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Not able to store information while postback after creating dynamic dropdown in ASP.NET

here is my code
after button 2 click event it is creating the dropdown in table rows but when I try to save by button 1 click event it just disappear. I have not find any solution regarding this. I have used find control view State etc but it's not helping.
I want to store selected values of dropdown after button_1 click event starts.
public partial class StudentClassSectionMapping : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
ClassCode.Enabled = false;
}
}
protected void Button2_Click(object sender, EventArgs e)
{
UpdateModalShowFlag.Value = "true";
Check.Value = "true";
CreateTableRows();
}
private void CreateTableRows()
{
long h = long.Parse(LinkButtonIdCarrier.Value);
List<StudentsClassSectionMapping.StudentsClassSectionMappingForm> allStudentsInClass = StudentsClassSectionMapping.GetStudentsinClass(h);
ClassMaster.ClassMasterForm classCode = Schoolclasses.GetInfo(h);
ClassCode.Text = classCode.cCode;
List<StudentsClassSectionMapping.StudentsClassSectionMappingForm> allSectionsInClass = StudentsClassSectionMapping.GetSectionsinClass(h);
foreach (StudentsClassSectionMapping.StudentsClassSectionMappingForm studentList in allStudentsInClass)
{
TableRow row = new TableRow();
TableCell cell1 = new TableCell();
TableCell cell2 = new TableCell();
TableCell cell3 = new TableCell();
DropDownList t = new DropDownList();
t.Items.Add("No Section");
foreach (StudentsClassSectionMapping.StudentsClassSectionMappingForm sectionList in allSectionsInClass)
{
t.Items.Add(sectionList.ssSection);
t.Items[t.Items.Count - 1].Value = sectionList.ssSectionID.ToString();
}
t.Attributes.Add("class", "form-control");
t.ID = studentList.ssStudentId.ToString();
cell1.Text = studentList.ssName;
cell2.Text = studentList.ssRegistrationNumber;
cell3.Controls.Add(t);
row.Cells.Add(cell1);
row.Cells.Add(cell2);
row.Cells.Add(cell3);
Table1.Rows.Add(row);
}
}
protected void Button1_Click(object sender, EventArgs e)
{
CreateTableRows();
long h = long.Parse(LinkButtonIdCarrier.Value);
List<StudentsClassSectionMapping.StudentsClassSectionMappingForm> allStudentsInClass = StudentsClassSectionMapping.GetStudentsinClass(h);
foreach (StudentsClassSectionMapping.StudentsClassSectionMappingForm studentList in allStudentsInClass)
{
DropDownList d = Table1.FindControl(studentList.ssStudentId.ToString()) as DropDownList;
if (d != null)
{
if (d.SelectedIndex != 0)
{
StudentsClassSectionMapping.StudentsClassSectionMappingForm studentSectionMapping = new StudentsClassSectionMapping.StudentsClassSectionMappingForm();
studentSectionMapping.ssClassId = h;
studentSectionMapping.ssStudentId = studentList.ssStudentId;
studentSectionMapping.ssStudentId = long.Parse(d.SelectedItem.Value);
StudentsClassSectionMapping.addSectionStudentMapping(studentSectionMapping);
}
else
{
StudentsClassSectionMapping.StudentsClassSectionMappingForm studentSectionMapping = new StudentsClassSectionMapping.StudentsClassSectionMappingForm();
studentSectionMapping.ssClassId = h;
studentSectionMapping.ssStudentId = 0;
studentSectionMapping.ssStudentId = 0;
StudentsClassSectionMapping.addSectionStudentMapping(studentSectionMapping);
}
}
}
}

It get vanished/disappear because you added it dynamically on page. If you want it back or want to reserver control which is dynamically created you need to recreate again and need to add dynamically.
Here is good example of how you can do it : How to create controls dynamically in ASP.NET and retrieve values from it

ASP.NET GridView does not update its row

I followed this tutorial on MSDN for ASP.NET GridView Update Row, but it does not work.
updatedItem.DepartureCity = ((TextBox)(row.Cells[2].Controls[0])).Text;
Still gives the original value from the cell and not the updated one.
public partial class ManagePage : System.Web.UI.Page
{
BusScheduleModelContainer modelContainer = new BusScheduleModelContainer();
protected void Page_Load(object sender, EventArgs e)
{
//FormsAuthentication.RedirectFromLoginPage()
//if (!HttpContext.Current.User.Identity.IsAuthenticated)
//{
// Server.Transfer("LoginPage.aspx");
//}
resultsGridView.DataSource = modelContainer.BusRoutes.ToList();
resultsGridView.DataBind();
}
protected void RowDeleting(object sender, GridViewDeleteEventArgs e)
{
var routeID = int.Parse(e.Values[0].ToString());
var removedItem = modelContainer.BusRoutes.FirstOrDefault(
item => item.RouteID == routeID);
if (removedItem != null)
{
modelContainer.BusRoutes.Remove(removedItem);
resultsGridView.DataSource = modelContainer.BusRoutes.ToList();
resultsGridView.DataBind();
modelContainer.SaveChanges();
}
}
protected void RowUpdating(object sender, GridViewUpdateEventArgs e)
{
var routeID = int.Parse(e.NewValues[0].ToString());
var updatedItem = modelContainer.BusRoutes.FirstOrDefault(
item => item.RouteID == routeID);
if (updatedItem != null)
{
GridViewRow row = resultsGridView.Rows[e.RowIndex];
var res = row.FindControl("ctl00$ContentPlaceHolder1$resultsGridView$ctl02$ctl03");
updatedItem.DepartureCity = ((TextBox)(row.Cells[2].Controls[0])).Text;
updatedItem.ArrivalCity = ((TextBox)(row.Cells[3].Controls[0])).Text;
updatedItem.DepartureTime = DateTime.Parse(((TextBox)(row.Cells[4].Controls[0])).Text);
updatedItem.ArrivalTime = DateTime.Parse(((TextBox)(row.Cells[5].Controls[0])).Text);
}
resultsGridView.EditIndex = -1;
BindData();
}
protected void RowEditing(object sender, GridViewEditEventArgs e)
{
//Set the edit index.
resultsGridView.EditIndex = e.NewEditIndex;
//Bind data to the GridView control.
BindData();
}
protected void RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
//Reset the edit index.
resultsGridView.EditIndex = -1;
//Bind data to the GridView control.
BindData();
}
private void BindData()
{
resultsGridView.DataSource = modelContainer.BusRoutes.ToList();
resultsGridView.DataBind();
}
}
<div>
<asp:GridView runat="server" ID="resultsGridView"
AutoGenerateColumns="true" AllowPaging="true"
AutoGenerateDeleteButton="true" OnRowDeleting="RowDeleting"
AutoGenerateEditButton="true" OnRowUpdating="RowUpdating"
OnRowEditing="RowEditing" OnRowCancelingEdit="RowCancelingEdit">
</asp:GridView>
</div>

Do you use CommandField for update controler?
If so, when you click update button, first it will do Page_Load event handler, after that do the implementation in RowUpdating event handler.
You should try to check post back in Page_Load event handler like this:
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
resultsGridView.DataSource = modelContainer.BusRoutes.ToList();
resultsGridView.DataBind();
}
}
By this way, it will bind data to the GridView only first time you open this page.
For post back event such as clicking update button, it will not bind the original data to GridView again.

In RowUpdating method you need to add modelContainer.SaveChanges(); like below:
if (updatedItem != null)
{
GridViewRow row = resultsGridView.Rows[e.RowIndex];
var res = row.FindControl("ctl00$ContentPlaceHolder1$resultsGridView$ctl02$ctl03");
updatedItem.DepartureCity = ((TextBox)(row.Cells[2].Controls[0])).Text;
updatedItem.ArrivalCity = ((TextBox)(row.Cells[3].Controls[0])).Text;
updatedItem.DepartureTime = DateTime.Parse(((TextBox)(row.Cells[4].Controls[0])).Text);
updatedItem.ArrivalTime = DateTime.Parse(((TextBox)(row.Cells[5].Controls[0])).Text);
modelContainer.SaveChanges();
}

Gridview Edit/Update is not working?

Here i am updating the gridview value but the value is not updating..TextBox txtID,TextBox txtName,TextBox txtAge retains the older value only and the value is not getting updated..Can anyone tel me like what am i doing wrong here
Here is my code
protected void gvTemp_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
CreateDataSkeletton(Convert.ToInt16(Session["intTabIndex"]));
GridViewRow row = (GridViewRow)gvTemp.Rows[e.RowIndex];
int autoid = Int32.Parse(gvTemp.DataKeys[e.RowIndex].Value.ToString());
int id = Convert.ToInt32(gvTemp.DataKeys[e.RowIndex].Values[0].ToString());
activeTabIndex = Convert.ToInt16(Session["activeTabIndex"]);
TextBox txtID = ((TextBox)gvTemp.Rows[e.RowIndex].FindControl("txtId"));
TextBox txtName = (TextBox)gvTemp.Rows[e.RowIndex].FindControl("txtName");
TextBox txtAge = (TextBox)gvTemp.Rows[e.RowIndex].FindControl("txtAge");
dataSetInSession.Tables["Days" + activeTabIndex.ToString()].Rows[e.RowIndex]["ID"] = txtID.Text;
dataSetInSession.Tables["Days" + activeTabIndex.ToString()].Rows[e.RowIndex]["Name"] = txtName.Text;
dataSetInSession.Tables["Days" + activeTabIndex.ToString()].Rows[e.RowIndex]["Age"] = txtAge.Text;
gvTemp.DataSource = dataSetInSession.Tables["Days" + activeTabIndex.ToString()];
gvTemp.DataBind();
gvTemp.EditIndex = -1;
}
and
private void CreateDataSkeletton(int intTabIndex)
{
dataSetInSession = new DataSet();
Session["intTabIndex"] = intTabIndex;
if (Session["dataSetInSession"] != null)
{
dataSetInSession = (DataSet)Session["dataSetInSession"];
}
if (dataSetInSession.Tables["Days" + intTabIndex].Rows.Count > 0)
{
gvTemp.DataSource = dataSetInSession.Tables["Days" + intTabIndex];
gvTemp.DataBind();
}
else
{
gvTemp.DataSource = dataSetInSession.Tables["Days"];
gvTemp.DataBind();
}
temp.Controls.Add(gvTemp);
}
Any suggestion??
EDIT(1):
protected void Page_Init(object sender, EventArgs e)
{
if (!IsPostBack)
{
AddDataTable();
}
dataSetInSession = new DataSet();
if (Session["dataSetInSession"] != null)
{
dataSetInSession = (DataSet)Session["dataSetInSession"];
}
if (Session["dynamicTabIDs"] != null)
{
//if dynamicTabIDs are in session, recreating the Tabs
//that are associated with the Tab IDs
//and adding them to the TabContainer that will contain
//all of the dynamic tabs.
//retrieving the tab IDs from session:
dynamicTabIDs = (List<string>)Session["dynamicTabIDs"];
if (TabContainerContent.ActiveTabIndex == -1)
{
TabContainerContent.ActiveTabIndex = Convert.ToInt16(Session["intTabIndex"]);
}
CreateDataSkeletton(Convert.ToInt16(Session["intTabIndex"]));
//looping through each TabID in session
//and recreating the TabPanel that is associated with that tabID
foreach (string tabID in dynamicTabIDs)
{
//creating a new TabPanel that is associated with the TabID
AjaxControlToolkit.TabPanel tab = new AjaxControlToolkit.TabPanel();
//TabContainerContent.ActiveTabIndex = tab;
//Setting the ID property of the TabPanel
tab.ID = tabID;
//setting the TabPanel's HeaderText
tab.HeaderText = "Days " + (TabContainerContent.Tabs.Count + 1).ToString();
//creating a Label to add to the TabPanel...at this point you'll have to
//create whatever controls are required for the tab...
Label tabContent = new Label();
//Giving the Label an ID
tabContent.ID = "lbl_tab_" + TabContainerContent.Tabs.Count.ToString();
//Setting the Label's text
tabContent.Text = "Tab " + (TabContainerContent.Tabs.Count + 1).ToString();
//Adding the Label to the TabPanel
tab.Controls.Add(tabContent);
//Adding the TabPanel to the TabContainer that contains the dynamic tabs
TabContainerContent.Tabs.Add(tab);
}
}
else
{ //Creating a new list of dynamicTabIDs because one doesn't exist yet in session.
dynamicTabIDs = new List<string>();
}
}
protected void Page_Load(object sender, EventArgs e)
{
}

Read Page Life Cycle
And you will get, that if you want to bind in code-behind, you should do it in Init Event, other wise there are no events will fire.

It seems to be Page.IsPostback problem.Need to add Page.IsPostback property in your page_load like
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
// Put your code inside that.
}
}
Actually your control is getting new value but when you click for updation then it calls old value from page_load.So try to put Page.IsPostback into your page_load event,Just like i mentioned.
I hope it helps.

UserControl Click event not firing

Hi this is my aspx page loading some values to the user control
protected void Page_Load(object sender, EventArgs e)
{
}
this is the usercontrol where i am loading and sending the values in find click event
protected void BtnFind_Click(object sender, EventArgs e)
{
Usr_BPOP BPOP = (Usr_BPOP)Page.LoadControl("~/Usr_BPOP.ascx");
BPOP.Date = txtDate.Text.Trim();
BPOP.DocNo = txtDocNo.Text.Trim();
BPOP.Code = txtCode.Text.Trim();
BPOP.Name = txtName.Text.Trim();
BPOP.Partcode = txtPartNo.Text.Trim();
if (chkReprint.Checked)
{
BPOP.BtnReprintVisible = true;
BPOP.BtnSaveVisible = false;
}
divControls.Controls.Clear();
PlaceHolder1.Controls.Add(BPOP);
}
this is my Usr_BPOP.ascx:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
btnReprint.Click += new EventHandler(btnReprint_Click);
}
btnReprint.Visible = false;
btnSave.Visible = BtnSaveVisible;
btnReprint.Visible = BtnReprintVisible;
if (btnReprint.Visible == false)
{
btnReprint.Text = "Print";
btnReprint.Visible = true;
}
table = new DataTable();
table.Columns.Add("DocNum", typeof(string));
table.Columns.Add("DocEntry", typeof(string));
table.Columns.Add("LineNum", typeof(string));
table.Columns.Add("PartNo", typeof(string));
table.Columns.Add("ItemDesc", typeof(string));
table.Columns.Add("QTR", typeof(string));
table.Columns.Add("QTP", typeof(string));
table.Columns.Add("Chk", typeof(bool));
table.Columns.Add("BarCode", typeof(string));
Datalayer dl = new Datalayer();
DataTable dttable = new DataTable();
if (!BtnSaveVisible && BtnReprintVisible)
BtnSaveVisible = true;
dttable = dl.GetPOItem(date, docNo, code, name, partcode, BtnReprintVisible, !BtnSaveVisible).Tables[0];
foreach (DataRow dr in dttable.Rows)
{
table.Rows.Add(dr["DocNum"].ToString(), dr["DocEntry"].ToString(), dr["LineNum"].ToString(), dr["PartNo"].ToString(),
dr["ItemDesc"].ToString(), dr["QTR"].ToString(), dr["QTP"].ToString(), Convert.ToBoolean(dr["Chk"]), dr["Barcode"].ToString());
}
if (table != null && table.Rows.Count > 0)
{
grdlistofitems.DataSource = table;
Session["Table"] = table;
grdlistofitems.DataBind();
}
else
{
}
}
this is the reprint button click event when i cilck this event it is not firing:
void btnReprint_Click(object sender, EventArgs e)
{
}

Since you are not setting the ID of the control, it is generated anew every time the control added to the page. The generated ID might not be the same, and therefore the sender of the event cannot be recognized. So first thing you should do is assign an ID explicitly:
Usr_BPOP BPOP = (Usr_BPOP)Page.LoadControl("~/Usr_BPOP.ascx");
BPOP.ID = "SomeID";
Secondly, assignment of the event handler should be done very time the control is created - that is, on every request, does not matter whether this is a postback or not - otherwise ASP.NET will not be able to determine what method should be called when the event is fired:
protected void Page_Load(object sender, EventArgs e)
{
// No check for postback here
btnReprint.Click += new EventHandler(btnReprint_Click);
Update. There is one more reason why this code does not behave as expected. The BPOP control is added to the page only on btnFind click. When the postback is caused by anything else, including btnReprint, on the response page generation BPOP control is not added to the page at all. If there is no control on the page - obviously its methods, including event handlers, cannot be triggered.
Here is quick and dirty fix for this situation. It should be applied to the page code where BPOP control is added:
protected void Page_Load(object sender, EventArgs e)
{
bool? addBPOP = ViewState["AddBPOP"] as bool?;
if (addBPOP.HasValue && addBPOP.Value)
{
AddBPOP();
}
}
protected void BtnFind_Click(object sender, EventArgs e)
{
AddBPOP();
ViewState["AddBPOP"] = true;
}
protected void AddBPOP()
{
Usr_BPOP BPOP = (Usr_BPOP)Page.LoadControl("~/Usr_BPOP.ascx");
BPOP.ID = "BPOPID";
BPOP.Date = txtDate.Text.Trim();
BPOP.DocNo = txtDocNo.Text.Trim();
BPOP.Code = txtCode.Text.Trim();
BPOP.Name = txtName.Text.Trim();
BPOP.Partcode = txtPartNo.Text.Trim();
if (chkReprint.Checked)
{
BPOP.BtnReprintVisible = true;
BPOP.BtnSaveVisible = false;
}
divControls.Controls.Clear();
PlaceHolder1.Controls.Add(BPOP);
}

Change:
void btnReprint_Click(object sender, EventArgs e)
{
}
To
protected void btnReprint_Click(object sender, EventArgs e)
{
}

Retrieving values of dynamically created controls on Post back in Asp.Net

I need to dynamically add CheckBoxList on the SelectedIndexChanged event of DropDownList. I have achieved this but I cannot retain its value on postback.
Here’s what I have done so far:
protected override void OnInit(EventArgs e)
{
base.OnInit(e);
loadTracks();//Needs to generated dynamically
}
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
loadDegrees();
}
loadTracks();
}
public void loadTracks()
{
try
{
ConfigurationDB objConfig = new ConfigurationDB();
DataSet ds = objConfig.GetTracksByDegreeID(
Convert.ToInt32(ddlDegree.SelectedValue.ToString()));
CheckBoxList CbxList = new CheckBoxList();
CbxList.ID = "Cbx";
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
{
CbxList.Items.Add(new ListItem(ds.Tables[0].Rows[i]["Track_Name"]
.ToString(), ds.Tables[0].Rows[i]["ID"].ToString()));
}
ph.Controls.Add(CbxList);
ViewState["tracks"] = true;
}
catch(Exception ex)
{
Response.Write(ex.Message);
}
}
//For testing, I added a button and on its click I have added this code
protected void btnDetails_Click(object sender, EventArgs e)
{
CheckBoxList Cbx = (CheckBoxList)ph.FindControl("chk");
foreach (ListItem ex in Cbx.Items)
{
if (ex.Selected)
{
Response.Write(String.Format("You selected: <i>{0}</i> <br>", ex.Value));
}
}
}

Might be a typo:
CbxList.ID = "Cbx";
v.s.
CheckBoxList Cbx = (CheckBoxList)ph.FindControl("chk");

You can try it without changing the code and use pre PreRender
just run you loadTracks()