I got a weird problem. I use a DropDownList item in a web application. after i check for the first time one of the options all the items are added to end of the list.
initialized like this
protected void Page_Load(object sender, EventArgs e)
{
string myXMLfile = Server.MapPath("~/VMlist.xml");
DataSet dsMachines = new DataSet();
try
{
dsMachines.ReadXml(myXMLfile);
DropDownList1.DataSource = dsMachines;
DropDownList1.DataValueField = "machineID";
DropDownList1.DataTextField = "machineName";
DropDownList1.DataBind();
}
catch (Exception ex)
{
Response.Write(ex.ToString());
}
}
and the SelectedIndexChanged:
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
machineOS.Text = OSdata.OSDataRetrieve.getOSInfo(DropDownList1.SelectedItem.Text);
}
i use XML initializing. I'm also adding an image of 'before' and 'after'
You need to add the following to your Page_Load:
if (!Page.IsPostBack)
{
//code to bind dropdown
}
Your list is being bound each time the page posts back, which is why you're getting duplicates. Add the above line, and you should be all set.
Because you had set the AppendDataBoundItems="true"
You have to set it to AppendDataBoundItems="false"
Every time the dropdown selected Index changed event is fired, your dropdownlist again binded and added datasource items again.
In page_load, you should probably check for IsPostback.
Currently, you are rebinding the list to the listbox on each load. It's not just adding 3 new items - there is a scrollbar and I suspect it is re-adding ALL of the items.
My problem was that I manually called databind() but found that databind was already being called during because it was a nested databound control. Try commenting out your databind call and see if that fixes it.
Related
I have a dropdownlist on a webform that I fill from a sql query, I then want to be able to select individual items in the dropdown and have corresponding fields from a datatable fill textboxes on the form
Problem is rowSel is returning 0 and the dropdown won't let me select any other item it always snaps back to the first itenm in the list.
Thought this might have something to do with autopostback being set to true, but if I set it to false that causes otheer problems, Not sure what else to try Im a winforms person and very new to asp.net
protected void ddClients_SelectedIndexChanged(object sender, EventArgs e)
{
int rowSel = ddClients.SelectedIndex;
txtClient.Text = dsShow.Rows[rowSel["ClientsTableFieldA"].ToString();
}
It should allow me to select a value from the drop down then populate some textboxes with fields from the datatable.
You could try:
protected void ddClients_SelectedIndexChanged(object sender, EventArgs e)
{
txtClient.Text = ddClients.SelectedItem.Value.ToString();
}
protected void ddClients_SelectedIndexChanged(object sender, EventArgs e)
{
txtClient.Text = ddClients.SelectedItem.Text;
}
As suggested by B. Seberle
DDL items have fields value and text so it depends how you bound the ddl to SQL datasource.
place break point on txtClient.Text = ddClients.SelectedItem.Text see if item list is empty.
it should not be necessary but you can force a ddClient.databind() in page_load if(!Page.IsPostback).
however ddClients_SelectedIndexChanged will only trigger on postback.
I have a radcombobox,I want get checked items and save it in database but when i click save button,page is load again and my radcombobox become empty and then all of my checked items disappear.please help me,how can keep ckeckeditems?
As D Stanley mentioned in the comments, you're probably not checking for a postback when populating your dropdown.
This is the general approach you need to use in your code...
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
PopulateTheDropdown();
}
}
private void PopulateTheDropdown()
{
// Populate / databind your dropdown here
}
This will ensure your dropdown is not rebound when a postback occurs so you don't lose the selected value(s).
If you have autopostback activated you must save the selected value separately. Try to explicitly disable and check the value when the event fires:
<telerik:RadComboBox ID="RadComboBoxControl" AutoPostBack="false" OnSelectedIndexChanged="RadComboBoxControl_SelectedIndexChanged" runat="server" EmptyMessage="Select something"></telerik:RadComboBox>
protected void RadComboBoxControl_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
{
// Only test
var seleccionado = RadComboBoxControl.Items.FindItemByText(e.Text);
}
Check if you have assigned DataSource of the control in other parts of the code
RadComboBoxControl.DataSource = ...
RadComboBoxControl.DataBind();
This will also lose the selected element
In the following code everytime its taking only one item from dropdownlist. When I select any other item from dropdownlist its same as first item.
Please give solution
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
DataSet _subcat = new DataSet();
_subcat = serviceus.Get_SERVICEUS_SUB_CATEGORYLIST(DropDownList1.SelectedValue.ToString());
lbsubcategory.DataSource = _subcat.Tables[0].DefaultView;
lbsubcategory.DataTextField = Convert.ToString(_subcat.Tables[0].Columns["CATEGORY_SUB1_NAME"].ColumnName);
lbsubcategory.DataBind();
Label5.Visible = true;
}
Check how you bind your dropdownlist. I think you're binding it everytime your page posts back to server. Try to use IsPostBack property of the page :
if (!IsPostBack){
DropDownList1.DataSource = datasource;
DropDownList1.DataBind();
}
Do you have:
if(!IsPostBack) {
DataBind();
}
around your initial databind (eg in OnLoad)
EnableViewState="False" on the lbsubcategory.
Assuming AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged"
I have one asp.net application, in which i have one dropdown which is binded to dataset. But after selecting one item, the drop down gets cleared all the value, How we can resolve this issue?
This is my dropdown list in design page:
<asp:DropDownList ID="ddlProduct" runat="server" CssClass="textEntry" Width="300px"
AutoPostBack="True" OnSelectedIndexChanged="ddlProduct_SelectedIndexChanged">
</asp:DropDownList>
and binding code is shown below.
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
BindProductDdl();
}
private void BindProductDdl()
{
Products objProducts = new Products();
dsProducts dsProduct = new dsProducts();
ListItem olst = default(ListItem);
olst = new ListItem(" Select", "0");
dsProduct = objProducts.GetDataset("");
ddlProduct.DataSource = dsProduct;
ddlProduct.DataTextField = "Product";
ddlProduct.DataValueField = "Id";
ddlProduct.DataBind();
ddlProduct.Items.Insert(0, olst);
}
protected void ddlProduct_SelectedIndexChanged(object sender, EventArgs e)
{
Products objProducts = new Products();
dsProducts dsProduct = new dsProducts();
string criteria = "";
if (ddlProduct.SelectedItem.Text != " Select")
{
string id = ddlProduct.SelectedItem.Value;
criteria = "Id='" + id + "'";
dsProduct = objProducts.GetDataset(criteria);
productValue = Convert.ToDecimal(dsProduct.tblProducts.Rows[0]["Value"].ToString());
}
}
Thanks in advance..
From your question if I understand correctly you dont want the dropdown list to rebind if it is populated. Also please check your viewstate, this should not be happening, unless you have disabled viewstate
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack && ddlProduct.Items.count <=0 )
BindProductDdl();
}
Set the AppendDataBoundItems property of the dropdown to true and this will allow you to have a mix of databound items and non databound items (otherwise that insert statement is clearing your list)
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.listcontrol.appenddatabounditems.aspx
Do you have viewstate disabled on the page? Since you are only loading the items into the dropdownlist on the first load of the page, if viewstate is not enabled there will be nothing in the list after the postback.
Not positive, but I've seen in other languages and false interpretation...
You have your product Value as convert of ToDecimal which implies 99.999 for example.
If your ID that you are binding to is based on a whole number (ie: Integer basis), the bound value won't match... even if Value = 1 vs Value = 1.00 it won't match and will not be considered a valid "value" that matches your list. Convert your answer to a whole/integer number and it might do what you expect.
Without seeing the full source for the page I am simply speculating, but have you disabled ViewState on the page? If so, the DropDownList cannot retain its values between postbacks and the lists will have to be reloaded each time.
(Scroll down to bottom of post to find solution.)
Got a asp.net page which contains a
Datalist. Inside this datalist, there
is a template containing a
dropdownlist and each time the
datalist is filled with an item, a
ItemCreatedCommand is called. The
itemCreatedCommand is responsible for
databinding the dropdownlist.
I think the problem lies here, that
I'm using ItemCreatedCommand to
populate it - but the strange things
is that if I choose the color "green",
the page will autopostback, and I will
see that the dropdown is still on the
color green, but when trying to use
it's SelectedIndex, I always get 0...
protected void DataListProducts_ItemCreatedCommand(object
source, DataListItemEventArgs e)
var itemId = (String)DataListProducts.DataKeys[e.Item.ItemIndex];
var item = itemBLL.GetFullItem(itemId);
var DropDownListColor = (DropDownList)e.Item.FindControl("DropDownListColor");
//Also tried with :
//if(!isPostBack) {
DropDownListColor.DataSource = item.ColorList;
DropDownList.Color.Databind();
// } End !isPostBack)
Label1.test = DropDownListColor.SelectedIndex.toString();
// <- THIS IS ALWAYS 0! *grr*
I've narrowed down the code a bit for
viewing, but still you can see what
I'm trying to do :) The reason for
why I'm doing this, and not declaring
the datasource for the colors directly
i aspx-page, is that I need to run a
test if(showColors), but I do not want
to clutter up the html-page with code
that I feel should be in the code
behind-file.
EDIT: After trying to alter
SelectedIndexChange - I'm having a
"logical" confusion in my head now -
how am I to alter elements inside the
datalist? Since, as far as I know - I
do not have any way to check which of
the items in the datalist this
particular dropdownlist belongs to...
Or? I'm going to try out a few ways
and see what I end up with ;) But do
please post your thoughts on this
question :)
SOLUTION:
Either bubble the event to ItemCommand, or Handle the event, get the senders parent(which is a datalistItem and manipulate elements in there.
protected void DropDownListColor_SelectedIndexChanged(object sender, EventArgs e)
{
DropDownList dropDownListColor = (DropDownList)sender;
DataListItem dataListItem = (DataListItem)dropDownListColor.Parent;
var item = items[dataListItem.ItemIndex];
var color = item.ItemColor[dropDownListColor.SelectedIndex];
var LabelPrice = (Label)dataListItem.FindControl("LabelPrice");
LabelPrice.Text = color.Price;
}
When the DataList is data-bound, the AutoPostBack has not been handled yet, i.e. the values in the ItemCreated event are still the original values.
You need to handle the SelectedIndexChange event of the dropdown control.
Regarding your 2nd question:
I suggest you remove the AutoPostBack from the dropdown, add an "Update" button, and update the data in the button Click event.
The button can hold Command and CommandArgument values, so it's easy to associate with a database record.
some MSDN links with C# examples on bubbling
http://msdn.microsoft.com/en-us/library/system.web.ui.control.onbubbleevent.aspx
http://msdn.microsoft.com/en-us/library/aa719644(VS.71).aspx
http://msdn.microsoft.com/en-us/library/aa720044(VS.71).aspx
Thank You for your solution
protected void ddlOnSelectedIndexChanged(object sender, EventArgs e) {
try {
ModalPopupExtender1.Show();
if (ViewState["Colors"] != null) {
FillColors(ViewState["Colors"].ToString());
}
DropDownList dropDownListColor = (DropDownList)sender;
DataListItem dataListItem = (DataListItem)dropDownListColor.Parent;
Image image = (Image)dataListItem.FindControl("mdlImage");
Label ProductCode = (Label)dataListItem.FindControl("lblprdCode");
Label ProductName = (Label)dataListItem.FindControl("lblProdName");
DropDownList ddlQuantity = (DropDownList)dataListItem.FindControl("ddlQuantity");
Label ProductPrice = (Label)dataListItem.FindControl("lblProdPrice");
Label TotalPrice = (Label)dataListItem.FindControl("lblTotPrice");
//Label ProductPrice = (Label)dataListItem.FindControl("lblProdPrice");
} catch (Exception ex) {
}
}