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 am using JSF 2.x in my project.
I have two pages and two managed beans (request scoped) for these two pages.
Page 1 is loaded after user clicks on a link on Home page. This link calls view() method of Bean1 (with request parameter ID=some value) in which we load some data from DB (based on ID) and then redirects to page 1 where this data is displayed.
Later, user navigates from page 1 to page 2 and here we pass the same ID to the page 2.
On page 2, user enters data and clicks on Save button. This will call saveDetails() method of Bean 2.
After the saveDetails() method I want to redirect to page 1 by calling Bean1's view() method and passing the ID as request parameter. I cannot redirect directly to page1 because then there will be no data to display as the bean1 is request scoped.
Hence, I want to call bean1.view() with request parameter ID. I.e. I want to achieve the same behavior as if user has clicked on the link on Home page.
How to achieve this?
Here is the code so far:
#ManagedBean
#Component
#RequestScoped
#Scope("request")
// bean for page1
public class ModifyCDSPageBean extends BasePageBean {
private DisplayTicket ticket;
private String selectedCDS;
...
...
// CDS List
private static Map<String, String> cdsList = new LinkedHashMap<String, String>();
#Autowired
TicketConsoleGTRDao ticketConsoleGTRDao;
private static final Logger LOGGER = Logger.getLogger(ModifyCDSPageBean.class);
public String viewTicketDetails() {
populateCDSList();
....
// Method updated to set DisplayInfoTravail
String id_incident = getRequestParameterValue(TicketConstants.ID_INCIDENT);
List<InfoTravail> travailsList =
ticketConsoleGTRDao.findMatchingTrvailInformation(id_incident);
....
return NavigationConstants.PAGE_MODIFY_CDS;
}
...
...
}
#ManagedBean
#Component
#RequestScoped
#Scope("request")
//Bean for page 2
public class CreateInfoTravailPageBean extends BasePageBean {
private String selectedTypeInfoTravail;
...
...
#Autowired
TicketConsoleGTRDao ticketConsoleGTRDao;
private static final Logger LOGGER = Logger.getLogger(CreateInfoTravailPageBean.class);
public String viewInfoTravail() {
populateTypeInfoTravailList();
...
...
return NavigationConstants.PAGE_CREATE_INFO_TRAVAIL;
}
public String saveInfoTravail() {
String idIncident = getRequestParameterValue(TicketConstants.ID_INCIDENT);
infoTravail.setTicketId(idIncident);
infoTravail.setDate_creation(formatter.format(new Date()));
// HERE I WANT TO CALL ModifyCDSPageBean.viewTicketDetails() method
// pass id_incident as request parameter while making this call
// because if you check ModifyCDSPageBean.viewTicketDetails above it
// looks for request parameter id_incident
}
Re-reading your requirements, it sounds like you want a page initialization code. That is, turn around the flow and don't let entry-points into your page1 call the bean's code, let the bean do that itself:
#ManagedBean #RequestScoped
public class ModifyCDSPageBean {
#Inject #Param(name = TicketConstants.ID_INCIDENT)
private ParamValue<Long> myParam;
#Autowired
private TicketConsoleGTRDao dao;
private List<InfoTravail> travailsList;
#PostConstruct
public void init() {
if (myParam.getValue() != null) {
// do stuff based on the param being set
travailsList = dao.findById(myParam.getValue());
}
}
// getter for travailsList
}
And then include the parameter in your navigation from bean2:
public class Bean2 {
public String save() {
String idIncident = getRequestParameterValue(TicketConstants.ID_INCIDENT);
// do stuff and then return to page1, passing parameter ID_INCIDENT
return String.format("page1?faces-redirect=true&%s=%s",
TicketConstants.ID_INCIDENT, idIncident);
}
If you don't need to execute your view preparation code every time you create ModifyCDSPageBean (ie, if it's used on other pages, too), look into calling it on your page. If you've got JSF-2.2, try <f:viewAction action="#{modifyCDSPageBean.init}"> or on older versions, <f:event listener="#{modifyCDSPageBean.init()}" type="preRenderView">.
Note that #PostConstruct with a #RequestScoped bean will re-create the bean with each AJAX-request, which is probably not what you want. In that case, try #ViewScoped.
My code example uses omnifaces' #Param for my lack of knowledge of spring. Maybe they have something similar in the toolkit already (or just call your getRequestParameterValue from the bean method).
Is there a way to set a bean property from a Validator?
In my case, I have a validator which connects to the database and performs some validation.
Upon successful validation, I want to save the object received from database, inside a bean property.
Currently i'm doing this by setting a static property of my bean from the validator.
Here is my validator method
public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException {
//perform validation
if(isValidated) {
Referral ref = database.getReferral(value.toString()); //receive referral object from batabase
RegistrationBean.staticReferral = ref; // Set ref to RegistrationBean's static property
} else {
FacesMessage msg = new FacesMessage(FacesMessage.SEVERITY_FATAL, "Invalid Referral!", "Referral does not exist!");
throw new ValidatorException(msg);
}
}
and here is my RegistrationBean
#ManagedBean
#ViewScoped
public class RegistrationBean implements Serializable {
//other bean properties
private Referral referral;
public static Referral staticReferral;
public RegistrationBean() {
//default constructor
}
public Referral getReferral() {
this.staticReferral = referral;
return referral;
}
// other getters, setters and methods
}
So the questions in my mind are:
Is there a way to set a bean property directly from a bean? (without
using a static property)
Would there be any concurrency issues (one user may receive other user's selected referral object etc) using the existing approach?
Thanks
Static members in managed beans are shared among all instances (and users of your application). So think at least twice before making a member variable static.
If you make your validator a managed bean, you can inject your target managed bean into your validator. See this answer for details.
In the given example an EJB is injected, but you can inject a JSF managed bean via the #ManagedProperty annotation
I have the following construct at several places in my webapp in order to conditionally render page fragments depending on some actions:
<h:panelGroup rendered="#{managedBean.serviceSelected == 'insurance'}">
<ui:include src="/pages/edocket/include/service1.xhtml" />
</h:panelGroup>
I have observed, that the <ui:include> is still executed even when the rendered attribute evaluates false. This unnecessarily creates all backing beans associated with the service1.xhtml file which is been included.
How can I skip executing the <ui:include> when the parent UI component is not rendered, so that all those backing beans are not unnecessarily created?
Unfortunately, this is by design. The <ui:include> runs as being a taghandler during the view build time, while the rendered attribute is evaluated during the view render time. This can be better understood by carefully reading this answer and substituting "JSTL" with "<ui:include>": JSTL in JSF2 Facelets... makes sense?
There are several ways to solve this, depending on the concrete functional requirement:
Use a view build time tag like <c:if> instead of <h:panelGroup>. This however puts implications into the #{managedBean}. It can't be view scoped and should do its job based on HTTP request parameters. Exactly those HTTP request parameters should also be retained in subsequent request (by e.g. <f:param>, includeViewParams, etc) so that it doesn't break when the view is restored.
Replace <ui:include> by a custom UIComponent which invokes FaceletContext#includeFacelet() during the UIComponent#encodechildren() method. So far no such component exist in any of the existing libraries. But I can tell that I've already such one in mind as a future addition for OmniFaces and it works as intuitively expected here at my test environment (with Mojarra). Here's a kickoff example:
#FacesComponent(Include.COMPONENT_TYPE)
public class Include extends UIComponentBase {
public static final String COMPONENT_TYPE = "com.example.Include";
public static final String COMPONENT_FAMILY = "com.example.Output";
private enum PropertyKeys {
src;
}
#Override
public String getFamily() {
return COMPONENT_FAMILY;
}
#Override
public boolean getRendersChildren() {
return true;
}
#Override
public void encodeChildren(FacesContext context) throws IOException {
getChildren().clear();
FaceletContext faceletContext = ((FaceletContext) context.getAttributes().get(FaceletContext.FACELET_CONTEXT_KEY));
faceletContext.includeFacelet(this, getSrc());
super.encodeChildren(context);
}
public String getSrc() {
return (String) getStateHelper().eval(PropertyKeys.src);
}
public void setSrc(String src) {
getStateHelper().put(PropertyKeys.src, src);
}
}
Use conditional expression as ui:include src:
<h:panelGroup>
<ui:include
src="#{managedBean.serviceSelected == 'insurance' ?
'/pages/edocket/include/service1.xhtml'
:
'/pages/empty.xhtml'}"
/>
</h:panelGroup>
I'm developing a plugin to display additional information related to a project.
So I'm developing a Project Tab Panel module but my page does not display the paramenters I put in the velocity context.
Here is the a part of plugin xml:
<project-tabpanel key="stats-tab-panel" name="Stats Tab Panel" i18n-name-key="stats-tab-panel.name" class="it.pride.jira.plugins.StatsTabPanel">
<description key="stats-tab-panel.description">The Stats Tab Panel Plugin</description>
<label key="stats-tab-panel.label"></label>
<order>10</order>
<resource type="velocity" name="view" location="templates/tabpanels/stats-tab-panel.vm"/>
Here instead the useful part of my class:
public class StatsTabPanel extends GenericProjectTabPanel {
public StatsTabPanel(JiraAuthenticationContext jiraAuthenticationContext,
FieldVisibilityManager fieldVisibilityManager) {
super(jiraAuthenticationContext, fieldVisibilityManager);
// TODO Auto-generated constructor stub
}
public String testvalue="112002";
#Override
public boolean showPanel(BrowseContext context){
return true;
}
#Override
public Map<String, Object> createVelocityParams (BrowseContext context) {
Map<String, Object> contextMap = createVelocityParams(context);
contextMap.put("testvalue", testvalue);
return contextMap;
}
}
So, as in this case, when i write `$testvalue in my template the number doesn't show up.
What am I doing wrong?
The problem is that the getHtml method that is used to return the HTML for the tab has a Map that is the Velocity context but only contains the params in the BrowseContext object. The way to fix this is to override createVelocityParams in your class, e.g.
protected Map createVelocityParams(final BrowseContext ctx) {
Map params = super.createVelocityParams(ctx);
params.put("myparam", "some value for it");
return params;
}
The problem is that method is protected so I ended up also overriding getHtml which calls createVelocityParams in a parent class.
Some Project tabs extend GenericProjectTabPanel but some such as SummaryProjectTabPanel.java seem to use UI Fragments. I suspect that Fragments is what things are moving towards.