selecting correct item of List<bean> in selectOneMenu

Question

I can't get the bean to update when I choose another name from the list

<h:selectOneMenu id="playerMenu" value="#{player.combinedName}">
<f:selectItems value="#{serviceHCP.allPlayers}" />                  
<f:ajax execute="playerMenu" render="playerMenu" />

If I use above method I will always end upp with player == null

If I use it without the f:ajax I will always end up with the same "player". But of course I want to have the one selected in the menu item.

I will then pass it to a bean

<h:commandButton value="Visa lista" action="#{serviceSeries.getSeriesForPlayerInfo(club.name, player, serieType.serie_type, calendarBean) }">
                </h:commandButton>
public List<Player> getAllPlayers() {

if (factory == null) {
    factory = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
}

EntityManager em = factory.createEntityManager();
//Order by the matchdate.
//Query q = em.createQuery("select t from DBTest t");
Query q = em.createQuery("select t from Player t");

List<Player> players = q.getResultList();
for (Player aPlayer : players) {
  System.out.println(aPlayer);
}
System.out.println("Size: " + players.size());

em.close();

return players;

}

Answer 1

You have to write a custom jsf converter to convert your Player object. Your converter will most likely be..

@FacesConverter("playerConverter")
public class PlayerConverter implements Converter {
    @Override
    public String getAsString(FacesContext context, UIComponent component, Object value) throws ConverterException {
        // Convert Object to unique String representation for display.
        return String.valueOf(((Player) value).getId());
    }
    @Override
    public Object getAsObject(FacesContext context, UIComponent component, String value) throws ConverterException {
        // Convert submitted unique String representation back to Object.
        return new Player(Long.valueOf(value));
    }
}

And your select one should look like,

<h:selectOneMenu id="playerMenu" value="#{XXXXXX.player}">
    <f:selectItems value="#{serviceHCP.allPlayers}" var="player" itemLabel="#{player.name}" itemValue="#{player.id}"/>
    <f:converter converterId="playerConverter" />
</h:selectOneMenu>

Answer 2

If you have a problem using the Converter, the why don't you use java.util.Map to hold the Player data.
Using map may also be helpful in other operations.
JSF h:selectOneMenu supports java.util.Map too.

If you have Map then K will become the itemLabel and V will become the itemValue.
You can load the Player Objects to as Values to Map.

Map<String,Player> playerMap = new LinkedHashMap<>();
Player selectedPlayer;

then..,

<h:selectOneMenu value="#{bean.selectedPlayer}">
   <f:selectItems values="#{bean.playerMap}"/>
</h:selectOneMenu>

If you want Orders Map collection to preserve Insertion order use LinkeHashMap

See Wiki page for h:selectOneMenu