如何检索单选按钮列表的选定值

Question

I'm working on a random quiz generator for Sharepoint, and i'm stuck at a small issue, when checking if the selected answer matches the correct answer.

i have a radiobutton list declared global.

public static RadioButtonList[] RadioButtonList = new RadioButtonList[5]; //5 elements are enough, as i'll stick to a 5-question quiz for now.

Then, when populating the dropdown list, i'm creating a new object and adding the items (answers) to the list.

for (var i=0; ... )
...
RadioButtonList[i] = new RadioButtonList();                 
RadioButtonList[i].Items.Add(SPListItemCollection[index]["Column"].ToString());
...

Everything works fine till now. All the above happens in the click event for the button that generates the code.

My problem comes in the following event, made for the Compare button. I am trying to compare the selected radiobutton value with another value stored in a label, that represents the correct answer. The thing is, the following condition does not work:

for (var index ... )
....
if (RadioButtonList[index].SelectedValue.Equals(label_Response[index].Text))
...

The "RadioButtonList[index].SelectedValue" is always empty, and i get a NullReferenceException when debugging.

If anyone can help me solve this issue, or knows a better solution, i will be very grateful.

Thanks in advance, Calin.

Answer 1

This would work only if ALL the radiobuttons would be selected. You are going foreach radiobutton when only one can be selected at one time. Try checking for not null.

for (var index ... )
....
if (RadioButtonList[index].SelectedValue!=null &&  RadioButtonList[index].SelectedValue.Equals(label_Response[index].Text))
...

Another thing how can you be certain that label_Response[index] will match RadioButtonList[index] ? This is massive assumption IMHO.