Develop Reference

Is there a way to make an item in a DropDownList not selectable?

I have an ASP.net dropdownlist with four items,
<asp:DropDownList ID="DropDownList1" runat="server">
<asp:ListItem Selected="True" Value="0">Select Payment Method</asp:ListItem>
<asp:ListItem>Credit Card</asp:ListItem>
<asp:ListItem>PayPal</asp:ListItem>
<asp:ListItem>WeKea Store Gift Card</asp:ListItem>
</asp:DropDownList>
Is there a way to make "Select Payment Method" not selectable? I read through all the properties of an ASP.net DDL and I dont see anything of the sort.

You can use the disabled attribute (see here) and apply it to the ListItem:
<asp:DropDownList ID="DropDownList1" runat="server">
<asp:ListItem Selected="True" Value="0" disabled="disabled">Select Payment Method</asp:ListItem>
<asp:ListItem>Credit Card</asp:ListItem>
<asp:ListItem>PayPal</asp:ListItem>
<asp:ListItem>WeKea Store Gift Card</asp:ListItem>
</asp:DropDownList>
This will render the option as greyed out and it will not be selectable. However, the selected=True will override that and it will be displayed as selected when the page loads, which I think is what you want.

stop autopost back on default value of dropdownlist asp.net

I have a dropdownlist(autopostback enabled) in my project in binded through sqldatasource, i have added an initial value to it using list item. The problem is the page is being postbacked even when selecting the initial value which i dont want. Is there a way to achieve this?
<asp:DropDownList ID="DropDownListTheme" runat="server"
DataSourceID="SqlDataSourceTheme" DataTextField="h_theme"
DataValueField="h_theme" Height="30px" Width="30%"
AppendDataBoundItems="true" AutoPostBack="True">
<asp:ListItem Text="--Select One--" Value="-1" />
</asp:DropDownList>

Set the initial item as selected initially
<asp:ListItem Text="--Select One--" Selected="True" Value="-1" />

Add
onchange="if(this.selectedIndex == 0)return false;"
event to drop down list.

asp dropdown reload page when setting dropdown.selectedvalue

I have the following asp dropdown:
<asp:DropDownList ID="ArticleCategories" runat="server" AppendDataBoundItems="true" CssClass="ArticleCategoriesDropDown" onselectedindexchanged="mCategoryItemSelected" AutoPostBack="True">
<asp:ListItem Text="Select Category" Value="" />
</asp:DropDownList>
Once a selection has been made, and the data loaded, I want to set the value in the dropdown to display the value chosen by the user.
I am doing this by:
ArticleCategories.SelectedValue = CategoryID.ToString();
This works fine the first time, but from then the page is stuck on that selection, as the selected value gets loaded before the new value can load.
I have tried disabling the itemchangelistener by:
ArticleCategories.SelectedIndexChanged += new EventHandler(doNothing);
But that does not work.
I have also tried to disable postback which also does not work.
Any ideas?

You should only set the selection when loading the page the first time. In ASP.NET, you can achieve this by checking the IsPostBack property:
if(!IsPostBack)
{
ArticleCategories.SelectedValue = CategoryID.ToString();
}

You can do Autopostback= false
<asp:DropDownList ID="ArticleCategories" runat="server" AppendDataBoundItems="true" CssClass="ArticleCategoriesDropDown" onselectedindexchanged="mCategoryItemSelected" AutoPostBack="False">
<asp:ListItem Text="Select Category" Value="" />
</asp:DropDownList>

Hey before selecting another item from Dropdown you should clear previous selection then selected another one.
ArticleCategories.ClearSelection();
Hope it helps you.

How to add the checkbox item at the new line?

I have a checkbox list like below:
<asp:CheckBoxList id="chx" runat="server" repeatdirection="Horizontal"> <asp:ListItem value="OPTION1">Option 1</asp:ListItem>
<asp:ListItem value="OPTION2">Option 2</asp:ListItem>
<asp:ListItem value="OPTION3">Option 3</asp:ListItem><
asp:ListItem value="OPTION4">Option 4</asp:ListItem>
</asp:CheckBoxList>
And I am dynamically adding the list items to this checkbox using the following C# code:
chx.Items.Clear();
while(dr.Read()){
if(dr.GetOracleString(0).ToString()!="Null"){
chx.Items.Add(dr.GetOracleString(0).ToString());
}
}
My requirement is whenever the new item is added in the checkboxlist, it should check whether the new item is going beyond the border(fixed width) of the page and if so the new item should go the next line of checkboxlist without overlapping below control.
Please help me to fix this.

You can use the property RepeatColumns
RepeatColumns="3"

affecting existing RadioButtonList to set a default value

I have an existing RadioButtonList on a page and need to set the second button to be checked as default instead of the first.
I probably need to do it with javascript on the page as I cannot edit the original control.
<list:RadioButtonList runat="server" Class="class" Text="text"
AlternativeText="alternative text" />
Any idea how i can detect the control and set its default value?

If you use ASP.NET you can set the following:
<asp:RadioButtonList ID="RadioButtonList1" runat="server">
<asp:ListItem Selected="True" ></asp:ListItem>
<asp:ListItem></asp:ListItem>
<asp:ListItem></asp:ListItem>
<asp:ListItem></asp:ListItem>
<asp:ListItem></asp:ListItem>
</asp:RadioButtonList>
I've added the attribute Selected="True", so you always have a default value selected.
You can also do this in code:
if (RadioButtonList1.SelectedIndex == -1) //-1 is the indication of none selected
{
RadioButtonList1.SelectedIndex = 2; //select index 2 (can also be value or text)
}