page. Remove the one on your aspx page if you already have one.
Add this line on top of your aspx page:
<%# Register src="~/MessageBoxUserControl.ascx" tagname="MessageBoxUserControl" tagprefix="uc1" %>
Add this line inside your aspx page (Inside your asp:Content tag if you have one)
<uc1:MessageBoxUserControl ID="MessageBoxUserControl1" runat="server" />
Save the image files 1.jpg, 2.jpg, 3.jpg, 4.jpg from the Microsoft project above into your ~/Images/ path.

Not Really. Server-side code is happening on the server. You can use JavaScript to display something to the user on the client side, but it obviously will only execute on the client side. This is the nature of a client server web technology.
You're basically disconnected from the server when you get your response.

Why should not use jquery popup for this purpose.I use bpopup for this purpose.See more about this.http://dinbror.dk/bpopup/

There are a few solutions; if you are comfortable with CSS, here's a very flexible solution:
Create an appropriately styled Panel that resembles a "Message Box", put a Label in it and set its Visible property to false. Then whenever the user needs to see a message after a postback (e.g. pushing a button), from codebehind set the Labels Text property to the desired error message and set the Panel's Visible property to true.

'ASP.net MessageBox
'Add a scriptmanager to the ASP.Net Page
<asp:scriptmanager id="ScriptManager1" runat="server" />
try:
{
string sMsg = "My Message";
ScriptManager.RegisterStartupScript(Page, Page.GetType, Guid.NewGuid().ToString(), "alert('" + sMsg + "')", true);
}

As others already pointed out, a message box will be clientside Javascript. So the problem then is how to force a clientside JS message box from the server side. A simple solution is to include this in the HTML:
<script>
var data = '<%= JsData %>';
alert(data);
</script>
and to fill this data from the server side code-behind:
public partial class PageName : Page
{
protected string JsData = "your message";
Note that the string value should be a Javascript string, i.e. be a one-liner, but it may contain escaped newlines as \n.
Now you can use all your Javascript or JQuery skills and tricks to do whatever you want with that message text on the clientside, such as display a simple alert(), as shown in the above code sample, or sophisticated message box or message banner.
(Note that popups are sometimes frowned upon and blocked)
Note also that, due to the HTTP protocol, the message can only be shown in response to an HTTP request that the user sends to the server. Unlike WinForm apps, the web server cannot push a message to the client whenever it sees fit.
If you want to show the message only once, and not after the user refreshes the page with F5, you could set and read a cookie with javascript code. In any case, the nice point with this method is that it is an easy way to get data from the server to the javascript on the client, and that you can use all javascript features to accomplish anything you like.

Here's a method that I just wrote today, so that I can pass as many message boxes to the page as I want to:
/// <summary>
/// Shows a basic MessageBox on the passed in page
/// </summary>
/// <param name="page">The Page object to show the message on</param>
/// <param name="message">The message to show</param>
/// <returns></returns>
public static ShowMessageBox(Page page, string message)
{
Type cstype = page.GetType();
// Get a ClientScriptManager reference from the Page class.
ClientScriptManager cs = page.ClientScript;
// Find the first unregistered script number
int ScriptNumber = 0;
bool ScriptRegistered = false;
do
{
ScriptNumber++;
ScriptRegistered = cs.IsStartupScriptRegistered(cstype, "PopupScript" + ScriptNumber);
} while (ScriptRegistered == true);
//Execute the new script number that we found
cs.RegisterStartupScript(cstype, "PopupScript" + ScriptNumber, "alert('" + message + "');", true);
}

if you will include
System.Windows.forms
as namespace then it will conflict .
Use
btn_click()
{
System.Windows.Forms.MessageBox.Show("Hello");
}

You need to reference the namespace
using System.Windows.Form;
and then add in the code
protected void Button1_Click(object sender, EventArgs e)
{
MessageBox.Show(" Hi....");
}

Right click the solution explorer and choose the add reference.one dialog box will be appear. On that select (.net)-> System.windows.form. Imports System.Windows.Forms (vb) and using System.windows.forms(C#) copy this in your coding and then write messagebox.show("").

Just add the namespace:
System.Windows.forms
to your web application reference or what ever, and you have the access to your:
MessageBox.Show("Here is my message");
I tried it and it worked.
Good luck.

Ajax AsyncFileUpload fires server code but does not update client web page

I have an asyncfileupload control inside an update panel. The file succesfully upload and fires the correct server side code. The code on the server is exected as expected however, one line in the server code changes the text on a label. I step through the code in debug mode and the line is executed but no change is made to the page.
Here's some of the code:
<asp:UpdatePanel runat="server" ID="updater" >
<ContentTemplate>
<asp:AsyncFileUpload ID="fileUpload" runat="server" OnUploadedComplete="FileUploadComplete" />
<asp:Label ID="AsyncText" runat="server" Text="File Type not checked" />
</ContentTemplate>
</asp:UpdatePanel>
public void FileUploadComplete(object sender, AjaxControlToolkit.AsyncFileUploadEventArgs e)
{
System.Threading.Thread.Sleep(500);
if(fileUpload.HasFile) { AsyncText.Text = "file of correct format: "; }
}
Can anyone help me with solving this problem or offering annother solution??
Thanks

I think you are going to have to move toward a different solution. From your label message, it looks like you are trying to check the file type, correct? Basically, the AsyncUplaod control, although posting back to get the uploaded file to the browser, is not actually updating the page's viewstate, thus the label never gets updated. Boo! I was able to visualize this using this code in the page load event.
if (Page.IsPostBack)
{
if (Request.Files.Count > 0)
{
AsyncText.Text = "file of correct format";
ListItem item = new ListItem("item to add");
lb.Items.Add(item);
}
}
This was allowing me to set the label text but still nothing changed until I clicked on a random button that I added to the page. This button didnt even have an event in the code behind, but it was enough to cause a normal postback, and the label text and list item were successfully updated/added to the list. With that said, I would wait to update any labels until the user clicks upload by using a seperate upload button. (ie use the AsyFileUplaod to get it to the browser, but another button to save the file to the server). You can always do file evaluations in the button click event by referencing the posted files to the webpage as I did in the code above.
Some other examples I found online were using javascript to change the label text which works well also. Somthing like this:
string message = "";
if (e.StatusMessage == "Success")
{
message = "File upload successful;";
}
else
{
message = "File did not upload successfully;";
}
ClientScript.RegisterStartupScript(this.GetType(), "akey", "document.getElementByID('label').value =" + message, true);
Another example: here
I think in this case it's just the nature of the control and the only way to achieve what you want is though some creative thinking. If you have any other questions about anything I listed here feel free to ask.
Good luck!

Where is the label positioned, inside or outside the update panel? Seems like the partial page update may not be including the update to the label text. I would say move the label around as the simplest suggestion, but you could also try something like RegisterStartupScript which will change the lable text via javascript. This should still give you server side control over what text to display based on what happens during the upload.
If you could post some code that would be great.