JSF - Loading UISelectItem list in constructor

Question

I am running an application using JSF2.0 and Primefaces 2.2RC2

I have run the profiler on my project and determined there was a bottleneck coming from a UISelectItems list. The list was being populated like 6 times on each action in my application.

The UISelectItem list was being populated in a getter method called getCountryList() and it looked like this

public UISelectItems getCountryList() throws Exception {
    Collection List = new ArrayList();
    List<Countries> c_list = myDao.getCountryList();

    for( QcardCountries c : c_list ) {
       list.add(new SelectItem(c.getCountryId().toString(), c.getCountryName());
    }

    UISelectItems countries = new UISelectItems();
    countries.setValue(list);
    return countries;
}

This works when I call in the views like so

<f:selectItems binding="#{myBean.countryList}" />

but again it is called like 6 times for each button or action I make in the application.

I then attempted to move the creation of the List into a method that was called on @PostContruct but when I do that the list does not show up when I use

 <f:selectItems binding="#{myBean.countryList}" />

It just shows up as empty. Does anyone know how to properly create a list so it is only created one time and can be called throughout an entire users session to populate a dropdown list?

score 2 · Answer 1 · answered Jan 12 '11 at 18:45

2

take list out at class's field , initialize it in @postconstruct , in get method check if its null create it and return it or else return it,

answered Jan 12 '11 at 18:45

jmj

237,923
42
401
438

Correct, but nullcheck in getter is unnecessary. – BalusC Jan 12 '11 at 18:50
So I put List c_list = myDao.getCountryList(); in my @PostConstruct? I am confused as to what I should load in there – newtoJSF Jan 12 '11 at 18:55
yes you are correct, just take list at class field, as shown by @BalusC – jmj Jan 12 '11 at 19:05

score 2 · Accepted Answer · edited Jun 20 '20 at 09:12

org.life.java already gave a hint about loading, but since you're unnecessarily using binding and JSF 2.0 provides a way to just take List<SomeBean> instead of List<SelectItem> as value, here's a complete example how to do it the right way:

private List<Country> countries;

@PostConstruct
public void init() {
    countries = myDao.getCountryList();
}

public List<Country> getCountries() {
    return countries;
}

with

<f:selectItems value="#{bean.countries}" var="country" itemValue="#{country.id}" itemLabel="#{country.name}" />

(note that I renamed Countries model to Country and getCountryId() to getId() and getCountryName() to getName() since that makes more sense)

JSF - Loading UISelectItem list in constructor

2 Answers2

See also: