As I understand readmore meant to show full article/description instead of two-three lines.
this can be implemented using javascript or code-behind postback.
1) Through javascript: You can have two labels first with truncated data (ie two lines) and second with full data. Second label will be hidden initially using style="display:none;". While clicking on button it will hide first label and show second one using style="display:block" and button hides as well.
<script type="text/javascript">
function showdata(btn) {
if (btn.innerText == 'Show More') {
document.getElementById('lblShort').style.display = 'none';
document.getElementById('lblLong').style.display = 'block';
btn.innerText = 'Show Less';
}
else {
document.getElementById('lblShort').style.display = 'block';
document.getElementById('lblLong').style.display = 'none';
btn.innerText = 'Show More';
}
return false;
}
</script>
<asp:Label runat="server" ID="lblShort" Text="This is some text..."></asp:Label>
<asp:Label runat="server" style="display:none;" ID="lblLong" Text="This is some text that is truncated but has more data"></asp:Label>
<asp:LinkButton runat="server" ID="lbToggle" Text="Show More" OnClientClick="javascript:return showdata(this)"></asp:LinkButton>
2) CodeBehind - Same thing can be done at code behind as well as you are hitting server then no need to have two labels you can show truncated data initially on first label and when Button postbacks you can replace content of label with full data.