How can I persist the changes of a text box when it loses focus? - asp.net

Question

I have several text boxes on a page. I want to save the text in the corresponding TextBox on LostFocus. It is to ensure the data is not lost when power failure or internet connectivity is lost. How can I accomplish something like this?

Answer 1

Another solution would be to use an UpdatePanel. You could then leverage server-side events rather than an event handler. You're markup might look something like this:
<asp:ScriptManager ID="ScriptManager" runat="server" />
<asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional" runat="server">
<asp:TextBox ID="SomeTextBox" runat="server" TextChanged="SomeTextBox_TextChanged" AutoPostBack="true" />
</asp:UpdatePanel>
</asp:ScriptManager
and then in the TextChanged handler you could do your work.
Explanation: the TextChanged event will fire on the text box in which the text was actually changed when the post back occurs. The AutoPostBack property is necessary so that the page will in fact post back when the text box loses focus.
One final thing to remember, you will probably need to leverage this.IsPostBack on the page in the Load handler because every time a control is updated it's going to reconstruct the page. It's common that logic in the Load handler only needs to execute one time, but that would pose a problem if you didn't check to see if it was a post back because then it would execute every single time you left a text box.

Answer 2

Use jquery.
First on attach blur event handler, where you call ajax method to server passing new value of the textbox.
Handle this ajax event on serverside and write your data to the database or anywhere else.
Here is a piece of code that may help.
$('#textbox_id').blur(function() {
$.ajax({url:"handler_url.ashx?textbox_value=" + $('#textbox_id').val()});
});
Then create your ashx handler on server and handle your requests with ProcessRequest method. From there you will have access to Request.QueryString where new value of textbox will be stored.