Develop Reference

How to pass variable from textbox to code behind back to same page

I have a webs form page and I have a text box which once clicked passes a variable to the code behind and then back into another element of that page and I cannot get it to work.
This is the closest I have got.
<asp:Panel ID="Search" runat="server" Visible="true">
<tr>
<td>
<asp:Label ID="lblSearch" runat="server" Text="Search"></asp:Label>
</td>
<td>
<asp:TextBox ID="search" runat="server" />
</td>
<td>
<asp:RequiredFieldValidator ID="valSearch" runat="server"
ControlToValidate="movieSearch" Text="Please enter text" />
</td>
<td>
<asp:Button ID="btnSubmit" runat="server" Text="Save"
OnClick="btnSubmit_Click" />
</td>
</tr>
</table>
</asp:Panel>
<asp:Panel ID="pnlSearchResult" runat="server" Visible="false">
<script>
var search = '<%=Server.UrlDecode(Request.QueryString["Data"]) %>';
</script>
</asp:Panel>
And the code behind:
protected void btnSubmit_Click(object sender, EventArgs e)
{
if (IsValid)
{
pnlSearch.Visible = false;
pnlSearchResult.Visible = true;
Response.Redirect("search.aspx?Data=" + Server.UrlEncode(search.Text));
}
}
Also this does not change the visibility of the two panels for some reason.
I would appreciate any guidance I am very new to asp and c#.

The panel's visibility is not changing because you're forcing a new GET request to the page with this: -
Response.Redirect("search.aspx?Data=" + Server.UrlEncode(search.Text));
(I'm assuming your page is called 'search.aspx')
There's no need to do this. Remove this line.
Secondly, I see you want to force the textbox's Text value into a Javascript variable. Replace this
var search = '<%=Server.UrlDecode(Request.QueryString["Data"]) %>';
with this
var search = '<%= search.Text %>';

Write below code on page event.
Another more important point is you first panel Id is "Search" not "pnlSearch" on aspx page so please correct it
protected void Page_Load(object sender, EventArgs e)
{
if (Request.QueryString["Data"] != null)
{
Search.Visible = false;
pnlSearchResult.Visible = true;
}
}

I recommend solution without using Response.Redirect.
Code Behind Submit Button click:
protected void btnSubmit_Click(object sender, EventArgs e)
{
if (IsValid)
{
pnlSearch.Visible = false;
pnlSearchResult.Visible = true;
}
}
In Markup:
<asp:Panel ID="pnlSearchResult" runat="server" Visible="false">
<script>
var searchTxt = document.getElementById('search');
if(searchTxt.value != null && searchTxt.value != ''){
//do your stuff
}
</script>

Invalid postback or callback argument (HiddenField and container Visible=false)

I've not found answers that matched my circumstances, so I'm posting an answered question hoping it will help others.
I was getting the error
Invalid postback or callback argument. Event validation is enabled
using in configuration or <%#
Page EnableEventValidation="true" %> in a page. For security
purposes, this feature verifies that arguments to postback or callback
events originate from the server control that originally rendered
them. If the data is valid and expected, use the
ClientScriptManager.RegisterForEventValidation method in order to
register the postback or callback data for validation.
at System.Web.UI.ClientScriptManager.ValidateEvent(String uniqueId, String argument)
at System.Web.UI.Control.ValidateEvent(String uniqueID, String eventArgument)
at System.Web.UI.WebControls.HiddenField.LoadPostData(String postDataKey, NameValueCollection postCollection)
at System.Web.UI.WebControls.HiddenField.System.Web.UI.IPostBackDataHandler.LoadPostData(String postDataKey, NameValueCollection postCollection)
at System.Web.UI.Page.ProcessPostData(NameValueCollection postData, Boolean fBeforeLoad)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
I've got a Databound ListView (with a few 100s rows), with buttons on each row. The buttons bring a popup. The popup has dropdownlists and other controls doing asynchronous postbacks. I need to make sure I do asynchronous postbacks to avoid refreshing my big table.
I get the error when I click the button on one row, then change a dropdownlist inside the popup which fires a postback (selected item changed). Boom.
Here's the markup for a reduced sample, without popup and javascript at all! It still exhibits the problem. Click twice on a button in a row to get the error.
<%# Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="TestPopupAsynchPostback.Default" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<asp:ScriptManager ID="scriptMgr" runat="server" ScriptMode="Debug" EnablePartialRendering="true"
EnableScriptGlobalization="true" EnableScriptLocalization="true" EnablePageMethods="true"/>
<asp:ObjectDataSource ID="ListDataSource" runat="server" SelectMethod="List" TypeName="TestPopupAsynchPostback.Default" />
<asp:Label runat="server" ID="PageLabel"></asp:Label>
<asp:ListView ID="EL" runat="server" DataSourceID="ListDataSource" OnItemDataBound="EntityList_OnItemDataBound">
<LayoutTemplate>
<table border="1">
<tr id="itemPlaceholder" runat="server" enableviewstate="false">
</tr>
</table>
</LayoutTemplate>
<ItemTemplate>
<tr runat="server" id="DefaultRow" enableviewstate="false">
<td>
<asp:Label ID="Lbl" runat="server" EnableViewState="false" />
</td>
<td>
<button runat="server" type="button" id="ReportingButton" enableviewstate="false" onserverclick="ReportingButton_OnClick" causesvalidation="false">click</button>
</td>
</tr>
<%-- Fix part 1: Change SpecialRow visible = true--%>
<tr runat="server" id="SpecialRow" visible="false" enableviewstate="false">
<td>
<asp:Label ID="Lbl2" runat="server" EnableViewState="false" />
<asp:HiddenField runat="server" ID="fn_hid" />
</td>
</tr>
</ItemTemplate>
</asp:ListView>
</form>
</body>
</html>
Here's the code behind:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
namespace TestPopupAsynchPostback
{
public partial class Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
ScriptManager sm = ScriptManager.GetCurrent(Page);
PageLabel.Text = DateTime.UtcNow.ToString() + " IsPostBack:" + IsPostBack + " IsInAsyncPostBack:" + (sm == null ? "" : sm.IsInAsyncPostBack.ToString());
}
protected override void Render(HtmlTextWriter writer)
{
ScriptManager sm = ScriptManager.GetCurrent(this.Page);
if (sm != null)
{
foreach (ListViewDataItem row in EL.Items)
{
HtmlButton reportingButton = row.FindControl("ReportingButton") as HtmlButton;
if (reportingButton != null)
sm.RegisterAsyncPostBackControl(reportingButton);
}
}
base.Render(writer);
}
public IList<string> List()
{
return (new string[] { "ONE", "TWO"}).ToList();
}
protected void ReportingButton_OnClick(object sender, EventArgs e)
{
//Do something useful here, for now, just a postback event
}
protected void EntityList_OnItemDataBound(object sender, ListViewItemEventArgs e)
{
Label lbl = e.Item.FindControl("Lbl") as Label;
Label lbl2 = e.Item.FindControl("Lbl2") as Label;
lbl.Text = lbl2.Text = e.Item.DataItem.ToString();
HtmlTableRow specialRow = e.Item.FindControl("SpecialRow") as HtmlTableRow;
if (e.Item.DataItemIndex%2 == 0)
{
HiddenField fn_hid = e.Item.FindControl("fn_hid") as HiddenField;
fn_hid.Value = "test1";
specialRow.Visible = true;
}
//Fix part 2: set SpecialRow Visible = false in code behind
//else
// specialRow.Visible = false;
}
}
}

I initially thought my javascript was at fault as I am modifying things with it. However, the process of creating a sample page has helped me find the problem.
It turns out it has nothing to do with the javascript or the popup. It's to do with a HiddenField contained inside a TR HtmlControl (asp.net server side control) with Visible=false IN THE MARKUP. I then use the code behind to set Visible=true when I need to in OnItemDataBound event.
This is what is causing the error for me: It seems that because the container (the TR SpecialRow) is Visible=false, I guess something is not rendered. I then come along in OnItemDataBound, decide that this row must be shown, and set Visible=true and set the value of my HiddenField. Boom.
If I remove the markup for the hidden field and don't set its value, no crash.
So it's not just the visibility of the TR on its own, it's the HiddenField too.
My fix: don't set Visible=false in the markup, and change OnItemDataBound to set Visible=false when required.
In other words: I was defaulting to hide things in markup and use code behind to show them. I changed this around and show things by default in markup and hide them using the code behind.
I've added the fix in the markup and code above.

Defining the click event for a Login control integrated button

Gooday. I have a login control, with an integrated user textbox and login button. I did this little test to see how it works, and surprisingly, after doing this:
protected void LoginButton_Click(object sender, EventArgs e)
{
TextBox userTextBox = (TextBox)Login1.FindControl("UserName");
userTextBox.Text = "You pressed the button";
}
the userTextBox doesn't change to "You pressed the button". Why?
Thanks. Anna
EDIT: Sure, here is the markup (most of it is generated automatically by the system when adding the Login control); you will notice a button LoginButton integrated in the Login:
<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<asp:Panel ID="searchPanel" runat="server" DefaultButton="login1$LoginButton">
<asp:Login ID="Login1" runat="server"
FailureText="Logarea a esuat. Reincercati!" LoginButtonText="Logati-va!"
PasswordLabelText="Parola:"
PasswordRequiredErrorMessage="Trebuie sa introduceti parola."
RememberMeText="Tine-ma minte!" TitleText="Logare"
UserNameLabelText="Nume de utilizator:"
UserNameRequiredErrorMessage="Trebuie sa introduceti numele de utilizator.">
<LayoutTemplate>
<table border="0" cellpadding="1" cellspacing="0"
style="border-collapse:collapse;">
<tr>
<td>
<table border="0" cellpadding="0">
<tr>
<td align="center" colspan="2">
Logare</td>
</tr>
<tr>
<td align="right">
<asp:Label ID="UserNameLabel" runat="server" AssociatedControlID="UserName">Nume
de utilizator:</asp:Label>
</td>
.........
<tr>
<td align="right" colspan="2">
<asp:Button ID="LoginButton" runat="server" CommandName="Login"
Text="Logati-va!" ValidationGroup="Login1" />
</td>
</tr>
</table>
</td>
</tr>
</table>
</LayoutTemplate>
</asp:Login>
</asp:Panel>
</asp:Content>
The code-behind goes liek this:
namespace Cinemax
{
public partial class Login : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
//userTextBox.Focus(); // this sets the focus on the username textbox when the page loads
this.Title = CinemaxConfiguration.SiteName + ": Login";
}
protected void LoginButton_Click(object sender, EventArgs e)
{
TextBox userTextBox = (TextBox)Login1.FindControl("UserName");
TextBox userPassword = (TextBox)Login1.FindControl("Password");
//Button loginBtn = (Button)Login1.FindControl("LoginButton");
userTextBox.Text = "You pressed me";
if (User1.ConnAttempt(userTextBox.Text, userPassword.Text) == 1)
{
Session["User"] = userTextBox.Text;
Response.Redirect("Catalog.aspx");
}
else
{
}
}
}
}

Is the TestBox an ASP server control, and is runat=Server?

I might be wrong, but do you ever actually bind it back to the control.
You are creating a new textbox that is initialised from your login control.
You then set the text of that textbox, but i dont think thta will bind it back to the control itself.

If you debug the application, does it show that the text gets set?
also, do you have something in the Page_Load method that sets the text box value? you should put things in a
if(!IsPostBack)
{
userTextBox.Text = ""
}
statement

check if your control is runat=server and you have binded the control to the event
this.LoginButton.Click += new System.EventHandler(this.LoginButton_Click);

In your login control check if you are setting some value of userTextBox in Page_Load or any other event, as it appears that its value is being set from somewhere else.

you have to bind it to the Form. . .

how to display database information (evals? labels? literals?)

I have the following asp.net page
<form id="form1" runat="server">
<asp:Button id="display_button" runat="server" Text="Display" OnClick="Button1_Click" />
<asp:Button id="edit_button" runat="server" Text="Edit" OnClick="Button2_Click" />
<asp:Button id="save_button" runat="server" Text="Save" OnClick="Button3_Click" Visible="false" />
<br />
<asp:Label ID="Label1" runat="server"></asp:Label>
<br />
<asp:MultiView id="MultiView1" runat="server" ActiveViewIndex="0">
<asp:View id="View1" runat="server">
<asp:FormView id="view_program" runat="server">
<ItemTemplate>
<tr>
<td class="add_border_bold" nowrap">Status</td>
<td width="100%" class="add_border">
<img src="images/<%# Eval("status").ToString().Trim() %>_light_16.gif" alt="status" />
</td>
</tr>
<tr>
<td class="add_border_bold" nowrap">Short Title</td>
<td width="100%" class="add_border">
<%# Eval("short_title") %>
</td>
</tr>
</ItemTemplate>
</asp:FormView>
</asp:View>
<asp:View id="View2" runat="server">
<asp:FormView id="edit_program" runat="server">
<ItemTemplate>
<tr>
<td class="add_border_bold"nowrap">Status </td>
<td width="100%" class="add_border">
<asp:DropDownList id="p_status" runat="server"></asp:DropDownList>
</td>
</tr>
<tr>
<td class="add_border_bold" nowrap">Short Title</td>
<td width="100%" class="add_border">
<asp:TextBox runat="server" id="short_title" />
</td>
</tr>
</ItemTemplate>
</asp:FormView>
</asp:View>
</form>
with the following code behind page
using System;
using System.Collections;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.Common;
using System.Data.Sql;
using System.Data.SqlClient;
using System.Text;
using System.Web;
using System.Web.UI.WebControls;
namespace TM_non_deploy
{
public partial class Program : System.Web.UI.Page
{
protected Label Label1;
protected Person myPerson;
protected TestProgram myProgram;
List<TestProgram> program = null;
protected void Page_Load(object sender, EventArgs e)
{
try
{
myPerson = new Person("user");
myProgram = new TestProgram("999");
//needs to be done to refresh info on page
program = new List<TestProgram> { myProgram };
view_program.DataSource = program;
view_program.DataBind();
if (!IsPostBack)
{
//create controls and bind data
edit_program.DataSource = program;
edit_program.DataBind();
DropDownList p_status = edit_program.FindControl("p_status") as DropDownList;
p_status.Items.Add(new ListItem("Green"));
p_status.Items.Add(new ListItem("Yellow"));
p_status.Items.Add(new ListItem("Red"));
p_status.SelectedValue = myProgram.Status.Trim();
TextBox short_title = edit_program.FindControl("short_title") as TextBox;
short_title.Width = 200;
short_title.Text = myProgram.Short_Title.Trim();
}
}
catch (Exception ex)
{
Response.Write(ex);
Label1.Text = ex.ToString();
}
}
protected void Button1_Click(object sender, EventArgs e)
{
MultiView1.SetActiveView(View1);
save_button.Visible = false;
}
protected void Button2_Click(object sender, EventArgs e)
{
MultiView1.SetActiveView(View2);
save_button.Visible = true;
}
protected void Button3_Click(object sender, EventArgs e)
{
DropDownList c_status = edit_program.FindControl("p_status") as DropDownList;
myProgram.Status = c_status.SelectedValue;
bool update = myProgram.SaveTestProgram();
if (update)
{
Label1.Text = "Saved!";
//needs to be done to refresh info on page
program = new List<TestProgram> { myProgram };
view_program.DataSource = program;
view_program.DataBind();
MultiView1.SetActiveView(View1);
save_button.Visible = false;
}
else
{
Label1.Text = "Error Saving";
}
}
}
}
basically, it is one page that both displays the fields, and then on a button click displays the editable version of all those fields. my question is, should i be displaying all of the information like i am now, with evals? or should i switch to labels, or literals, or something else entirely? i want to know before i get too far and have to undo a lot of work.
there will end up being a ton of fields on this page, all types from checkboxes to dropdowns to multiline textboxes, so i want to make sure i pick the path that works best for displaying all of those different kinds of data, even though in this example i am only displaying small text information.

If you just need to display text, there's no reason not to just use your <%# Eval("title") %>
One thing that should be noted though, is that it's better to cast your DataItem and access the properties that way instead of Eval as Eval has to use reflection and is more costly (maybe to the being of actually being noticeable if you have a lot of stuff repeated).
Use: <%# (Container.DataItem as SomeObject).Title %> instead of <%# Eval("Title") %>
Kind of outside the scope of your question but just a side note. :)

I wouldn't go for ServerSide Controls (Labels/Literals) unless you need formatting or to change the control values in other server side events. They just add to ViewState (unless ViewState is disabled on those Controls).
Coming to whether it's the right approach, I would suggest you use EditItemTemplate of FormView instead of 2 FormViews in Different Views & a MultiView Control!

Need help with making label of repeater visible and link button hidden in code behind

aspx page:-
<asp:Repeater ID="rptAdd" OnItemCommand="rptAdd_ItemCommand" runat="server">
<ItemTemplate>
<td>
<asp:LinkButton ID="lnkBill" Text="Make Default" runat="server" Visible="true" CommandName="DefaultBill"></asp:LinkButton>
<asp:Label ID="labelBill" Text="Yes" Visible="false" runat="server"></asp:Label>
</td>
</ItemTemplate>
</asp:Repeater>
Code Behind:-
protected void rptAdd_ItemCommand(object source, RepeaterCommandEventArgs e)
{
if (e.CommandName == "DefaultBill")
{
Users objBill = new Users();
objBill.IsDefault = true;
e.Item.FindControl("labelBill").Visible=true;
e.Item.FindControl("lnkBill").Visible = false;
}
}
In code behind intellisense is not detecting "labelBill" and "lnkBill"..what could be wrong ?
Also need to know...that's how u access controls in a repeater ?? like using findControl() ...right ?
[EDIT]
Changed code as follows..still not working...
((Label)e.Item.FindControl("labelBill")).Visible=true;
((LinkButton)e.Item.FindControl("lnkBill")).Visible = false;
Why wont intellisense detect these two IDs??

The problem is that your controls are inside a repeater, the find control wont search recursively. Try this instead.
rptAdd.FindControl("labelBull").Visible = true;