How to retain Textbox values after a Postback?

Question

I have few Textbox, FileUpload and button controls within the same page. I had tried enabling the EnableViewState to True but it is still not working. The Textbox will lose its value when clicking the button to upload attachments. May I know what's wrong here, should I use ViewState to retain the values of the textboxes?

<div class="form-row">
    <div class="form-group col-md-6" >
            <asp:Label ID="lblConfiguration" runat="server" Text="Configuration*"></asp:Label>
        <asp:TextBox ID="txtConfiguration" runat="server" type="text" class="form-control" EnableViewState="true"  ViewStateMode="Enabled" ></asp:TextBox>
    </div>

    <div class="form-group col-md-12">
        <div class="col-md-6">
        <asp:FileUpload ID="fuUpload" runat="server" CssClass="nv-file-select uploader" multiple="true" /> 
            <br />
        <asp:Button ID="btnUpload" runat="server" Text="Upload" OnClick="btnUpload_Click" CssClass="btn btn-secondary" />  
    </div>
</div>

I can't find such parameter in the Page and master page. It is still not working even I enable it at page level and master page. — JL_Coder
the parameter is shown in Aristos answer. does the textbox maintain its value, if you strip down your page to the minimum, e.g. only textbox and button? — Homungus
I haven't done that. I will resort to bind the values of the controls into ViewState as the solution. — JL_Coder

Aristos Aristos · Accepted Answer · 2020-05-25T09:39:48

Possible reasons

1) You have disable the Viewstate on full page - Check on top of aspx page if its enable or not

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="FileName.ascx.cs" EnableViewState="true" %>

2) At some point on code behind you change the value on post back - so check to not change it by adding this check

if (!Page.IsPostBack)
{
    TextBox.Text = "";
}

3) For some reason after your post back you do redirect on same page.

4) For some reason you do not make post back, but reload

How to retain Textbox values after a Postback?

1 Answers

Possible reasons