ASP.NET

[ASP.NET C#] Postback and updatepanel issues.

9-Jun-14 6:10

If you're just looking to calculate the number of days the book is overdue, it would be better to calculate the value as required:

SQL

SELECT
    ...
    CASE
        WHEN ReturnDate >= GetUtcDate() THEN 0
        ELSE DateDiff(day, ReturnDate, GetUtcDate())
    END As DaysOverdue
FROM
    Books

Otherwise, set up a SQL job to run every night to process the books which should have been returned on the current day.

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Member 79124618-Jun-14 11:11

Member 7912461

8-Jun-14 11:11

I wrote a simple ASP/C# website using dynamic creation of controls, but when I updated VS2013, my project started having problem with displaying controls.

The problem is as follows:
http://i.imgur.com/KAwTy3e.jpg[^]

-On start, the page looks ok, but when I press any button (postback), the table on may page disappears, but the controls in cells are staying, but not in place because table disappeared, but one under the another. So the page breaks in half in my case.

It looks like this:

My Code:

public partial class _Default : System.Web.UI.Page
    {
       
//-------------------------------------------------------------------------MAIN TABLE
        Table TblMainTop = new Table();

        //TblMainTop // Contains
        TableRow TblRow_Top = new TableRow(); //Logo and login
        //MainTableCells in TblRow_Top
        TableCell TblcT_Logo = new TableCell();
        TableCell TblcT_Status = new TableCell();

        Table TblMainCenter = new Table();
        //TblMainCenter // Contains
        TableRow TblRow_Center = new TableRow(); //Navigation and source
        //MainTableCells in TblRow_Center
        TableCell TblcC_Control = new TableCell();
        TableCell TblcC_Source = new TableCell();
            
//-----------------------------------------------------------------------
        PlaceHolder PHolder = new PlaceHolder();

        Control LOGO;
        Control STATUS;
        Control CONTROL;
        private void Create_MainTable()
        {
            
            LOGO = LoadControl("~/LOGO/Logo.ascx");
            STATUS = LoadControl("~/STATUS/Login.ascx");
            CONTROL = LoadControl("~/CONTROL/Navigation.ascx");

            TblcT_Logo.Controls.Add(LOGO);
            TblcT_Status.Controls.Add(STATUS);
            TblcC_Control.Controls.Add(CONTROL);

            TblRow_Top.Cells.Add(TblcT_Logo);
            TblRow_Top.Cells.Add(TblcT_Status);
            TblRow_Center.Cells.Add(TblcC_Control);

            TblMainTop.Rows.Add(TblRow_Top);
            TblMainTop.Rows.Add(TblRow_Center);
            TblMainTop.BorderWidth = 5;

            PHolder.Controls.Add(TblMainTop);
            PHolder.ID = "Test";

                
            UpdPanel_Main.ContentTemplateContainer.Controls.Add(PHolder);
   
        }


       


        protected void Page_Load(object sender, EventArgs e)
        {
            this.Create_MainTable();
        }
    }

That’s how it looks in browser before postback:

HTML

<div id="UpdPanel_Main">
    <table id="tojeID" border="0"     
style="border-width:5px;border-style:solid;">

<!--correct content in here-->

    </table>
</div>

That’s how it looks in browser after postback:

HTML

<div id="UpdPanel_Main">
        <style type="text/css"></style>
        <div id="ctl03_PnlMainLogo"     
style="height:221px;width:1171px;"></div>
        <style type="text/css"></style>
        <div id="ctl04_PnlMainLoginState"     
style="height:221px;width:529px;"></div>
        <style type="text/css"></style>
        <div id="ctl05_PnlMainNavigation"     
style="width:301px;"></div>
</div>

Here you can download light version of my project:
http://ge.tt/6xSPKBj1/v/0

Can someone gave me any advice ? I don’t know what is going on.

Dusara Maulik9-Jun-14 2:24

Dusara Maulik

9-Jun-14 2:24

Hi,

You need to understand and use Page.IsPostBack Property[^], this may be resolve your issue

Member 79124619-Jun-14 2:53

Member 7912461

9-Jun-14 2:53

It is no use to me becouse i want to update my page all the time and it was working before as intended, and now it is not with no reason.

jkirkerx11-Jun-14 13:24

jkirkerx

11-Jun-14 13:24

You need to understand the page lifecycle.

When you create controls in Page load, they only persist 1 time. When the page post back to the server, the controls in page load will lose there values because there created again, or may not be created at all.

You need to create the controls in page.init, so the controls persist during postback.

[MSDN Page LifeCycle^]

[Code Project Page Lifecycle^]

Member 791246114-Jun-14 4:21

Member 7912461

14-Jun-14 4:21

Changed code as you suggested:

protected void Page_Init(object sender, EventArgs e)
        {
//Because I want the page to be recreated on evry postback...
            if (Page.IsPostBack)
                this.Create_MainTable();
        }

        protected void Page_Load(object sender, EventArgs e)
        {
            if(!Page.IsPostBack)
                this.Create_MainTable();
        }

But the effect is the same - table disappears but the cells are staying one under the other.
Any other suggestions ?

How to increase .net application performance

jkirkerx14-Jun-14 8:33

jkirkerx

14-Jun-14 8:33

I write in VB, but I wrote this as a quick example and tested it. The controls persist throughout the page life cycle.
Perhaps this example will give you an idea of how to write controls in code behind so that they persist.

I'm curious if others read this post, I use the With statement to include stuff like control properties.
I was not able to figure out how to use Style in the curly brackets like in the update panel, and was forced to use the control variable name instead. Lots of extra typing. If anyone knows how to add style using the curly brackets let me know.

<%@ Page 
    Title="Test" 
    Language="C#" 
    AutoEventWireup="true" 
    CodeFile="Default2.aspx.cs" 
    Inherits="Default2" %>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title></title>
</head>
    <body id="bodytag" runat="server" class="PageBackground">        
        <form id="frmDefault" runat="server">
            <asp:ScriptManager ID="ScriptManager1" runat="server" />
            <div id="wf_container" runat="server">


            </div>
        </form>
    </body>
</html>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Default2 : System.Web.UI.Page
{

    private TextBox txt_lc_userName;

    protected void Page_Init(object sender, EventArgs e)
    {

        var up_login_container = new UpdatePanel() {
            ID = "_up_login_container",
            ClientIDMode = ClientIDMode.Static,
            UpdateMode = UpdatePanelUpdateMode.Conditional,
            ChildrenAsTriggers = false
        };
        wf_container.Controls.Add(up_login_container);

        var div_login_container = new Panel();
        div_login_container.ID = "_div_login_container";
        div_login_container.ClientIDMode = ClientIDMode.Static;
        div_login_container.Style.Add(HtmlTextWriterStyle.Width, "100%");
        div_login_container.Style.Add(HtmlTextWriterStyle.Height, "400px");       
        up_login_container.ContentTemplateContainer .Controls.Add(div_login_container);

        var div_lc_username = new Panel();
        div_lc_username.Style.Add(HtmlTextWriterStyle.Width, "50%");
        div_lc_username.Style.Add(HtmlTextWriterStyle.Height, "26px");
        div_lc_username.Style.Add(HtmlTextWriterStyle.TextAlign, "left");
        div_login_container.Controls.Add(div_lc_username);

        txt_lc_userName = new TextBox();
        txt_lc_userName.ID = "_txt_lc_userName";
        txt_lc_userName.ClientIDMode = ClientIDMode.Static;
        txt_lc_userName.Style.Add(HtmlTextWriterStyle.Width, "90%");
        txt_lc_userName .Style.Add(HtmlTextWriterStyle.Height, "20px");
        div_lc_username.Controls.Add(txt_lc_userName);

        var div_lc_submit = new Panel();
        div_lc_submit.Style.Add(HtmlTextWriterStyle.Width, "50%");
        div_lc_submit.Style.Add(HtmlTextWriterStyle.Height, "46px");
        div_lc_submit.Style.Add(HtmlTextWriterStyle.TextAlign, "left");
        div_login_container.Controls.Add(div_lc_submit);

        var bt_lc_submit = new Button();
        bt_lc_submit.ID = "_bt_lc_submit";
        bt_lc_submit.Text = "Submit";
        bt_lc_submit.Click += new System.EventHandler(bt_lc_submit_click);
        div_lc_submit.Controls.Add(bt_lc_submit);

        var bt_lc_submit_trigger = new AsyncPostBackTrigger();
        bt_lc_submit_trigger.ControlID = "_bt_lc_submit";
        bt_lc_submit_trigger.EventName = "click";
        up_login_container.Triggers.Add(bt_lc_submit_trigger );


    }


    protected void Page_Load(object sender, EventArgs e)
    {

        if (!Page.IsPostBack)
        {


        }
        else
        {



        }

    }
    protected void bt_lc_submit_click(object sender, EventArgs e)
    {
        string m_userName = txt_lc_userName.Text.Trim();
        Response.Write(m_userName);


    }
}

Session for Listbox

Dalina Cheriyan6-Jun-14 3:11

Dalina Cheriyan

6-Jun-14 3:11

I want to transfer the items of a list box from one asp.net page to another. The code somehow is throwing error. I have added my code below. Please advice.

Page 1:

<asp:listbox id="SelectedItems" runat="server" visible="true" convertemptystringtonull="true" enableviewstate="true" style="margin-left: 0px" width="244px" selectionmode="Multiple" autopostback="false" appenddatabounditems="True">

<asp:button id="sbmtButton" runat="server" text="Submit" style="margin-left: 0px" width="152px" onclick="sbmtButton_Click">

Backend:

protected void sbmtButton_Click(object sender, EventArgs e)
{
Session["wrd"] = SelectedItems;
Server.Transfer("~/aftrSubmit.aspx";);
}

Page 2:
<asp:listbox id="Prescription_list" runat="server" autopostback="false" enableviewstate="true">

backend:

protected void Page_Load(object sender, EventArgs e)
{
if (!this.IsPostBack)
{

Prescription_list = (ListBox)Session["wrd"];
}
}

Re: Session for Listbox

ZurdoDev6-Jun-14 10:29

ZurdoDev

6-Jun-14 10:29

You did not provide the error nor the line of code that causes it. However, I am going to guess that it is the line that reads

Session["wrd"] = SelectedItems;

And, I'll also guess at the error. Something about not being able to serialize whatever SelectedItems is. Make SelectedItems a string of delimited values and that will work.

After looking at it more, it looks like your trying to put the whole listbox object into session. That won't work. Just make delimited string and do it that way.

There are only 10 types of people in the world, those who understand binary and those who don't.

venumadhav.narla7776-Jun-14 0:39

venumadhav.narla777

6-Jun-14 0:39

At present we deployed in production site But we are facing performance issue,
how can we increase performance.

Re: How to increase .net application performance

Richard Deeming6-Jun-14 1:01

Re: How to increase .net application performance

6-Jun-14 1:01

Profile your application;
Find the performance bottle-neck;
Tune the affected code;
Repeat until performance is acceptable;

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

thatraja6-Jun-14 9:58

thatraja

6-Jun-14 9:58

Where? Next time onwards mention some more details to get more & quick answers. Here I have consolidated bunch of things related to performance, check it out.
Improve Everything[^]

thatraja

Code converters | Education Needed | Improve Everything^New

'Submit' button related errors

Member 87616675-Jun-14 14:26

Member 8761667

5-Jun-14 14:26

Hello

In my 'register new user' ASP.NET Web form, I am experiencing two errors which I have not been able to resolve. I have a register.aspx file and a register.aspx.vb file.

I get this error in my aspx file:

BC30456: 'SubmitButton_Click' is not a member of 'ASP.account_register_aspx'.

This relates to this line:

 </div>

      <asp:Button ID="SubmitButton" runat="server" OnClick="SubmitButton_Click" Text="Register" CssClass="btn btn-default" Height="32px" />
   
    <br />
   
</asp:Content>

and in my aspx.vb file and, presumably related to the above error in my aspx file, where I have:

Protected Sub SubmitButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles SubmitButton_Click.Click.

I get the following error:

Handles clause requires a WithEvents variable defined in the containing type or one of its base types.

I have attempted to read up on Handles/WithEvents tonight, but it's a bit above me at the moment.

In context, the Handles error occurs in this snippet:

Partial Class _Register
    Inherits System.Web.UI.Page

    Protected Sub SubmitButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles SubmitButton_Click.Click. 
        Using(conn As OleDbConnection = New OleDbConnection(System.Configuration.ConfigurationManager.ConnectionStrings("usersConnectionString").ConnectionString))
        .Dim sql = "INSERT INTO userlist (username,password, strEmail) VALUES (@username,@password, @strEmail)"
        .Using cmd = New OleDbCommand(sql, conn)
        conn.Open()
        cmd.Parameters.AddWithValue("@username", txtusername.Text)
        cmd.Parameters.AddWithValue("@password", txtpassword.Text)
        cmd.Parameters.AddWithValue("@strEmail", txtstrEmail.Text)
        cmd.ExecuteNonQuery()
                End Using
            End Using
    End Sub
End Class

Any help would be appreciated.

Richard Deeming6-Jun-14 0:59

6-Jun-14 0:59

I'm assuming the extra "." on the end of your Handles line is a typo?

It sounds like your <%@ Page ... %> directive is pointing to the wrong .aspx.vb file.

Once you've got it pointing to the right file, I suspect your handler will fire either two or three times - you've connected it to the Click event in the code-behind using the Handles clause; you've connected it again in the markup with the OnClick="..." attribute; and, if you have AutoEventWireup turned on, that will connect it a third time based on the method name.

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Member 87616676-Jun-14 6:02

Member 8761667

6-Jun-14 6:02

Hello Richard

Thank you for your reply.

I take it that where I have:

<%@ Page Title="Register" Language="VB" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeFile="Register.aspx.vb" Inherits="Account_Register" %>

in my main aspx file, that 'CodeFile' must always point to the aspx.vb file and that in the aspx.vb file itself, class statements related to 'Inherit', should refer to 'Account Register' in this particular case?

Thanks.

Richard Deeming6-Jun-14 7:33

6-Jun-14 7:33

Yes, CodeFile="..." needs to point to the .aspx.vb file. The class name in the Inherits="..." attribute needs to match the name of the class defined in your .aspx.vb file.

So if you have register.aspx.vb which contains:

VB.NET

Partial Class Account_Register
    Inherits System.Web.UI.Page
    ...
End Class

Then your <%@ Page ... %> directive in register.aspx would look like:

ASP.NET

<%@ Page ... CodeFile="Register.aspx.vb" Inherits="Account_Register" %>

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer