Implementing search page - asp.net

Question

I'm new to ASP.Net and trying to implement a search page in my project.
I created a simple search.aspx
<asp:TextBox runat="server" ID="txtSearch" MaxLength="250"/>
<asp:LinkButton ID="lnkSearch" runat="server" Text="Search" OnClick="Search_Click" ClientIDMode="Static" />
<asp:Repeater ID="rep" runat="server" >
....
</asp:Repeater>
and the search.aspx.cs
protected void Page_Load(object sender, EventArgs e)
{
txtSearch.Text = Request.Params["q"].ToString();
BindRepeater(); //reads Request.Params["q"] and fetches data
txtSearch.Focus();
this.Page.Form.DefaultButton = this.lnkSearch.UniqueID;
}
protected void Search_Click(object sender, EventArgs e)
{
Response.Redirect("/Search.aspx?q=" + txtSearch.Text);
}
Problem is that when I type something in txtSearch and hit enter or click search, the page reloads with the old query string and old search results, seems that txtSearch.Text is updated with old Query value before hitting Search_Click
For Example if I enter search.aspx?q=apple in address bar the page returns correct results and txtSearch's Text = "apple" .. if I type green apple and hit enter, page returns apple results, and txtSearch's Text = "apple", also the link is search.aspx?q=apple
I tried
AutoPostBack="True|False" for the TextBox
if (!IsPostBack)
txtSearch.Text = Request.Params["q"].ToString();
but I can't use it I guess since I'm posting back to same page, no?
I also tried
if (IsPostBack && txtSearch.Text != Request.Params["q"].ToString())
txtSearch.Text = Request.Params["q"].ToString();

Answer 1

This seems a strange way of doing it to me.
My preference would be to have the search logic in the event handler itself, rather than implementing this strange post-back loop.
protected void Page_Load(object sender, EventArgs e)
{
if (Page.IsPostBack == false)
{
// If passed in on first entry to the page
var searchQuery = Reqest.Params["q"];
if (String.IsNullOrWhitespace(searchQuery) == false)
{
txtSearch.Text = searchQuery;
Search_Click(null, null);
}
}
txtSearch.Focus();
this.Page.Form.DefaultButton = this.lnkSearch.UniqueID;
}
protected void Search_Click(object sender, EventArgs e)
{
// Pass the value of the search to the repeater
BindRepeater(txtSearch.Text);
}
Note that I'm passing the search text to BindRepeater so you'd have to update it to use the parameter value rather than query string