I have a listbox in asp.net
<asp:ListBox ID="ListBox1" class="listItem" runat="server"
onselectedindexchanged="ListBox1_SelectedIndexChanged">
<asp:ListItem>1</asp:ListItem>
<asp:ListItem>2</asp:ListItem>
<asp:ListItem>3</asp:ListItem>
</asp:ListBox>
I want to trigger a function when somebody changes it values...
code which i tried is
protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e)
{
Label6.Text = Label6.Text + "hello";
}
What's wrong here..
By setting the autopostback as true, my problem is solved but the page is reloaded everytime i change its value which i dnt want as large amount of data get reloaded on every autopostback(bcoz of images on the page).Even i put the following code in page load
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
}
}
but it didnt work out...
The problem here is that you expect that the SelectedIndexChanged event is triggered immediately. But by default the ListControl's AutoPostBack property is set to false.
true if a postback to the server automatically occurs whenever the
user changes the selection of the list; otherwise, false. The default
is false.
So set it to true:
<asp:ListBox ID="ListBox1" AutoPostBack="true" class="listItem" runat="server"
onselectedindexchanged="ListBox1_SelectedIndexChanged">
<asp:ListItem>1</asp:ListItem>
<asp:ListItem>2</asp:ListItem>
<asp:ListItem>3</asp:ListItem>
</asp:ListBox>
AutoPostBack="true" is missing add it on ListBox1
Related
Inherited code with a dropdownlist which is used to populate some GridViews. When a selection is made in the dropdownlist, the selection does not keep and it jumps back up to the first record. A requently mentioned fix is to add the !Page.IsPostBack in the Page_Load event, however in doing so does not resolve the issue.
<asp:DropDownList ID="DropDownList2" runat="server" AutoPostBack="true"
DataSourceID="SqlDataSource2" DataTextField="FullAddress"
DataValueField="UniqueRecordID" Width="445px" Height="20px"
style="margin-left: 0px" TabIndex="8" AppendDataBoundItems="true"
OnSelectedIndexChanged="resetGridsAndLabel">
</asp:DropDownList>
public partial class _Default : Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
DropDownList2.DataSource = sqlDataSource2;
DropDownList2.DataBind();
}
Are you setting the data source for the DDL anywhere else on the page?
I have a simple CalendarExtender (from AjaxControlToolkit) attached to a textbox.
<asp:TextBox ID="StartDateText" runat="server" MaxLength="10" Width="70px" AutoPostBack="True" OnTextChanged="StartDateText_TextChanged" />
<asp:ImageButton ID="ImageCalendarStartDate" runat="server" ImageUrl="~/images/Calendar_scheduleHS.png" AlternateText="Click to show calendar" />
<asp:CalendarExtender ID="StartDateCalendarExtender" runat="server" TargetControlID="StartDateText" PopupButtonID="ImageCalendarStartDate" />
In order to control user input, I have the AutoPostBack set to True on the textbox, as well as a function on the TextChanged event (although TextChanged isn't the issue here).
In Page_Load, I have:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
StartDateCalendarExtender.SelectedDate = DateTime.Now.AddDays(-1);
}
}
On opening the page, Page_Load sets the date, but the AutoPostBack triggers a postback right after Page_Load, calling it again with IsPostBack set to true.
Is there a server-side way to prevent this postback?
I tried setting the AutoPostBack property to false, changing the SelectedDate, and setting it back to true, but it keeps firing a postback.
The reason is that because you give the date on the extender, then the extender add it to the text box, then the text box trigger the post back.
How about try to set the text at the TextBox at the first place.
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
// remove that
// StartDateCalendarExtender.SelectedDate = DateTime.Now;
// and direct set it to the text box.
StartDateText.Text = DateTime.Now;
}
}
Maybe you need to format the DateTime the way you want it.
After searching I've found a number of suggestions, but none of them are fixing the issue.
<asp:TextBox runat="server" ID="uid" AutoPostBack="True" Text=""></asp:TextBox>
In the properties window, EnableViewState = True for the TextBox (Suggested here). I am typing a new value into the TextBox and then hitting the Tab key. Nothing happens nor does the break point at if(IsPostBack...) break.
Code Behind:
protected void Page_Load(object sender, EventArgs e)
{
if(IsPostBack && uid.Text != "" && pw.Text == "")
{
Do stuff
}
}
UPDATE: Other TextBox setups I've tried:
<asp:TextBox runat="server" ID="uid" Text="" AutoPostBack="True" OnTextChanged="UidTextChanged"></asp:TextBox>
protected void UidTextChanged(object sender, EventArgs e)
{
ClientScript.RegisterStartupScript(GetType(), "alert", "alert('it works');", true);
}
And
<asp:TextBox runat="server" ID="uid" AutoPostBack="True" Text="" onblur="__doPostBack('','');" OnTextChanged="UidTextChanged"></asp:TextBox>
And
<asp:TextBox runat="server" ID="uid" AutoPostBack="True" Text="" onblur="__doPostBack('','');"></asp:TextBox>
Whenever AutoPostBack is set to true, I receive the following error in the browser console:
"Uncaught TypeError: Property 'submit' of object #<HTMLFormElement> is not a function
__doPostBack
(anonymous function)"
When I have the onblur property set, I receive the exact same error except instead of anonymous function it says onblur.
You could add a javascript event to the onblur for it. onblur='__doPostBack('','');'
That would cause your text box to cause a postback once it is tabbed out of.
Edit: It should be " not ' <asp:TextBox ID="TextBox1" runat="server" onblur="__doPostBack('','');" /> Just tried that and it works. Try removing the AutoPostBack="True"
Edit 2: Base on your pastebin....
<asp:Button runat="server" UseSubmitBehavior="True" ID="submit" Text="Save"
onclick="SubmitClick"/>
You can't have an ID of "submit". Change that to "btnSubmit" and the Javascript solution will work and I bet the Auopostback solution will too.
http://www.xpertdeveloper.com/2012/05/property-submit-of-object-is-not-a-function/ will explain the problem.
You can add OnTextChanged="TextBox1_TextChanged" on your textBox
Nota : It's important to set event fire, no just AutoPostBack="true".
<asp:TextBox runat="server" ID="uid" AutoPostBack="True" Text="" OnTextChanged="TextBox1_TextChanged"></asp:TextBox>
Code Behind:
protected void TextBox1_TextChanged(object sender, System.EventArgs e) {
.....
}
I want load two user controls on demand.
asp:UpdatePanel ID="UpdatePanel1" runat="server"
ContentTemplate
asp:Button ID="Button1" runat="server" Text="Button" UseSubmitBehavior="false"
OnClick="Button1_Click" /
div id='Div_UserControlPlace' enableviewstate="true" runat="server"
/div
/ContentTemplate
Triggers
asp:PostBackTrigger ControlID="Button1" /
/Triggers
/asp:UpdatePanel
asp:UpdatePanel ID="UpdatePanel2" runat="server"
ContentTemplate
asp:Button ID="Button2" runat="server" Text="Button" UseSubmitBehavior="false"
OnClick="Button2_Click" /
div id='Div_UserControlPlace2' enableviewstate="true" runat="server"
/div
/ContentTemplate
aspx.cs
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
Control FeaturedProductUserControl = new Control();
FeaturedProductUserControl = LoadControl("WebUserControl1.ascx");
FeaturedProductUserControl.EnableViewState = true;
Div_UserControlPlace.Controls.Add(FeaturedProductUserControl);
}
protected void Button2_Click(object sender, EventArgs e)
{
Control FeaturedProductUserControl2 = new Control();
FeaturedProductUserControl2 = LoadControl("WebUserControl2.ascx");
FeaturedProductUserControl2.EnableViewState = true;
Div_UserControlPlace2.Controls.Add(FeaturedProductUserControl2);
}
I load the first user control by clicking on the first button - this works properly but when I click on the other button to load the second UserControl, the first UserControl disappears and the second UserControl loads.
Thanks
IFA_User
You should use the Placeholder control to dynamically add your controls to the form.
Take a look at my last responses about dynamic controls:
OnClick event of dynamically created LinkButtons is not working
Dynamically Added DropDownlists Are Not Firing SelectedIndexChanged Event
Dynamically create an ImageButton
Now I already have some code working for demo purpose, each dynamic user controls keeps its state across post backs
This is the output:
ASPX
<asp:PlaceHolder runat="server" ID="addresses" /><br />
<asp:Button Text="Add Address" runat="server" ID="addAddress" OnClick="addAddress_Click" />
ASPX Code behind
protected void Page_PreLoad(object sender, EventArgs e)
{
for (int i = 0; i < this.DynamicControlsCount; i++)
{
var c = this.LoadControl("~/AddressControl.ascx");
this.addresses.Controls.Add(c);
}
}
protected void addAddress_Click(object sender, EventArgs e)
{
this.DynamicControlsCount++;
var c = this.LoadControl("~/AddressControl.ascx");
this.addresses.Controls.Add(c);
}
protected int DynamicControlsCount
{
get
{
if (this.ViewState["ac"] == null)
{
return 0;
}
return (int)this.ViewState["ac"];
}
set
{
this.ViewState["ac"] = value;
}
}
ASCX
<%# Control Language="C#" AutoEventWireup="true" CodeBehind="AddressControl.ascx.cs" Inherits="WebApplication1.AddressControl" %>
<asp:Panel ID="Panel1" runat="server" GroupingText="Address" DefaultButton="btnSave">
Street: <asp:TextBox runat="server" ID="txtStreet" /><br />
City: <asp:TextBox runat="server" ID="txtCity" /><br />
<asp:Button Text="Save" runat="server" ID="btnSave" OnClick="btnSave_Click" />
</asp:Panel>
<asp:Panel runat="server" GroupingText="Address Summary" Visible="false" ID="summary">
<asp:Label ID="lblStreet" runat="server" /><br />
<asp:Label ID="lblCity" runat="server" />
</asp:Panel>
ASCX Code behind
protected void btnSave_Click(object sender, EventArgs e)
{
this.summary.Visible = true;
this.lblCity.Text = "Selected city: " + this.txtCity.Text;
this.lblStreet.Text = "Selected street: " + this.txtStreet.Text;
}
When a user control is created in the HTML, asp.net will persist across postbacks without any user interaction. But if you are loading them programatically (dynamically), they will not persist accross postbacks. So if you load them programmatically, you have the added task of persisting them programmatically as well. Use the ViewState (or Session I suppose) to store what has been loaded and perhaps any other necessary information that needs to be loaded between postbacks. Every single postback will require you to reload every control or else they will disappear.
There are couple of ways of doing it:
U can load the UserControls using Ajax. Benefit of using Ajax, is ur page does not get post back, thus for example, on click event of Button1, call a ajax(traditional/Jquery) to load UserControl1, and on button click of Button2 User control2.
Put the two button in two different updated panel, by doing this the click event will only refresh a part of ur page.
U have to save somewhere (ViewState/Session),which buttons are clicked, and upon clicking of any button check the value of that variable, and explicit load the control.
Points to note - If u want to get ur data back when ur page made a complete postback, then u have to add the controls keeping in mind the Page load event cycle.
My Scenario,
When i select the option in list i need to perform some action like Textbox should be disabled. But i don find my breakpoint pointing to that action to be performed.Pls help
I guess you mean the SelectedIndexChanged event does not fire that is so because you'vent set the AutoPostBack to true.
<asp:RadioButtonList ID="RadioButtonList1" runat="server" AutoPostBack="True"
onselectedindexchanged="RadioButtonList1_SelectedIndexChanged">
</asp:RadioButtonList>
Code
protected void RadioButtonList1_SelectedIndexChanged(object sender, EventArgs e)
{
TextBox4.Enabled = false;
}