Wicket : Submitting data with a listview inside a form - forms

Question

I have the following issues:
Imagine a wicket list view that looks something like this:
ListView<Question> lvQuestion = new ListView<Question>("lvQuestion",
questions) {
private static final long serialVersionUID = 1L;
#Override
protected void populateItem(ListItem<Question> item) {
Question q = item.getModelObject();
item.add(new Label("question", q.getQuestion()));
List<String> possibleAnswers = getFromDb();
q.setPossibleAnswers(possibleAnswers);
if(q.getComponent().equals("dropDown")){
item.add(new DropDownPanel("questionComponent", q));
}
}
};
This listview is created within a form component; what i need to do is take every question answered using this listview and record them in the database.
Problem being though is that I don't know how many drop down panels there will be so there is always going to be a dynamic set of questions returned.
Is there a way of ensuring that when the parent form is submitted every model in the listview is submitted to the database.

Answer 1

What I do for these situations is maintain a hashmap with the selected option for each question. I update it with AjaxFormComponentUpdatingBehavior such as the following:
First, declare & initialize the map (There may be a more efficient way of doing this)
Map<Question, String> qMap = new HashMap<>();
for(Question q : questions) {
qMap.put(q, "");
}
Then, update the map within your ListView (you probably want to set q as final when you initialize it)
if(q.getComponent().equals("dropDown")) {
DropDownPanel ddp = new DropDownPanel("questionComponent", q);
ddp.add(new AjaxFormComponentUpdatingBehavior("onchange") {
#Override
protected void onUpdate(AjaxRequestTarget art) {
String answer = (String) getFormComponent().getConvertedInput();
qMap.put(q, answer);
}
}
item.add(ddp);
}
This allows you to keep the qMap up to date and process it when the form is submitted.
Alternatively, if you have a String attribute to hold the answer on the Question object and you make sure your ListView.list and your List questions stay consistent, you can do the following in the onUpdate() without needing the map:
q.setAnswer(answer);
questions.set(item.getIndex(), q);
In this case you would just process the questions list in the form's onSubmit().