sort data within a repeater

Yes, you can link the very same page with some query string like ?sort=field DESC and then you can use this value as the Order by expression of your repeater with a help of macros:

{% QueryString.GetValue("sort") |(identity)GlobalAdministrator%}

This is an example of what we use. Very similar to what Jan is explaining but with a few more tweaks.

In the transformation we use this method to get the sort direction to append to the header link:

<script runat="server">
    public string GetSortDirection()
    {
        string sort = ValidationHelper.GetString(HttpUtility.UrlDecode(Request.QueryString["sort"]), "");
        string[] sortString = sort.Split(' ');
        string sortDir = "asc";
        if (sortString.Length >= 2)
        {
            sortDir = sortString[1];
            if(sortDir.ToLower().Equals("asc"))
            {
                sortDir = "desc";
            }
            else
            {
                sortDir = "asc";
            }
        }
        return sortDir;
    }
</script>

Then in the actual transformation we add a placeholder so we can dynamically generate the opening table tag and the header row.

<asp:PlaceHolder ID="ph1" runat="server" Visible='<%# IsFirst() %>'>
<div class="unigrid-content">
  <table class="table">
    <thead>
      <tr class="unigrid-head">
         <th><a href="<%# CurrentDocument.NodeAliasPath %>?searchtext=<%# Request.QueryString["searchtext"] %>&searchmode=<%# Request.QueryString["searchmode"] %>&sort=<%#  "FileName+" + GetSortDirection() %>">Name </a></th>
         <th><a href="<%# CurrentDocument.NodeAliasPath %>?searchtext=<%# Request.QueryString["searchtext"] %>&searchmode=<%# Request.QueryString["searchmode"] %>&sort=<%#  "FileDate+" + GetSortDirection() %>">Date </a></th>
                 <th><a href="<%# CurrentDocument.NodeAliasPath %>?searchtext=<%# Request.QueryString["searchtext"] %>&searchmode=<%# Request.QueryString["searchmode"] %>&sort=<%#  "Attachement_1+" + GetSortDirection() %>">Attachment</a></th>       
      </tr>
    </thead>
    <tbody>
</asp:PlaceHolder>

Now we have the standard item text (or table row in our case):

<tr>
    <td><a href='<%# GetAbsoluteUrl("/getattachment/" + Eval("FileAttachment")) %>' title="Download" target="_blank"> <%# GetSearchValue("FileName") %></a></td>
    <td><%# FormatDateTime(Eval("FileDate"), "MM/dd/yyyy") %></td>
     <td><a href="<%# GetAbsoluteUrl("/getattachment/" + Eval("Attachment_1")) %>">
    &#9660;<%# Eval("Attachment1Name") %>
  </a></td>
</tr>   

Lastly, we close out the opening div and table tags using a similar approach with the placeholder.

<asp:PlaceHolder ID="ph2" runat="server" Visible='<%# IsLast() %>'>
      </tbody>
    </table>
  </div>
</asp:PlaceHolder>

Now for the configuration of the Search sort property in the webpart. We use this macro to get the "sort" querystring parameter.

`{% if(QueryString.GetValue("sort") == ""){"FileName ASC"}else{UrlDecode(QueryString.GetValue("sort"))} @%}`

Of course you will have to make modifications to your field names but for the most part this solution should work just fine.

Hi Brenden,

you can make the last part a bit cleaner using the default value:

{% UrlDecode(QueryString.GetValue("sort","FileName ASC")) @%}

Good call Jan! It's been a while since I last used that code so haven't worked through it yet to clean it up.

and how would I add the ?sort=field DESC string to URL? also it contains a space between field and DESC which is not acceptable in URLs. what should be the script to use in such case?

I don't see any problem using spaces within query string values though.