I have the following DropDownList defined:
<asp:DropDownList ID="ddlStuff" CssClass="myCssClass" OnSelectedIndexChanged="PopulateAnotherDropdown" runat="server"></asp:DropDownList>
However, my PopulateAnotherDropdown method isn't firing. I have a breakpoint set on the method, and it's not being hit.
Here is my method write-up in code-behind:
public void PopulateAnotherDropdown(object sender, EventArgs e)
{
...
}
For what it's worth, the page is rendering as follows:
<select name="ctl00$MainContent$ddlStuff" id="MainContent_ddlStuff" class="myCssClass">
Any ideas?
Because you forget to add: AutoPostBack="true"
To fire the SelectedIndex of the dropdownlist control, it needs to postback to the server. For that to happen you to have to set AutoPostBack="true" in the control property.
Please Set
AutoPostBack="true"
of the dropdown.Because by default it is false except button control
Related
In my single web application, only the Page_Load(...) event is firing. I've tried using the text change event below (auto generated by double clicking the textbox):
protected void txtBuyerExtension_TextChanged(object sender, EventArgs e)
{
// do something
}
But nothing happens. It does that for every control... the only event that fires is Page_Load. How come it is doing this?
Add AutoPostBack="True"
<asp:TextBox ID="txtBuyerExtension" runat="server" OnTextChanged="txtBuyerExtension_TextChanged" AutoPostBack="True"></asp:TextBox>
You need to set the AutoPostBack property to enable TextChange event.
<asp:TextBox ID="txtBuyerExtension" runat="server" OnTextChanged="txtBuyerExtension_TextChanged" AutoPostBack="True"></asp:TextBox>
And once you change the focus from TextBox this event will fire.
<asp:TextBox ID="txtSearch" CssClass="textbox1" placeholder="Search.." AutoPostBack="true" runat="server"
OnTextChanged="txtSearch_TextChanged"></asp:TextBox>
Sorry for my ignorance, but I've always believed that setting the SelectedIndex property of a DropDownList the SelectedIndexChanged event is fired... Am I wrong?
Searching in the documentation I haven't found anything clear...
Thanks
No it cannot fire the selectionchange event.
if you are settting programatically than it not fire the selectionchange event.
DropDownlist Class Selected Index Changed Event fires when the selection from the list control changes between posts to the server.
Please make sure about following to fire the event.
AutoPostBack="true" How to use DropDownList AutoPostBack feature
onselectedindexchanged="Name of the Handler"
Below is the code.
<asp:DropDownList ID="ddl1" runat="server" AutoPostBack="true"
onselectedindexchanged="ddl1_SelectedIndexChanged">
<asp:ListItem Text ="1" Value="1"></asp:ListItem>
<asp:ListItem Text ="2" Value="2"></asp:ListItem>
</asp:DropDownList>
protected void ddl1_SelectedIndexChanged(object sender, EventArgs e)
{
}
Note - On setting the index at runtime will never fire the event.
Please go through the following links as well.
How to: Respond to Changes in List Web Server Controls
How to use DropDownList AutoPostBack feature
<asp:CheckBox ID="isSubscribed" runat="server" /> Subscribe to mailing list?<br /><br />
<asp:Button runat="server" CssClass="btn" ID="btnPrefUpdate" OnClick="updatePrefs" Text="Update" /><br /><br />
This fires in the code behind:
protected void updatePrefs(object sender, EventArgs e)
{
Response.Write(isSubscribed.Checked);
Response.End();
}
But it's always coming out as true! Whether it is checked or not! I know I'm doing it wrong, could someone show me how to access this value properly?
like #Curt said, it looks to me like you have something in your page_load. if you set the value in Page_Load make sure it is inside the following if statement
if(!Page.isPostBack)
{
isSubscribed.Checked = true;
}
You are doing it the right way. The boolean property Checked should just say True or False (I even tested it). Is your Page_Load doing something with the checkbox? In other words, is the value of the checkbox somehow (re)set when the post back is occuring (the postback of the button click).
In your Page_Load method you could include:
if (!this.IsPostBack)
{
// Set default or loaded values for controls
}
I am working with ASP.NET
I have a DropDownList item and in there i have hyperlinks as values. What event must i use in my code behind to redirect the user to that URL when he selects the "eRate" item?
My code
<asp:DropDownList ID="dropSelect" runat="server" Width="126px">
<asp:ListItem>Please select</asp:ListItem>
<asp:ListItem Value="http://www.erate.co.za">eRate</asp:ListItem>
</asp:DropDownList>
thanks in advance!!
add a onselectedindexchanged to the dropdown like this
OnSelectedIndexChanged="dropSelect_OnSelectedIndexChanged"
then codebehind you can do like this.
protected void dropSelect_OnSelectedIndexChanged(object sender, EventArgs e)
{
Response.Redirect(dropSelect.SelectedValue);
}
you can do some extra null check and all that but this is the basic idea you can use
This is driving me crazy.
I have a very simple user control:
public int? ImageId {set; get;}
protected void Page_Load(object sender, EventArgs e)
{
... do something with ImageId...
}
And then I put this control on the page with ListView within UpdatePanel:
<asp:ListView ID="ListViewImages" runat="server" DataSourceID="src">
<LayoutTemplate>
<asp:PlaceHolder ID="itemPlaceholder" runat="server" />
</LayoutTemplate>
<ItemTemplate>
<My:MyControl ImageId='<%# Eval("Id") %>' ID="cipPreview" runat="server" />
</ItemTemplate>
</asp:ListView>
The problem is Page_Load fires BEFORE ASP.NET sets ImageId. With debugger's help I found out that for some reason ImageId in MyControl IS SET, but it happens only after Page_Load has finished processing. What's wrong?
It's probably because data binding on the ListView happens AFTER Page_Load fires, so therefore your property isn't set at that point. You could move your code to PreRender event since it is called after data binding is completed.
More info according to MSDN:
PreRender -- Before this event occurs:
The Page object calls EnsureChildControls for each control and for the page.
Each data bound control whose DataSourceID property is set calls its DataBind method.