如何判断datalist 数据为空

<asp:DataList ID="DataList1" runat="server" CellPadding="4" ForeColor="#333333" >
                <ItemTemplate>
                 <dl class="movieCommentList"><dt><em><%# DataBinder.Eval(Container.DataItem,"movie_name") %></em>
                 <i><%# DataBinder.Eval(Container.DataItem,"comment_time") %></i></dt>
                 <dd><%# DataBinder.Eval(Container.DataItem,"comment_text") %></dd></dl>  
              <FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
              <AlternatingItemStyle BackColor="White" />
              <ItemStyle BackColor="#EFF3FB" />
              <SelectedItemStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />
              <HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
         <%if (this.DataList1.DataSource == null )
                { %><dl class="movieCommentList"><dt><p>暂无评论!</p><dt></dl><%} %>   
                  </ItemTemplate>    </asp:DataList> 放在的啊