ASP.NET Change Dropdown Control ID Inside Repeater Item Dynamically
-
23-04-2021 - |
سؤال
Can someone tell me how I can get this to work. I want to distinguish dropdown controls inside a repeater control. I understand now about the lifecyle and how the buffer is already writen, but what are my alternatives? Here is what happens
Code File
Dim repeatTimes((TotalAdInsured - 1)) As Integer
myRepeater.DataSource = repeatTimes
myRepeater.DataBind()
Aspfile
<asp:Repeater ID="myRepeater" runat="server">
<ItemTemplate>
<asp:DropDownList ID="AdTitle<%# Container.ItemIndex %>" runat="server">
<asp:ListItem Selected="True" Value="" Text=""/>
<asp:ListItem Selected="False" Value="Miss" Text="Miss"/>
<asp:ListItem Selected="False" Value="Ms" Text="Ms"/>
<asp:ListItem Selected="False" Value="Mrs" Text="Mrs"/>
<asp:ListItem Selected="False" Value="Mr" Text="Mr"/>
<asp:ListItem Selected="False" Value="Other" Text="Other"/>
</asp:DropDownList>
</ItemTemplate>
</asp:Repeater>
Returns this error
Parser Error Message: 'AdTitle<%# Container.ItemIndex %>' is not a valid identifier.
المحلول
I want to distinguish dropdown controls inside a repeater control.
You don't need to. Here's some sample code that might help you out:
Markup:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Label runat="server" ID="lblMsg" Text="Click a button" />
<hr />
<asp:Repeater runat="server" ID="rptAwesome" onitemcommand="rptAwesome_ItemCommand"
>
<ItemTemplate>
<asp:Button runat="server" ID="btnAwesome"
Text='<%# "Button #" + Container.ItemIndex %>'
CommandArgument='<%# Container.DataItem %>'/><br />
</ItemTemplate>
</asp:Repeater>
</div>
</form>
</body>
</html>
Codebehind:
using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
var x = new int[] { 1, 2, 3, 4, 5 };
rptAwesome.DataSource = x;
rptAwesome.DataBind();
}
}
protected void rptAwesome_ItemCommand(object source, RepeaterCommandEventArgs e)
{
Button btnAwesome = (Button)e.CommandSource;
lblMsg.Text = string.Format("btnAwesome.ID = {0}, e.CommandArgument = {1}", btnAwesome.ID, e.CommandArgument);
}
}
نصائح أخرى
You cannot create a Unique ID inside a repeater through the markup like that. You can however retrieve the dropdown in the codebehind by using FindControl on the Repeater.
Dim adTitle As DropDownList = MyRepeater.FindControl("AdTitle")
If (Not adTitle Is Nothing) Then
''Do something here
End If
Ok... in a nutshell you can't do what you're trying to do in the manner you are currently doing it.
The ID property of a control can only be set using the ID attribute in the tag and a simple value. Example:
<asp:Button runat="server" id="Button1" />
I can see what your trying to do, but I don't really understand Why...
A repeater control will contain 1 item, per item in your datasource, so it's perfectly fine to just call your DropDownList ID="AdTitle"
as that will be a different 'AdTitle'
from the one in the next row.
To get them back server side, you would just iterate through the Items in your Repeater & FindControl("AdTitle")
to get the specific DropDownList for that item.
If it's absolutely necessary to have the IDs incrementing, you'll need to do this programmatically (probably on the ItemDataBound
event to create a DropDownList and add it to your ItemTemplate.
Expanding on BC's answer: I recently had the same issue, albeit with a checkbox, I needed to set the ID as I used that when persisting choices. A bit clunky but I did it when on Item Data Bound.
Here's the markup:
<asp:Repeater ID="Repeater1" runat="server" > <HeaderTemplate>Header<br /><br /></HeaderTemplate> <ItemTemplate> <asp:CheckBox ID="cb" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "Name") %>' /> ...other controls removed for brevity </ItemTemplate> <FooterTemplate> <asp:Button ID="Button1" runat="server" OnClick="Submit" Text="Submit" /> </FooterTemplate> </asp:Repeater>
I set up and bound a collection of this class
public class mst
{
public int Id { get; set; }
public string Name { get; set; }
public string Number { get; set; }
public bool NumberRequired { get; set; }
}
Do the necessary in Page_Load
Repeater1.ItemDataBound += new RepeaterItemEventHandler(Repeater1_ItemDataBound);
Repeater1.DataSource = listOfMsts;
Repeater1.DataBind();
Followed by, this where I set ID:
void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e) { if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem) { var mst = (mst)e.Item.DataItem; ((CheckBox)e.Item.FindControl("cb")).ID = mst.Id.ToString(); } }
So when the submit button is hit I can loop thru and grab the Id of those checked and save:
protected void Submit(object sender, EventArgs e) { foreach (var item in Repeater1.Items) { var checkboxes = ((RepeaterItem)item).Controls.OfType<CheckBox>().ToList(); if (checkboxes[0].Checked) { Save(checkboxes[0].ID); ....other stuff } } }
You could add an event handler to Repeater.ItemDataBound and create the control within the handler using the reference to the item container.