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I am working on an ASP.NET VB.NET web form - a reservation web application, in which only one aspx page and rest are user-control page.
At run-time of aspx page, user controls load as per step and name define in db, like in below link.
ASP.NET Custom user control to add dynamically
In the first step, the first user-control is bind in page-init which is used to shows reservation availability detail in .NET datalist control like (see images).
All the details are bind to generate run-time control via data-list's item_databound event.
Now issue is whenever any event of datalist(click on romm-image or dropdown selected index changed) fired, the dynamic control remove like ammenities, dynamic dropdown of other row etc.
What I tried as :- ispostback, relevant event of page-life cycle, ajax-jquery, viewstate.
I checked this also, But no luck. : Dynamically added controls in Asp.Net
I analyze that, the user-control is always rebound and then event fired, but no datalist rebind and thus no - databound event fire and finally dynamic control is removed. If you wish, I will share the code too (but its huge code).
So question is how to retain the dynamic controls and its value when dropdown selected index changed or image click event fired in datalist in usercontrol?
I am not used update-panel, does that work? If yes, then please give sample data.
Good to answer with sample data. Even please suggest that if possible via any other control like grid-view or else, then I ready to change it.
Updated This is my code
Load User Control code In aspx page, usercontrol define to load another user control as per current step. This “uc” user control tag in aspx page.
<div id="divPlaceholder" runat="server">
<uc:DynamicControlHost ID="ucDynamicControlHost" runat="server" />
</div>
In page_load as well as page_prerender( ispostback ) , the below code execute to load runtime user-control.
public Control SetUserControlPath(string path)
{
Control c = null;
if (this.dynamicAllContent.Controls.Count > 0)
{
//Check that the new control is not the same as the current control
if (!this.UserControlPath.Equals(path))
{
//Remove the old item because we can not simply replace them!
this.dynamicPHAllContent.Controls.Clear();
c = Page.LoadControl(path + ".ascx");
c.ID = path;
//Add New Item
this.dynamicAllContent.Controls.Add(c);
lock (_userControlLockObject)
{
//Store the new path
_strUserControl = path;
}
}
}
else
{
c = Page.LoadControl(path + ".ascx");
c.ID = path;
this.dynamicAllContent.Controls.Add(c);
_strUserControl = path;
}
return c;
}
Structure of datalist in usercontrol
<asp:UpdatePanel ID="EmployeesUpdatePanel" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:DataList ID="dlLodgingAvailableDetails" ShowHeader="true" OnSelectedIndexChanged="dlLodgingAvailableDetails_SelectedIndexChanged" runat="server" CellPadding="2" CellSpacing="2" BorderWidth="1px" BorderColor="Black"
OnItemDataBound="dlLodgingAvailableDetails_ItemDataBound" BorderStyle="Solid" GridLines="Horizontal" HorizontalAlign="Justify">
<HeaderStyle CssClass="submit_butt"></HeaderStyle>
<HeaderTemplate>
Lodging Item Type Details
<asp:Button ID="btnBookRoom" runat="server" Text="Book Rooms" CssClass="submit_butt" OnClick="btnBookRoom_Click" />
</HeaderTemplate>
<ItemTemplate>
<table cellpadding="2" cellspacing="0" border="1" style="width: 100%";>
<tr>
<td style="width:170px">
<asp:ImageButton ID="imgLodging" OnClick="imgLodging_Click" commandargument='<%# Eval("ItemTypeId") %>'
runat="server" ImageUrl='<%# Eval("Photo") %>' Width="150px" Height="120px" />
</td>
<td style="width:180px">
<b>Name</b><br />
<span><%# Eval("ItemTypeName") %></span><br />
<b>Occupancy</b> <span><%# Eval("Occupancy") %></span>
<br />
<asp:panel ID="placeholderAmmenities" runat="server" Visible="True" ></asp:panel>
</td>
<td style="width:100px">
<b>Room</b><br />
<asp:hiddenfield runat="server" ID="hdnItemTypeId" Value='<%# Eval("LodgingItemTypeId") %>' />
<asp:DropDownList ID="ddlAvailable" runat="server"
AppendDataBoundItems="True" SelectedValue='<%# Bind("LodgingReservationsAvailable") %>' >
<asp:ListItem Value="0" Text="0"/>
<asp:ListItem Value="1" Text="1"/>
<asp:ListItem Value="2" Text="2"/>
</asp:DropDownList>
</td>
<td>
</td>
<td style="width:100px">
<div id="dvadult" runat="server"></div>
<asp:placeholder runat="server" ID="PlaceHolderAdult" ViewStateMode="Enabled" EnableTheming="False" Visible="True" ></asp:placeholder>
</td>
<td style="width:50px">
<asp:Label runat="server" ID="lblnumbernight" ></asp:Label>
</td>
<td style="width:50px">
<asp:placeholder ID="placeholderPrice" runat="server" Visible="True"></asp:placeholder>
</td>
<td style="width:50px">
<b>Total</b><br />
<asp:Label runat="server" ID="lblTotalAmount" ></asp:Label>
</td>
<td style="width:100px">
<asp:Button ID="btnBookRoom" runat="server" Text="Book Rooms" CssClass="submit_butt" />
</td>
</tr>
</table>
</ItemTemplate>
<SeparatorStyle BackColor="Lime" Font-Bold="False" Font-Italic="False" Font-Overline="False" Font-Strikeout="False" Font-Underline="False" HorizontalAlign="Center" />
</asp:DataList>
</ContentTemplate>
</asp:UpdatePanel>
Datalist item data bound event code (its inside image binding , price related field add and also creating the dynamic control as per the condition)
protected void dlLodgingAvailableDetails_ItemDataBound(object sender, DataListItemEventArgs e)
{
try
{
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
{
Image img = e.Item.FindControl("imgLodging") as Image;
if (img != null)
{
string bytesval = ((System.Data.DataRowView)(e.Item.DataItem)).Row.ItemArray[3].ToString();
if (string.IsNullOrWhiteSpace(bytesval)) return;
byte[] bytes = (byte[])((System.Data.DataRowView)(e.Item.DataItem)).Row.ItemArray[3];
string base64String = Convert.ToBase64String(bytes, 0, bytes.Length);
img.ImageUrl = "data:image/png;base64," + base64String;
}
DropDownList ddlList = e.Item.FindControl("ddlAvailable") as DropDownList;
Label lbldipositamount = e.Item.FindControl("lblTotalAmount") as Label;
Label lblnumbernight = e.Item.FindControl("lblnumbernight") as Label;
var PlaceHolderAmmenities = e.Item.FindControl("placeholderAmmenities") as Panel;
ddlList.Attributes.Add("onchange", " openLodgingNumber1(this,'" + ddlList.SelectedValue + "');");
int? LodgingItemTypeId = Convert.ToInt32(((System.Data.DataRowView)(e.Item.DataItem)).Row.ItemArray[1]);
DataSet ds = new DataSet();
ds = LodgingData.SelectLodgingItemTypeAmenityDateSet(LodgingItemTypeId);
DataTable dt = new DataTable();
if (ds != null)
{
dt = ds.Tables[0];
if (dt.Rows.Count > 0)
{
for (int j = 0; j < dt.Rows.Count; j++)
{
Image image = new Image();
image.ID = "imgAmmenities" + j + DateTime.Now.ToString();
string bytesval = dt.Rows[j]["AmenityIcon"].ToString(); //((System.Data.DataRowView)(e.Item.DataItem)).Row.ItemArray[4].ToStrin();
//if (string.IsNullOrWhiteSpace(bytesval)) return;
if (bytesval != string.Empty)
{
byte[] bytes = (byte[])dt.Rows[j]["AmenityIcon"];
string base64String = Convert.ToBase64String(bytes, 0, bytes.Length);
image.ImageUrl = "data:image/png;base64," + base64String;
image.Height = 20;
image.Width = 20;
image.EnableViewState = true;
PlaceHolderAmmenities.Controls.Add(image);
PlaceHolderAmmenities.Controls.Add(new LiteralControl(" "));
}
}
}
}
decimal PriceTotal = 0;
var PlaceHolderPrice = e.Item.FindControl("placeholderPrice") as PlaceHolder;
DataSet dsprice = new DataSet();
dsprice = LodgingData.SelectLodgingItemTypePrice(LodgingItemTypeId);
if (dsprice != null)
{
DataTable dtprice = new DataTable();
dtprice = dsprice.Tables[0];
if (dtprice.Rows.Count > 0)
{
DateTime fromdate = Convert.ToDateTime(txtFromDate.Text);
DateTime todate = Convert.ToDateTime(txtToDate.Text);
double daterange = ((todate - fromdate).TotalDays + 1);
lblnumbernight.Text = daterange.ToString();
//for (DateTime date = fromdate; date >= todate; date.AddDays(1))
for (int d = 0; d < Convert.ToInt32(daterange); d++ )
{
DateTime date = fromdate.AddDays(d);
//DataView dv = new DataView(dtprice);
DataTable dtprice1 = new DataTable();
DataRow[] rows = dtprice.Select("#" + date + "# >= PriceStartDate AND" + "#" + date + "# <= PriceEndDate");
if (rows.Length > 0)
{
dtprice1 = rows.CopyToDataTable();
}
if (dtprice1.Rows.Count > 0)
{
for (int j = 0; j < dtprice1.Rows.Count; j++)
{
Label lbl = new Label();
string dayofweek = dtprice1.Rows[j]["DayOfWeekId"].ToString();
if (dayofweek.Trim() == eDayOfWeek.All.ToString().Trim())
{
lbl.ID = "lbl" + j;
lbl.Text = dtprice1.Rows[j]["Price"].ToString();
PriceTotal += Convert.ToDecimal(dtprice1.Rows[j]["Price"]);
PlaceHolderPrice.Controls.Add(lbl);
PlaceHolderPrice.Controls.Add(new LiteralControl("<br />"));
}
else if (Convert.ToInt32(dayofweek) == Convert.ToInt32(date.DayOfWeek + 1))
{
lbl.ID = "lbl" + j;
lbl.Text = dtprice1.Rows[j]["Price"].ToString();
PriceTotal += Convert.ToDecimal(dtprice1.Rows[j]["Price"]);
PlaceHolderPrice.Controls.Add(lbl);
PlaceHolderPrice.Controls.Add(new LiteralControl("<br />"));
}
}
}
else
{
DataView dv1 = new DataView(dtprice);
dv1.RowFilter = "PriceStartDate IS NULL OR PriceEndDate IS NULL";
//dv1.RowFilter = "PriceStartDate == null and PriceEndDate == null";
DataTable dtprice2 = new DataTable();
dtprice2 = dv1.ToTable();
for (int j = 0; j < dtprice2.Rows.Count; j++)
{
Label lbl = new Label();
string dayofweek = dtprice2.Rows[j]["DayOfWeekId"].ToString();
if (dayofweek.Trim() == eDayOfWeek.All.ToString().Trim())
{
lbl.ID = "lbl" + j;
lbl.Text = dtprice2.Rows[j]["Price"].ToString();
PriceTotal += Convert.ToDecimal(dtprice2.Rows[j]["Price"]);
PlaceHolderPrice.Controls.Add(lbl);
PlaceHolderPrice.Controls.Add(new LiteralControl("<br />"));
}
else if (Convert.ToInt32(dayofweek) == Convert.ToInt32(date.DayOfWeek + 1))
{
lbl.ID = "lbl" + j;
lbl.Text = dtprice2.Rows[j]["Price"].ToString();
PriceTotal += Convert.ToDecimal(dtprice2.Rows[j]["Price"]);
PlaceHolderPrice.Controls.Add(lbl);
PlaceHolderPrice.Controls.Add(new LiteralControl("<br />"));
}
}
}
}
}
}
lbldipositamount.Text = PriceTotal.ToString();
// var amount = ((System.Data.DataRowView)(e.Item.DataItem)).Row.ItemArray[3];
int selectedvalue = Convert.ToInt32(ddlList.SelectedItem.Text);
if (selectedvalue != 0)
{
double totalamount = selectedvalue * Convert.ToDouble(PriceTotal);
lbldipositamount.Text = totalamount.ToString();
}
}
}
catch (Exception)
{
throw;
}
}
On dynamically genereted dropdown selection event fired
In above even add this dropdown dynamically, now when this control's event is called , further dynamic control is adding as per the condition.
Issue is this event remove the dynamic other control as well even for other row of the previous selection is hidden or lost , so we retain the dynamic control in any post back and event fire.
protected void ddlAvailable_SelectedIndexChanged(object sender, EventArgs e)
{
// if (UserControlTextBoxChanged != null) dlLodgingAvailableDetails_ItemDataBound(sender, e);
//dlLodgingAvailableDetails.ItemDataBound += new DataListItemEventHandler(dlLodgingAvailableDetails_ItemDataBound);
double amount = 0;
var ddlList = (DropDownList)sender;
var row = (DataListItem)ddlList.NamingContainer;
//get the Id of the row
DataSet ds = new DataSet();
int? Id = Convert.ToInt32(((HiddenField)row.FindControl("hdnItemTypeId")).Value);
double? tamount = Convert.ToDouble(((Label)row.FindControl("lblTotalAmount")).Text);
int? groupid = Convert.ToInt32(ddlLodgingGroup.SelectedValue);
int selectedvalue = Convert.ToInt32(ddlList.SelectedItem.Text);
DateTime? startdate = Convert.ToDateTime(txtFromDate.Text);
DateTime? enddate = Convert.ToDateTime(txtToDate.Text);
ds = LodgingData.SelectLodgingItemTypeDataSet(startdate, enddate, groupid);
DataTable dt = new DataTable();
DataView dv = new DataView();
if (ds != null)
{
dt = ds.Tables[0];
dv = dt.DefaultView;
dv.RowFilter = "LodgingItemTypeId=" + Id;
}
dt = dv.ToTable();
if (dt.Rows.Count > 0)
{
if (tamount != null)
{
amount = Convert.ToDouble(tamount);
}
}
//amount = Convert.ToDouble(((Label)row.FindControl("lblTotalAmount")).Text);
var PlaceHolder1 = ((PlaceHolder)row.FindControl("PlaceHolderAdult"));
double totalamount = 0;
if (selectedvalue != 0)
{
totalamount = selectedvalue * Convert.ToDouble(amount);
((Label)row.FindControl("lblTotalAmount")).Text = totalamount.ToString();
Label lblAdult = new Label();
lblAdult.ID = "lblAdult";
lblAdult.Text = "Adult";
lblAdult.Font.Bold = true;
PlaceHolder1.Controls.Add(lblAdult);
PlaceHolder1.Controls.Add(new LiteralControl("<br />"));
}
else
{
totalamount = amount;
}
for (int j = 0; j < selectedvalue; j++)
{
DropDownList ComboBox = new DropDownList();
ComboBox.ID = "ComboBox" + j;
ComboBox.AutoPostBack = false;
ComboBox.Attributes.Add("runat", "server");
ComboBox.Items.Add(new ListItem("0", "0"));
ComboBox.Items.Add(new ListItem("1", "1"));
ComboBox.Items.Add(new ListItem("2", "2"));
ComboBox.SelectedIndexChanged += new EventHandler(Dynamic_Method);
PlaceHolder1.Controls.Add(ComboBox);
PlaceHolder1.Controls.Add(new LiteralControl("<br />"));
}
}
886
I'm not sure how much this will solve for you, but here is an example of preserving a row of data in a gridview with a templatefield containing a dynamically generated dropdownlist
I broke the process into 2 parts 1) Save data currently in Gridview to a session variable 2) Recreate, source, and bind controls
Here's saving the values in the gridview. I use a recursive find control formula I found on this site (but don't remember from where) because my controls are generated and placed inside the gridview row without unique names. For ex. the tbxA that exists in row 1 is different than the tbxA in row 2. This may not apply to you - the key is to find all controls you want to save the values of.
Private Sub SaveValues()
Dim savedTable As New DataTable
savedTable.Columns.Add(New DataColumn("A"))
For i = 0 To GridView1.Rows.Count - 1
Dim existing(0) As Object
existing(0) = TryCast(FindControlRecursive(GridView1.Rows(i), "ddlA"), DropDownList).SelectedValue
savedTable.Rows.Add(existing)
Next
Session("GhostTable") = savedTable
End Sub
Then in Page_Load under(when it IS a postback) set the gridview datasource to the session variable, and databind it. This will trigger the following code for every row: Keep in mind I also have the datasource of the dropdown list stored in a session variable on page load. This allows the datasource and databind to occur for the dropdown every time it is generated.
Protected Sub OnRowDataBound(sender As Object, e As GridViewRowEventArgs) Handles GridView1.RowDataBound
'Handles databinding of each gridview1 row ddl to gridview templatefield
If e.Row.RowType = DataControlRowType.DataRow Then
Dim ddlA As New DropDownList()
ddlA.DataSource = Session("lengthList")
ddlA.DataBind()
ddlA.ID = "ddlA"
ddlA.SelectedValue = TryCast(e.Row.DataItem, DataRowView).Row.Item("A").ToString()
e.Row.Cells(1).Controls.Add(ddlA)
End if
End Sub
The ddlA.SelectedValue = TryCast(e.Row.DataItem, DataRowView).Row.Item("A").ToString() is what preserves the data after any postback. It determines which row is being bound, and then repopulates the control with whatever it previously was.
Hope this helps!
To make sure that the gridview is populated every time, call SaveValues in your event handlers.
Protected Sub ddlEmpNumber_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ddlEmpNumber.SelectedIndexChanged
'Do whatever on selected index change, then the following:
Call SaveValues()
GridView1.DataSource = Session("GhostTable")
GridView1.DataBind()
End Sub
You're wiring up the eventhandler in the ASP part like this:
<asp:DataList ID ... OnSelectedIndexChanged="dlLodgingAvailableDetails_SelectedIndexChanged" ...
and then in code of the handler attempting to re-wire the other ones:
ComboBox.SelectedIndexChanged += new EventHandler(Dynamic_Method);
Any time you do dynamic stuff on a webforms page, all setup including event handler wireup must be in the page_init. When events run, re-wiring won't work. For what you're doing (asp: ... and during a method call), it's ending up in the wrong part of the lifecycle and the right things aren't there to either add the javascript to call doPostback, or if that runs the __eventargs, etc. have data for controls that aren't built yet (event postbacks are checked for AFTER page init so you have to create the controls before that check) and therefore get ignored.
Note - probably you know this but you have to give controls unique IDs, generally can by done if you have a numeric primary key by just appending to the datarows. (might have to do this manually to child controls in user control, have had to do this with usercontrols in page_init, hopefully you won't)
I work on a big app that dynamically builds every screen in webforms (from a UI generator) in the page-init. All work is done in events, they work like a charm! Page_load is basically empty. Get to know the asp page lifecycle - it's a booger but easier than rewriting your app in HotTowel (although think about that the next app ;-)
Pretty good diagram: http://blogs.msdn.com/b/aspnetue/archive/2010/01/14/asp-net-page-life-cycle-diagram.aspx
Good luck!
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