Set Radiobuttonlist Selected from Codebehind

Hey I have a radiobuttonlist and trying to set one of the radiobuttons to selected based on a session variable but proving impossible.

<asp:radiobuttonlist id="radio1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="RadioButtonList1_SelectedIndexChanged">
   <asp:listitem id="option1" runat="server" value="All"/>
   <asp:listitem id="option2" runat="server" value="1" />
   <asp:listitem id="option3" runat="server" value="2" />
</asp:radiobuttonlist>

I.e How can I set option2 to selected in code behind ?

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

The best option, in my opinion, is to use the Value property for the ListItem, which is available in the RadioButtonList.

I must remark that ListItem does NOT have an ID property.

So, in your case, to select the second element (option2) that would be:

// SelectedValue expects a string
radio1.SelectedValue = "1";

Alternatively, yet in very much the same vein you may supply an int to SelectedIndex.

// SelectedIndex expects an int, and are identified in the same order as they are added to the List starting with 0.
radio1.SelectedIndex = 1;

Method 2

You could do:

radio1.SelectedIndex = 1;

But this is the most simple form and would most likely become problematic as your UI grows. Say, for instance, if a team member inserts an item in the RadioButtonList above option2 but doesn’t know we use magic numbers in code-behind to select – now the app selects the wrong index!

Maybe you want to look into using FindControl in order to determine the ListItem actually required, by name, and selecting appropriately. For instance:

//omitting possible null reference checks...
var wantedOption = radio1.FindControl("option2").Selected = true;

Method 3

Try this option:

radio1.Items.FindByValue("1").Selected = true;

Method 4

We can change the item by value, here is the trick:

radio1.ClearSelection();
radio1.Items.FindByValue("1").Selected = true;// 1 is the value of option2

Method 5

var rad_id = document.getElementById('<%=radio_btn_lst.ClientID %>');
var radio = rad_id.getElementsByTagName("input");
radio[0].checked = true;

//this for javascript in asp.net try this in .aspx page

// if you select other radiobutton increase [0] to [1] or [2] like this

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0