Problems with ajax in jsf updating an output text field - ajax

Question

I'm new to JSF and in class we should just set up a little "Pizza-Service" with logins etc. On the Page where i want to prepare my Order as a user I've a data table (primeface data table) with 4 columns. The last one is for the number of pizza of the type in the current cell.
What I want: If I am typing in a Number i want to set up a current Order (works fine so far with ajax) in the same moment i just want to show the user the current price. This is the little thing that is not working.
When I am using the tag there is just nothing happening and if I am taking the tag I'm getting this mistake:
<f:ajax> contains an unknown id 'ausgabe' - cannot locate it in the context of the component menge
What I thought was take the ajax tag set up a function (take the current order) and render an output text where the calculated price is shown directly. I called those function in german so bestellungAufnehmen = takeOrder and preisBerechnen = calculatePrice.
Thanks if someone could help me!
Here is the xhtml:
<h:head>
<title>Facelet Title</title>
</h:head>
<h:body>
<h:form>
<p:dataTable id="table" var="pizza" value="#{model.getPizzen()}">
<p:column headerText="Nr">
<h:outputText value="#{pizza.nr}"/>
</p:column>
<p:column headerText="Artikel">
<h:outputText value="#{pizza.name}"/>
</p:column>
<p:column headerText="Preis">
<h:outputText value="#{pizza.preis}"/>
</p:column>
<p:column headerText ="Menge">
<h:inputText id="menge" value="#{bestellung.anzahl}">
<f:ajax event="keyup" render="ausgabe" listener="#{bestellung.bestellungAufnehmen(pizza)}"/>
</h:inputText>
</p:column>
</p:dataTable>
<h:outputLabel value="Zu Zahlen: "/>
<h:outputText id="ausgabe" value="#{bestellung.preisBerechnen()} €"/>
</h:form>
</h:body>
and here is the the Bean with those functions.
#Named
#SessionScoped
public class Bestellung implements Serializable {
private static int bstzaehler=0;
private int bstnr;
private Map<String,Bestellposten> posten;
private int anzahl;
public Bestellung(){
this.bstnr=++bstzaehler;
this.posten = new HashMap<>();
}
/**
* #return the bstnr
*/
public int getBstnr() {
return bstnr;
}
/**
* #param bstnr the bstnr to set
*/
public void setBstnr(int bstnr) {
this.bstnr = bstnr;
}
public void bestellungAufnehmen(Pizza pizza){
if(this.posten.containsKey(pizza.getName()) == false){
Bestellposten b = new Bestellposten(this.getAnzahl(), pizza);
this.posten.put(pizza.getName(),b);
} else {
if(this.getAnzahl() > 0 ){
Bestellposten tmp = this.posten.get(pizza.getName());
tmp.setMenge(this.getAnzahl());
} else {
this.posten.remove(pizza.getName());
}
}
System.out.println("groesse: "+posten.size());
System.out.println("akt preis: "+this.preisBerechnen());
}
/**
* #return the anzahl
*/
public int getAnzahl() {
return anzahl;
}
/**
* #param anzahl the anzahl to set
*/
public void setAnzahl(int anzahl) {
this.anzahl = anzahl;
}
public double preisBerechnen(){
double sum = 0.0;
for(String key : this.posten.keySet()){
Pizza tmp = this.posten.get(key).getPizza();
sum += tmp.getPreis() * this.posten.get(key).getMenge();
}
return sum;
}
}

Answer 1

Try giving the full qualified id for the component:
<h:form id="frmPizza">
<p:dataTable id="table" var="pizza" value="#{model.getPizzen()}">
<p:column headerText="Nr">
<h:outputText value="#{pizza.nr}"/>
</p:column>
<p:column headerText="Artikel">
<h:outputText value="#{pizza.name}"/>
</p:column>
<p:column headerText="Preis">
<h:outputText value="#{pizza.preis}"/>
</p:column>
<p:column headerText ="Menge">
<h:inputText id="menge" value="#{bestellung.anzahl}">
<f:ajax event="keyup" render=":frmPizza:ausgabe" listener="#{bestellung.bestellungAufnehmen(pizza)}"/>
</h:inputText>
</p:column>
</p:dataTable>
<h:outputLabel value="Zu Zahlen: "/>
<h:outputText id="ausgabe" value="#{bestellung.preisBerechnen()} €"/>
</h:form>

Answer 2

I think, you should use update attribute to update that outputText, like update=":FormId:ausgabe"
<f:ajax event="keyup"
render=":frmPizza:ausgabe"
listener="#{bestellung.bestellungAufnehmen(pizza)}"
update=":frmPizza:ausgabe" />

Answer 3

The solution of luiggi worked but i couldnt answer directly because of my "low-level" here.
Iam not on my computer right now but isnt "update" an attribute of p:ajax and not of f:ajax and is the same as render? but i will try it aswell later on.
thx!