How to change Html.RadioButtonFor selection in MVC3? - asp.net-mvc

Question

My model has a list of 3 elements, each element has a string (AnswerBody) and a bool (correct).
When I submit the form, I get the values perfectly.
The problem is that, when selecting more than one radio button they all stay selected.
It shouldn't be like this. It should deselect the previous choice when selecting another one.
I'm one week stuck with this trick and I don't know how to solve.
Any help I'll be appreciated.
This is a part of my View:
<table>
<tr>
<td>
#Html.TextAreaFor(c => c.AnsLst[0].AnswerBody)
</td>
<td>
#Html.RadioButtonFor(c => c.AnsLst[0].Correct, true)
</td>
</tr>
<tr>
<td>
#Html.TextAreaFor(c => c.AnsLst[1].AnswerBody)
</td>
<td>
#Html.RadioButtonFor(c => c.AnsLst[1].Correct, true)
</td>
</tr>
<tr>
<td>
#Html.TextAreaFor(c => c.AnsLst[2].AnswerBody)
</td>
<td>
#Html.RadioButtonFor(c => c.AnsLst[2].Correct, true)
</td>
</tr>
</table>

Answer 1

If you are using a radio button group in which only one value can be selected at a time you should bind them to a single property on your view model which will hold the selected value and not to a collection:
<table>
<tr>
<td>
#Html.TextAreaFor(c => c.AnsLst[0].AnswerBody)
</td>
<td>
#Html.RadioButtonFor(c => c.Answer, "value 1")
</td>
</tr>
<tr>
<td>
#Html.TextAreaFor(c => c.AnsLst[1].AnswerBody)
</td>
<td>
#Html.RadioButtonFor(c => c.Answer, "value 2")
</td>
</tr>
<tr>
<td>
#Html.TextAreaFor(c => c.AnsLst[2].AnswerBody)
</td>
<td>
#Html.RadioButtonFor(c => c.Answer, "value 3")
</td>
</tr>
</table>
Now since the 3 radio buttons are bound to the same property on your view model (Answer) when the form is submitted this property will get the value of the selected answer. The value that will be sent is the one passed as second argument to the RadioButton helper.
So basically you will have the following property on your view model to store the answer:
public string Answer { get; set; }
In y example I have set some arbitrary values for the answers but you could use for example the id of the answer so that you could identify it:
#Html.RadioButtonFor(c => c.Answer, c.AnsLst[0].AnswerId)
#Html.RadioButtonFor(c => c.Answer, c.AnsLst[1].AnswerId)
#Html.RadioButtonFor(c => c.Answer, c.AnsLst[2].AnswerId)