I am creating a web application, where you have to read a list of objects / entities from a DB and populate it in a JSF <h:selectOneMenu>. I am unable to code this. Can someone show me how to do it?
I know how to get a List<User> from the DB. What I need to know is, how to populate this list in a <h:selectOneMenu>.
<h:selectOneMenu value="#{bean.name}">
...?
</h:selectOneMenu>
Based on your question history, you're using JSF 2.x. So, here's a JSF 2.x targeted answer. In JSF 1.x you would be forced to wrap item values/labels in ugly SelectItem instances. This is fortunately not needed anymore in JSF 2.x.
Basic example
To answer your question directly, just use <f:selectItems> whose value points to a List<T> property which you preserve from the DB during bean's (post)construction. Here's a basic kickoff example assuming that T actually represents a String.
<h:selectOneMenu value="#{bean.name}">
<f:selectItems value="#{bean.names}" />
</h:selectOneMenu>
with
#ManagedBean
#RequestScoped
public class Bean {
private String name;
private List<String> names;
#EJB
private NameService nameService;
#PostConstruct
public void init() {
names = nameService.list();
}
// ... (getters, setters, etc)
}
Simple as that. Actually, the T's toString() will be used to represent both the dropdown item label and value. So, when you're instead of List<String> using a list of complex objects like List<SomeEntity> and you haven't overridden the class' toString() method, then you would see com.example.SomeEntity#hashcode as item values. See next section how to solve it properly.
Also note that the bean for <f:selectItems> value does not necessarily need to be the same bean as the bean for <h:selectOneMenu> value. This is useful whenever the values are actually applicationwide constants which you just have to load only once during application's startup. You could then just make it a property of an application scoped bean.
<h:selectOneMenu value="#{bean.name}">
<f:selectItems value="#{data.names}" />
</h:selectOneMenu>
Complex objects as available items
Whenever T concerns a complex object (a javabean), such as User which has a String property of name, then you could use the var attribute to get hold of the iteration variable which you in turn can use in itemValue and/or itemLabel attribtues (if you omit the itemLabel, then the label becomes the same as the value).
Example #1:
<h:selectOneMenu value="#{bean.userName}">
<f:selectItems value="#{bean.users}" var="user" itemValue="#{user.name}" />
</h:selectOneMenu>
with
private String userName;
private List<User> users;
#EJB
private UserService userService;
#PostConstruct
public void init() {
users = userService.list();
}
// ... (getters, setters, etc)
Or when it has a Long property id which you would rather like to set as item value:
Example #2:
<h:selectOneMenu value="#{bean.userId}">
<f:selectItems value="#{bean.users}" var="user" itemValue="#{user.id}" itemLabel="#{user.name}" />
</h:selectOneMenu>
with
private Long userId;
private List<User> users;
// ... (the same as in previous bean example)
Complex object as selected item
Whenever you would like to set it to a T property in the bean as well and T represents an User, then you would need to bake a custom Converter which converts between User and an unique string representation (which can be the id property). Do note that the itemValue must represent the complex object itself, exactly the type which needs to be set as selection component's value.
<h:selectOneMenu value="#{bean.user}" converter="#{userConverter}">
<f:selectItems value="#{bean.users}" var="user" itemValue="#{user}" itemLabel="#{user.name}" />
</h:selectOneMenu>
with
private User user;
private List<User> users;
// ... (the same as in previous bean example)
and
#ManagedBean
#RequestScoped
public class UserConverter implements Converter {
#EJB
private UserService userService;
#Override
public Object getAsObject(FacesContext context, UIComponent component, String submittedValue) {
if (submittedValue == null || submittedValue.isEmpty()) {
return null;
}
try {
return userService.find(Long.valueOf(submittedValue));
} catch (NumberFormatException e) {
throw new ConverterException(new FacesMessage(String.format("%s is not a valid User ID", submittedValue)), e);
}
}
#Override
public String getAsString(FacesContext context, UIComponent component, Object modelValue) {
if (modelValue == null) {
return "";
}
if (modelValue instanceof User) {
return String.valueOf(((User) modelValue).getId());
} else {
throw new ConverterException(new FacesMessage(String.format("%s is not a valid User", modelValue)), e);
}
}
}
(please note that the Converter is a bit hacky in order to be able to inject an #EJB in a JSF converter; normally one would have annotated it as #FacesConverter(forClass=User.class), but that unfortunately doesn't allow #EJB injections)
Don't forget to make sure that the complex object class has equals() and hashCode() properly implemented, otherwise JSF will during render fail to show preselected item(s), and you'll on submit face Validation Error: Value is not valid.
public class User {
private Long id;
#Override
public boolean equals(Object other) {
return (other != null && getClass() == other.getClass() && id != null)
? id.equals(((User) other).id)
: (other == this);
}
#Override
public int hashCode() {
return (id != null)
? (getClass().hashCode() + id.hashCode())
: super.hashCode();
}
}
Complex objects with a generic converter
Head to this answer: Implement converters for entities with Java Generics.
Complex objects without a custom converter
The JSF utility library OmniFaces offers a special converter out the box which allows you to use complex objects in <h:selectOneMenu> without the need to create a custom converter. The SelectItemsConverter will simply do the conversion based on readily available items in <f:selectItem(s)>.
<h:selectOneMenu value="#{bean.user}" converter="omnifaces.SelectItemsConverter">
<f:selectItems value="#{bean.users}" var="user" itemValue="#{user}" itemLabel="#{user.name}" />
</h:selectOneMenu>
See also:
Our <h:selectOneMenu> wiki page
View-Page
<h:selectOneMenu id="selectOneCB" value="#{page.selectedName}">
<f:selectItems value="#{page.names}"/>
</h:selectOneMenu>
Backing-Bean
List<SelectItem> names = new ArrayList<SelectItem>();
//-- Populate list from database
names.add(new SelectItem(valueObject,"label"));
//-- setter/getter accessor methods for list
To display particular selected record, it must be one of the values in the list.
Roll-your-own generic converter for complex objects as selected item
The Balusc gives a very useful overview answer on this subject. But there is one alternative he does not present: The Roll-your-own generic converter that handles complex objects as the selected item. This is very complex to do if you want to handle all cases, but pretty simple for simple cases.
The code below contains an example of such a converter. It works in the same spirit as the OmniFaces SelectItemsConverter as it looks through the children of a component for UISelectItem(s) containing objects. The difference is that it only handles bindings to either simple collections of entity objects, or to strings. It does not handle item groups, collections of SelectItems, arrays and probably a lot of other things.
The entities that the component binds to must implement the IdObject interface. (This could be solved in other way, such as using toString.)
Note that the entities must implement equals in such a way that two entities with the same ID compares equal.
The only thing that you need to do to use it is to specify it as converter on the select component, bind to an entity property and a list of possible entities:
<h:selectOneMenu value="#{bean.user}" converter="selectListConverter">
<f:selectItem itemValue="unselected" itemLabel="Select user..."/>
<f:selectItem itemValue="empty" itemLabel="No user"/>
<f:selectItems value="#{bean.users}" var="user" itemValue="#{user}" itemLabel="#{user.name}" />
</h:selectOneMenu>
Converter:
/**
* A converter for select components (those that have select items as children).
*
* It convertes the selected value string into one of its element entities, thus allowing
* binding to complex objects.
*
* It only handles simple uses of select components, in which the value is a simple list of
* entities. No ItemGroups, arrays or other kinds of values.
*
* Items it binds to can be strings or implementations of the {#link IdObject} interface.
*/
#FacesConverter("selectListConverter")
public class SelectListConverter implements Converter {
public static interface IdObject {
public String getDisplayId();
}
#Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
if (value == null || value.isEmpty()) {
return null;
}
return component.getChildren().stream()
.flatMap(child -> getEntriesOfItem(child))
.filter(o -> value.equals(o instanceof IdObject ? ((IdObject) o).getDisplayId() : o))
.findAny().orElse(null);
}
/**
* Gets the values stored in a {#link UISelectItem} or a {#link UISelectItems}.
* For other components returns an empty stream.
*/
private Stream<?> getEntriesOfItem(UIComponent child) {
if (child instanceof UISelectItem) {
UISelectItem item = (UISelectItem) child;
if (!item.isNoSelectionOption()) {
return Stream.of(item.getValue());
}
} else if (child instanceof UISelectItems) {
Object value = ((UISelectItems) child).getValue();
if (value instanceof Collection) {
return ((Collection<?>) value).stream();
} else {
throw new IllegalStateException("Unsupported value of UISelectItems: " + value);
}
}
return Stream.empty();
}
#Override
public String getAsString(FacesContext context, UIComponent component, Object value) {
if (value == null) return null;
if (value instanceof String) return (String) value;
if (value instanceof IdObject) return ((IdObject) value).getDisplayId();
throw new IllegalArgumentException("Unexpected value type");
}
}
I'm doing it like this:
Models are ViewScoped
converter:
#Named
#ViewScoped
public class ViewScopedFacesConverter implements Converter, Serializable
{
private static final long serialVersionUID = 1L;
private Map<String, Object> converterMap;
#PostConstruct
void postConstruct(){
converterMap = new HashMap<>();
}
#Override
public String getAsString(FacesContext context, UIComponent component, Object object) {
String selectItemValue = String.valueOf( object.hashCode() );
converterMap.put( selectItemValue, object );
return selectItemValue;
}
#Override
public Object getAsObject(FacesContext context, UIComponent component, String selectItemValue){
return converterMap.get(selectItemValue);
}
}
and bind to component with:
<f:converter binding="#{viewScopedFacesConverter}" />
If you will use entity id rather than hashCode you can hit a collision- if you have few lists on one page for different entities (classes) with the same id
Call me lazy but coding a Converter seems like a lot of unnecessary work. I'm using Primefaces and, not having used a plain vanilla JSF2 listbox or dropdown menu before, I just assumed (being lazy) that the widget could handle complex objects, i.e. pass the selected object as is to its corresponding getter/setter like so many other widgets do. I was disappointed to find (after hours of head scratching) that this capability does not exist for this widget type without a Converter. In fact if you supply a setter for the complex object rather than for a String, it fails silently (simply doesn't call the setter, no Exception, no JS error), and I spent a ton of time going through BalusC's excellent troubleshooting tool to find the cause, to no avail since none of those suggestions applied. My conclusion: listbox/menu widget needs adapting that other JSF2 widgets do not. This seems misleading and prone to leading the uninformed developer like myself down a rabbit hole.
In the end I resisted coding a Converter and found through trial and error that if you set the widget value to a complex object, e.g.:
<p:selectOneListbox id="adminEvents" value="#{testBean.selectedEvent}">
... when the user selects an item, the widget can call a String setter for that object, e.g. setSelectedThing(String thingString) {...}, and the String passed is a JSON String representing the Thing object. I can parse it to determine which object was selected. This feels a little like a hack, but less of a hack than a Converter.
I have a form where I create a user. In my form, I have multiple properties for that user (I actually use a User object for the retainment of data on submit to the backing bean)
create.xhtml
<h:form>
<h:outputLabel for="user_name" value="Name:" />
<h:inputText id="user_name" value="#{createUserView.newUser.username}" />
<br/><br/>
<h:outputLabel for="user_password" value="Default Password*:" />
<h:inputSecret id="user_password" value="#{createUserView.newUser.password}"></h:inputSecret><br/><br/>
<h:outputLabel for="user_organization" value="Organization:" />
<h:selectOneMenu id="user_organization" disabled="true" value="#{createUserView.newUser.organizationId}">
<f:selectItems
value="#{organizationBean.allOrganizations}"
var="org"
itemLabel="#{org.organizationName}"
itemValue="#{org.id}" />
</h:selectOneMenu><br/><br/>
<h:commandButton value="Create" action="#{createUserView.createNewUser}" />
</h:form>
CreateUserView
#ManagedBean(name = "createUserView")
#RequestScoped
public class CreateUserView {
private UserServices userSerivces;
private User newUser;
#ManagedProperty(value="#{organizationBean}")
private OrganizationBean organizationBean;
public CreateUserView() {
newUser = new User();
userSerivces = new UserServices();
}
public void createNewUser() {
userSerivces.createNewUser(newUser);
}
// Getters and Setters
}
OrganizationBean
#ManagedBean(name = "organizationBean")
#RequestScoped
public class OrganizationBean {
private List<Organization> allOrganizations;
private OrganizationServices orgServices;
public OrganizationBean() {
orgServices = new OrganizationServices();
allOrganizations = orgServices.retrieveAllOrganizations();
}
// Getters and Setters
}
The issue here is that when I reference the newUser object in the backing bean, the organizationId value is null.
I assume this is because OrganizationBean (excuse the confusing in naming, refactoring) is either not rendered for my current view or I need to somehow inject.
I've tried a managed property in the CreateUserView backing bean that references the OrganizationBean, but no luck. The organizationID value in the newUser object is null.
Do I need to populate a list in the CreateUserView bean using the OrganizationBean injection, so that it has it's own list it can render?
What am I missing? Feeling foolish.
JSF 2.0
The problem, as stated in the comments is that you don't have a Converter for your Organization class.
You must have it in order to know what Organization matches every SelectItem. The converter must be something like:
#FacesConverter(forClass = Organization.class, value = "organizationConverter")
public class OrganizationConverter implements Converter
{
#Override
public Object getAsObject(FacesContext fc, UIComponent uic, String id)
{
if (StringUtils.isEmpty(id))
{
return null;
}
// Convert id to an Organizacion
return organization;
}
#Override
public String getAsString(FacesContext fc, UIComponent uic, Object o)
{
if (o instanceof Organization)
{
return ...;//Convert organization to id
}
return null;
}
}
And then in your selectonemenu:
<h:selectOneMenu id="user_organization" disabled="true" value="#{createUserView.newUser.organizationId}"
converter="organizationConverter">
I already tried to search through this site, but maybe I'm not getting understand well.
Please kindly advice for my cases..
I'm using Netbeans 7.3 + Primefaces + Hibernate.
I want to show a list from my query.
My query already in.. and there's no error showup, but the display is not what I want (I think it returning an object or something, not sure).
Please kindly correct me if I'm missed something.
Here's my PtlLovBean
#ManagedBean(name = "ptlLovBean")
#SessionScoped
public class PtlLovBean implements Serializable {
private static final String FLIGHT = "LOV_FLIGHT";
private List lovFlight;
public List getLovFlight() {
PtlLovDao ptlLovDao = new PtlLovDaoImpl();
return ptlLovDao.getByKey(FLIGHT);
}
}
Here's ptlLovDao
public interface PtlLovDao {
public List getByKey(String key);
}
Here's PtlLovDaoImpl
public class PtlLovDaoImpl implements PtlLovDao {
#Override
public List getByKey(String key) {
Session session = HibernateUtil.getSessionFactory().openSession();
Query query = session.createQuery("from PtlLov where LOV_KEY = :param");
query.setParameter("param", key);
return query.list();
}
}
Here's my JSF :
<p:selectOneMenu id="flightName" value="#{wizard.user.selectedFlightName}">
<f:selectItem itemLabel="Select Flight" itemValue="" />
<f:selectItems value="#{ptlLovBean.lovFlight}" />
</p:selectOneMenu>
Display after Code:
Sorry I'm not capable to insert picture, so here's the image link :
http://i117.photobucket.com/albums/o56/po_se_for/PIC_zps88ec4983.png
You can either override the toString method in your PtlLov class or define itemValue and itemLabel properties in your f:selectItems tag.
Something like this:
<f:selectItems value="#{ptlLovBean.lovFlight}" var="flight"
itemValue="#{flight}" itemLabel="#{flight.description}" />
In my code, I have a PrimeFaces' wizard component with several tabs as following:
<h:form id="myForm">
<p:wizard flowListener="#{mrBean.flowControl}" widgetVar="wiz">
<p:tab id="tab1"></p:tab>
<p:tab id="tab2"></p:tab>
<p:tab id="tab3">
<h:selectOneMenu id="couponList" value="#{mrBean.coupon}"
converter="#{codeToCouponConverter}" >
<f:ajax listener="#{mrBean.doSomething}" execute="#this"/>
<f:selectItem noSelectionOption="true" itemLabel="Choose one..." />
<f:selectItems value="#{mrBean.coupons}" var="c"
itemValue="#{c}" itemLabel="#{c.name} - $ #{c.discount}" />
</h:selectOneMenu>
</p:tab>
</p:wizard>
</h:form>
This is the code for the managed bean:
#ManagedBean(name = "mrBean")
#ViewScoped
public class MrBean {
private List<Coupon> coupons;
private Coupon coupon;
public void doSomething() {
System.out.println("DONE");
}
public String flowControl(FlowEvent event) {
...
}
// Getters and Setters
}
In 1 of the tab, I have a <h:selectOneMenu> component which contains a <f:ajax> tag. I have no idea why the listener is only triggered when I choose the Choose one... option. When I choose any other options from the mrBean.coupons list, the listener is never triggered. In other words, I never saw any DONE printed on the console.
*UPDATE***: The problem turns out to be coming from the following Converter:
#RequestScoped
#ManagedBean
public class CodeToCouponConverter implements Converter {
#EJB
private MrsBeanInterface mrsBean;
#Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
String couponCode = value;
if (value != null) return mrsBean.getCoupon(couponCode);
else return null;
}
#Override
public String getAsString(FacesContext context, UIComponent component, Object value) {
if (value != null) {
Coupon c = (Coupon) value;
return c.getId();
} else return null;
}
// Getters and Setters
public MrsBeanInterface getMrsBean() {
return mrsBean;
}
public void setMrsBean(MrsBeanInterface mrsBean) {
this.mrsBean = mrsBean;
}
}
If I change the <h:selectOneMenu> as following:
<h:selectOneMenu id="couponList" value="#{mrBean.couponCode}" >
<f:ajax listener="#{mrBean.doSomething}" execute="#this"/>
<f:selectItem noSelectionOption="true" itemLabel="Choose one..." />
<f:selectItems value="#{mrBean.coupons}" var="c"
itemValue="#{c.id}" itemLabel="#{c.name} - $ #{c.discount}" />
</h:selectOneMenu>
and update the mrBean.doSomething function as following:
#EJB
private MrsBeanInterface mrsBean;
private String couponCode;
private Coupon coupon;
public void doSomething() {
this.coupon = mrsBean.getCoupon(couponCode);
System.out.println("DONE");
}
everything works perfectly.
I would be very grateful if you could give me an explanation of what I have done wrong with the Converter.
Best regards,
James Tran
Use #{mrBean.doSomething()} with the braces or add the event parameter to the method.
I use this class for doing validation from input fields:
#ManagedBean
#RequestScoped
public class UserInputValidation {
public void validateCity(FacesContext context, UIComponent validate,
Object value) {
String inputFromField = (String) value;
if (inputFromField.equals("") || inputFromField.equals(" ")) {
FacesMessage msg = new FacesMessage("Odaberite grad");
throw new ValidatorException(msg);
}
}
//...
}
And this is the managed bean that holds the inputed values:
#ManagedBean
#RequestScoped
public class InputController {
//Attributes
private String city;
//Get set methods
Why when i create a selectOneComponent and i select the first component(blank input), the validation message is not shown?
<h:selectOneMenu id="city" value="#{inputController .city}">
<f:selectItems value="#{searchController.formatedCities()}" validator="#{userInputValidation.validateCity}"/>
</h:selectOneMenu>
<span style="color: red;"><b><h:message for="city"
showDetail="true" /></b></span>
The first of the fields in the selectOneMenu is a blank(The formatedCitiesMethod() returns a "" as first element), so why the validation message is not being shown if the form is submit button is clicked with the blank selected?
The validator attribute has to go in the <h:selectOneMenu>, not in the <f:selectItems>
Said that, why don't you just use required="true"? Why is the validator a #ManagedBean instead of a #FacesValidator?