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From "" <>
Subject RE: Radio button grouping in Struts 2
Date Mon, 11 May 2009 18:39:01 GMT

Hi Radu. Many thanks for your reply, and sorry for not responding sooner as
I've only just got around to looking at your link.

It definitely helped and I've got it working now. It's slightly different
and doesn't rely on Preparable:

class Question
    long id;
    String name;

public class ViewQuestionsAction
    // NOTE - getters required for all these properties
    List<Question> questions;
    List<String> answersList;  
    Map<Long, String> answersMap;

<s:set name="answersList" value="%{answersList}"/>
<s:set name="answersMap" value="%{answersMap}"/>
<s:iterator value="questions" status="question_stat">  
    <s:property value="name"/><br/>
    <s:radio name="answers[%{id}]" value="%{#answersMap[id]}"
list="#answersList" />

public class SaveAnswersAction
    // NOTE - getter AND setter required for this map
    private Map<Long, String> answersMap;

In the ViewQuestionsAction (which sources the JSP):
1) loads the questions from the DB;
2) populates all the possible answers into the answersList
3) populates the map with the current answers, keyed by question id

When the page loads, the current answer is selected in the radio (due to
value selecting the answer from the answersMap), and the radios are unique
by question because the name is unique by question (due to the map keyed by

When you click save, the SaveAnswersAction.answersMap map is populated with
the selected answers, keyed by the question's id (no prepareable method
needed). You can then do all the validation you need and update the DB as

I believe this is a really nice solution as loading entities from the DB in
a prepare() method seems wrong to me. I'd be interested to hear what other
people think. 

Many thanks

Rubbinio wrote:
> You need to use Map backed properties if you want to get this to work.
> Take a look at this example and you should be able to adapt it.
> Basically your properties are a map with id and Question objects and then
> struts can repopulate your answers in the correct question object in the
> map. It works very nice. I used it for a page that had a random number of
> file uploads.
> Radu
> -----Original Message-----
> From: Jon Pearson []
> Sent: May 4, 2009 8:18 AM
> To: Struts Users Mailing List
> Subject: RE: Radio button grouping in Struts 2
>> Hi all,
>> I have a page which iterates over a collection of questions,
>> with each question having a number of radio buttons which can
>> be used to select the answer to that question. For example:
>> Question 1:   Unanswered O  Yes O  No O
>> Question 2:   Unanswered O  Yes O  No O
>> etc..
>> If the question has already been answered previously when the
>> pages loads then the appropriate Yes/No is selected;
>> otherwise Unanswered is selected.
>> I've got this working fine using the following:
>> class Question {
>>   long id;
>>   String name;
>>   String answer;
>> }
>> class ViewQuestionsAction {
>>   List<Question> questions;
>>   Map<String,String> answersMap; // key == value at the
>> moment because didn't seem to work with int keys
>> <s:set name="answersMap" value="%{answersMap}"/> <s:iterator
>> value="questions">
>>   <s:property value="name"/>
>>   <s:radio name="%{id}" value="%{answer}"
>> list="#answersMap"/> </s:iterator>
>> I need the name=%{id} bit so that I can group the radio
>> buttons per question. And this is the problem, because then I
>> can't find a way for when you submit the form to receive an
>> array of the selected buttons into the target action. The
>> above works on page load (grouped nicely), but on submit I
>> get all kinds of OGNL errors complaining about long id
>> invalid expressions (understandable I guess). But when I
>> choose a sensible name, for example:
>>   <s:radio name="responses" value="%{answer}" list="#answersMap"/>
>> I get an array of selected buttons in the target action's
>> responses property on submit but the radio grouping isn't
>> working - you can only select on radio button from the whole
>> page because they all share the same name element in the
>> HTML. I then tried:
>>   <s:radio id="ViewQuestions_responses" name="%{id}" value="%{answer}"
>> list="#answersMap"/>
>> To try and force struts to set the responses property, but it
>> still tries to set the property from the name. Which makes me
>> think: if struts always uses the name to set the property,
>> and the browser always groups the radio buttons based on the
>> same name, is what I'm trying to do even possible?!?!
>> Any help gratefully received :)
>> Many thanks
>> James
>> --
>> View this message in context:
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> You could, instead of relying on Struts2 to automatically call the
> proper set* routines on submit, implement Preparable and manually parse
> the results in the prepare() function, which is called BEFORE any set*
> functions.
> ~Jonathan
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