使用C＃在数据列表中的SelectedIndexChanged事件上获取RadioButtonList的SelectedValue

Question

I've created a DataList in which there are 2 Label and a RadioButtonList . The 2 Label contains question ID and the question in which the Question ID is hidden, and the RadioButtonList contains the options. All these controls are bounded. Here's the code:

<asp:DataList ID="DataList1" runat="server">
    <ItemTemplate>
        <asp:Label ID="Que_id" Visible="false" runat="server" Text='<%# Eval("question_id") %>'></asp:Label>
        <asp:Label ID="Question" runat="server" Text='<%# Eval("question") %>'></asp:Label>
        <asp:RadioButtonList ID="RadioButtonList1" AutoPostBack="true" RepeatColumns="2" runat="server" OnSelectedIndexChanged="RadioButtonList1_SelectedIndexChanged">
        </asp:RadioButtonList>
    </ItemTemplate>
</asp:DataList>

What I'm trying to do is whenever user selects an option in the RadioButtonList the selected option and its question id should get stored in the database. It's easy to store the whole DataList at the button click event, but I want to store the response side by side as the user selects the option for a particular question.

I don't know how to get the question ID on SelectedIndexChanged event but I tried the following code on SelectedIndexChanged to get the selected option value but this too doesn't work.

RadioButtonList rbl = (RadioButtonList)DataList1.FindControl("RadioButtonList1");
string answer=rbl.SelectedValue;

For more clarification, I brought this data from database in a DataSet and filtered it for the question ID, question and options. The values are being set during the Page_Load in the if(!IsPostBack).

Answer 1

Try below,

modify

<asp:DataList ID="DataList1" runat="server">

To

<asp:DataList ID="DataList1" OnItemCommand="DataList1_command" runat="server">

Assuming you have a <asp:Button and id as button1 and OnClick as bclick

void bclick(object sender, DataListCommandEventArgs e)
    {
        foreach (DataListItem item in DataList1.Items)
        {
            HtmlInputRadioButton radio = (item.FindControl("radioButton") as HtmlInputRadioButton);
            if (radio.Checked)
            {
                // this is you checked radio
            }
        }
    }

Answer 2

You can use a HiddenField to store the question ID in the DataList (it is more "natural" than an invisible Label):

<asp:HiddenField ID="hiddenQuestionID" runat="server" Value='<%# Eval("question_id") %>' />

In the event handler of the RadioButtonList, you can use the sender parameter to retrieve the control, and then get the selected value. The NamingContainer of the RadioButtonList also contains the HiddenField, from which you can get the question ID:

protected void RadioButtonList1_SelectedIndexChanged(object sender, EventArgs e)
{
    RadioButtonList rbl = sender as RadioButtonList;
    string answer = rbl.SelectedValue;
    HiddenField hiddenQuestionID = rbl.NamingContainer.FindControl("hiddenQuestionID") as HiddenField;
    string questionID = hiddenQuestionID.Value;
    ...
}