How to make an ASP.NET TextBox fire it's onTextChanged event fire in an AJAX UpdatePanel?

Question

I am trying to get an textBox to fire it\'s onTextChanged event every time a keystroke is made rather than only firing only when it loses focus. I thought that adding the As

Answer 1

All the AsyncPostBackTrigger does is make sure only that portion of the page refreshes when the event is fired, it does not change when the event is fired.

I think it's possible to do what you want, but you'd need to write some javascript code to manually fire the event... and I don't even want to think about making that work.

Answer 2

• You need to call the _postback() function for your textbox control when the onkeyup is raised using javascript.
• However, since your textbox is inside your update panel, the textbox will get re-rendered everytime the user hits a key, causing the cursor to loose focus.
• This will not be usable unless you get your textbox out of the the updatepanel. That may work out for you, as update panels tend to be a bit slow, you may still have usability issues. - I would suggest using an autocomplete component.

P.S : there is one in the asp.net control toolkit or you could use the jquery autocomplete plugin which I have found to be a bit better.

Answer 3

AutoPostBack="true" OnTextChanged="TextBox1_TextChanged"

Both events are required to trigger text change event.

Answer 4

Dont Need use AJAX controls for checking the availability.. Its is not Compulsory to use it AJAX Controls.. We can use the Following Code..

<iframe>
<asp:TextBox ID="TextBox1" runat="server" AutoPostBack="true" ontextchanged="TextBox1_TextChanged"></asp:TextBox>

 protected void TextBox1_TextChanged(object sender, EventArgs e)
    {
        RequiredFieldValidator1.ErrorMessage = "";
        Label1.Text = "";
        string name = TextBox1.Text.ToString();
        string constr = "data Source=MURALY-PC\\SQLEXPRESS; database=Online; Integrated Security=SSPI";
        SqlConnection con = new SqlConnection(constr);
        con.Open();
        string query = "select UserName from User_tab where UserName='" + name + "'";
        SqlCommand cmd = new SqlCommand(query, con);
        SqlDataReader dr = cmd.ExecuteReader();
        if (dr.Read())
        {

            Label1.Text = "UserName Already Exists";
        }
        else
        {
            Label1.Text = "";
            Label1.Text = "UserName Available";
        }
        con.Close();


    }
</iframe>