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How to create a capitalized string for a list of names in an ASP repeater

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I am using an asp repeater to display a list of names and I want to display the current letter as a grouping header type, for example on an index page.

The data is sorted alphabetically before binding, but I find it difficult to insert "A" and "B" before the names are displayed.

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5 answers


Add a Panel control to your ItemTemplate with visibility set to False. When you link the relay (assuming you are subscribing to the event ItemDataBound

), run a check to see if the first letter has changed. If set, set panel visibility to true and print a letter.

Let me know if you need some sample code.

EDIT: CODE EXAMPLE

For clarity, "AlphaHeaders" are what we will call the letters "A", "B", "C" we want to display

aspx code

The repeater will look like this:



<table>
    <asp:Repeater id="rptRepeater" runat="server" OnItemDataBound="rptNames_OnItemDataBound">
        <ItemTemplate>
            <asp:Panel id="pnlAlphaHeader" runat="server" visible="False">
               <tr><td><asp:Label id="lblAlphaHeader" runat="server" /></td></tr>
            </asp:Panel>
            <tr><td><asp:Label id="lblName" runat="server" /></td></tr>
        </ItemTemplate>
    </asp:Repeater>
</table>

aspx.cs code

First, you need a variable containing the current AlphaHeader:

private string _AlphaHeaderCurrent = String.Empty;

Then you do your work on the relay event OnItemDataBound

:

protected void rptNames_OnItemDataBound(object sender, System.Web.UI.WebControls.RepeaterItemEventArgs e)
{
   if ((e.ItemType==ListItemType.Item) || (e.ItemType==ListItemType.AlternatingItem)) {
      string name = e.Item.DataItem("Name").ToString();
      //check if the first letter of the current name is new. If it is new, we print out the header
      if(!name.StartsWith(this._AlphaHeaderCurrent)) {
         this._AlphaHeaderCurrent = name.SubString(1);                               
         ((Panel)e.ItemFindControl("pnlAlphaHeader")).Visible = true;
         ((Label)e.Item.FindControl("lblAlphaHeader")).Text = the._AlphaHeader;
      }
      ((Label)e.Item.FindControl("lblName")).Text = name;          
   }
}
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Sort before binding.

That is, bind the sorted result set.

Without seeing the values ​​that you have, it's impossible to tell exactly how to do this.



Update - from comment , I would say you need to change the binding source to something like Dictionary<string,IList<string>>

.

With a structure like this, you can bind a key (sorted) and a sublist (secondary sort).

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You need to sort the data before linking to the repeater.

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You can use nested repeaters (repeater inside a repeater). As a category and a subcategory. In the first repeater you can list all your names and make the condition start with A. Then in the sub-repeater you can show all the names. You will also use the itemdatabound event to bind the second relay.

<asp:Repeater id="rptFirstLetters" runat="server" OnItemDataBound="rptChars_OnItemDataBound">
<ItemTemplate>
    <div>"<%#Eval("letters") %>"
        <asp:Repeater id="rptNames" runat="server">
            <ItemTemplate>
                <%#Eval("names") %>
            </ItemTemplate>
        </asp:Repeater>         
    </div> // bind all letters
</ItemTemplate>

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Not a good way to do this, to be honest, repeaters usually lead to ugly code I have found. The hierarchical approach from kad1r is probably the nicest if you can customize it, but there are alternatives, depending on your implementation details; I kind of prefer this in some way since it keeps the markup very clean and since I have a boyfriend who is not a programmer which is a plus for me.

ASPX:

<%@ Page language="C#" Src="test.CODE.cs" Inherits="test_Page" %>
<asp:Repeater ID="TestRepeater" runat="server">
    <ItemTemplate>
        <asp:PlaceHolder Visible='<%# Eval("IsFirstInGroup") %>' runat="server">
            <strong><%# Eval("Initial") %></strong><br/>
        </asp:PlaceHolder>
        <%# Eval("Name") %><br/>
    </ItemTemplate>
</asp:Repeater>

CODE BEHIND:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public class test_Page : Page
{
        protected Repeater TestRepeater;

        protected override void OnInit(EventArgs e)
        {
                base.OnInit(e);

                String[] names = new String[] 
                {        
                        "Alpha, John",
                        "Altman, Mary", 
                        "Asher, Cyril",
                        "Bachman, Turner",
                        "Beta, Rob",
                        "Bexman, Norah",
                        "Clark, Freddy"
                };

                List<_DispItem> l = new List<_DispItem>();

                for (int i = 0; i < names.Length; i++)
                        l.Add(new _DispItem() { Name = names[i], IsFirstInGroup = (i == 0 || names[i - 1][0] != names[i][0]) });

                TestRepeater.DataSource = l;
                TestRepeater.DataBind();
        }

        private class _DispItem
        {
                public String Name { get; set; }
                public String Initial { get { return Name.Substring(0, 1); } }
                public bool IsFirstInGroup { get; set; }
        }
}
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