title: textbox inside a gridview lose value on postback
body: <p>in this code when i click on button all other <code>textboxes</code> that are on other row of gridview lose their values on postback what should i do ?<br>
  button add a new comment to database and rebind the gridview with a <code>AsyncPostBack</code></p>
  
  <pre><code>&lt;asp:ScriptManager ID="ScriptManager1" runat="server"&gt;&lt;/asp:ScriptManager&gt;
  &lt;asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional" runat="server"&gt;
      &lt;Triggers&gt;
          &lt;asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" /&gt;
      &lt;/Triggers&gt;
  
      &lt;ContentTemplate&gt;
          &lt;%--post GridView--%&gt;
          &lt;asp:GridView ID="posts" runat="server"&gt;
              &lt;Columns&gt;
                  &lt;asp:TemplateField&gt;
                      &lt;ItemTemplate&gt;
                          &lt;%--Comments Gridview--%&gt;
                          &lt;asp:GridView ID="comments" runat="server"&gt;&lt;/asp:GridView&gt;
                          &lt;%--a Textbox and bUtton For sending new Comment--%&gt;
                          &lt;asp:TextBox ID="TextBox1" runat="server"&gt;&lt;/asp:TextBox&gt;
                          &lt;asp:Button ID="Button1" runat="server" Text="Button" /&gt;
                      &lt;/ItemTemplate&gt;
                  &lt;/asp:TemplateField&gt;
              &lt;/Columns&gt;
          &lt;/asp:GridView&gt;
      &lt;/ContentTemplate&gt;
  &lt;/asp:UpdatePanel&gt; 
  
  
      protected void Button1_Click(object sender, EventArgs e)
  {
      //add new comment to db here then rebind gv
      posts.DataSource = GetData();
      posts.DataBind();
  }
  </code></pre>