How to use a buttonfield in a gridview - asp.net

Question

I am using this gridview:
<asp:GridView ID="gvMessages" runat="server" AutoGenerateColumns = "false"
CaptionAlign="NotSet" CellPadding="5" onrowcommand="gvMessages_RowCommand">
<Columns>
<asp:TemplateField HeaderText="Avändare">
<ItemTemplate>
<%# GetSender((int)Eval("Sender"))%>
<br />
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Ämne">
<ItemTemplate>
<%# Eval("Head")%>
<br />
</ItemTemplate>
</asp:TemplateField>
<asp:ButtonField Text="Öppna" CommandName="Open" />
</Columns>
</asp:GridView>
I want a textbox to show the message member of the bound object (Eval("Message")) of the row that has been clicked.

Answer 1

from the comments, and I would suggest to have the show/hide in the client, so you can save a round trip to the server
<asp:GridView ID="gvMessages" runat="server" AutoGenerateColumns = "false"
CaptionAlign="NotSet" CellPadding="5">
<Columns>
<asp:TemplateField HeaderText="Avändare">
<ItemTemplate>
<%# GetSender((int)Eval("Sender"))%>
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField HeaderText="Ämne" DataField="Head" />
<asp:TemplateField HeaderText="Avändare">
<ItemTemplate>
<button class="btn-showmsg">Öppna</button>
<div class="message hide">
<asp:TextBox runat="server"
TextMode="MultiLine" Text="<%= Eval("Message") %>" />
</div>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
and in javascript
$(function() {
$(".btn-showmsg").click(function() {
var tr = $(this).closest("tr"), // the <tr>
msg = tr.find(".message"); // the div wraping the message
msg.show(); // show it
});
});
Now, the position and the placement of the message, it's all up to you, but I would suggest something like Bootstrap Modal to show it.
also, remember to add a style of .hide { display: none; }