I would like to pass an value to a managed bean under the hood. So I have this managed bean:
#ManagedBean(name = "mbWorkOrderController")
#SessionScoped
public class WorkOrderController {
// more attributes...
private WorkOrder workOrderCurrent;
// more code here...
public WorkOrder getWorkOrderCurrent() {
return workOrderCurrent;
}
public void setWorkOrderCurrent(WorkOrder workOrderCurrent) {
this.workOrderCurrent = workOrderCurrent;
}
}
It holds a parameter workOrderCurrent of the custom type WorkOrder. The class WorkOrder has an attribute applicant of type String.
At the moment I am using a placeholder inside my inputtext to show the user, what he needs to type inside an inputText.
<p:inputText id="applicant"
value="#{mbWorkOrderController.workOrderCurrent.applicant}"
required="true" maxlength="6"
placeholder="#{mbUserController.userLoggedIn.username}" />
What I want to do, is to automatically pass the value of mbUserController.userLoggedIn.username to mbWorkOrderController.workOrderCurrent.applicant and remove the inputText for applicant completely from my form.
I tried to use c:set:
<c:set value="#{mbUserController.userLoggedIn.username}" target="#{mbWorkOrderController}" property="workOrderCurrent.applicant" />
But unfortunatelly I get a javax.servlet.ServletException with the message:
The class 'WorkOrderController' does not have the property 'workOrderCurrent.applicant'.
Does anybody have an advice?
The class 'WorkOrderController' does not have the property 'workOrderCurrent.applicant'.
Your <c:set> syntax is incorrect.
<c:set value="#{mbUserController.userLoggedIn.username}"
target="#{mbWorkOrderController}"
property="workOrderCurrent.applicant" />
You seem to be thinking that the part..
value="#{mbWorkOrderController.workOrderCurrent.applicant}"
..works under the covers as below:
WorkOrderCurrent workOrderCurrent = mbWorkOrderController.getWorkOrderCurrent();
workOrderCurrent.setApplicant(applicant);
mbWorkOrderController.setWorkOrderCurrent(workOrderCurrent);
This isn't true. It works under the covers as below:
mbWorkOrderController.getWorkOrderCurrent().setApplicant(applicant);
The correct <c:set> syntax is therefore as below:
<c:set value="#{mbUserController.userLoggedIn.username}"
target="#{mbWorkOrderController.workOrderCurrent}"
property="applicant" />
That said, all of this isn't the correct solution to the concrete problem you actually tried to solve. You should perform model prepopulating in the model itself. This can be achieved by using #ManagedProperty to reference another bean property and by using #PostConstruct to perform initialization based on it.
#ManagedBean(name = "mbWorkOrderController")
#SessionScoped
public class WorkOrderController {
#ManagedProperty("#{mbUserController.userLoggedIn}")
private User userLoggedIn;
#PostConstruct
public void init() {
workOrderCurrent.setApplicant(userLoggedIn.getUsername());
}
// ...
}
Perhaps you could explain the context a bit more, but here's another solution. If you're navigating from another page, you can pass some identifier of work WorkOrder in the URL, like this http://host:port/context/page.xhtml?workOrderId=1.
Then, you can set the identifier in the managed bean like this:
<h:html>
<f:viewParam name="workOrderId" value="#{mbWorkOrderController.id}"/>
</h:html>
You'll have to add a new property to your bean:
public class WorkOrderController {
private long id;
public long getId() { return id; }
public void setId(long id) { this.id = id; }
// ...
}
And then, after the property has been set by JSF, you can find the work order in a lifecycle event:
<h:html>
<f:viewParam name="workOrderId" value="#{mbWorkOrderController.id}"/>
<f:event type="preRenderView" listener="#{mbWorkOrderController.findWorkOrder()}"/>
</h:html>
public class WorkOrderController {
private long id;
public long getId() { return id; }
public void setId(long id) { this.id = id; }
public void findWorkOrder() {
this.workOrderCurrent = null /* some way of finding the work order */
}
// ...
}
This strategy has the advantage of letting you have bookmarkable URLs.
Related
Let's assume a simple Jsf example with a xhtml page, a ManagedBean, a service and an JPA entityClass. I have a lot of usecases with the following structure:
Hold an entity in my bean
Do actions on the entity
Do rendering on the updated entity
Some easy example, so everyone will understand
Entity:
public class Entity {
private long id;
private boolean value;
...
// Getter and Setter
}
Dao:
public class EntityService {
// Entity Manger em and other stuff
public void enableEntity(long id) {
Entity e = em.find(id);
e.value = true;
em.persist(e);
}
}
Managed Bean:
#ManagedBean
#RequestScoped/ViewScoped
public class EntityBean() {
#EJB
private EntityService entityService;
private Entity entity;
#PostConstruct
public void init() {
// here i fetch the data, to provide it for the getters and setters
entity = entityService.fetchEntity();
}
public void enableEntity() {
entityService.enableEntity(entity.getId);
}
// Getter and Setter
}
and finally a simple xhtml:
<html>
// bla bla bla
<h:panelGroup id="parent">
<h:panelGroup id="disabled" rendered="#{not EntityBean.entity.value}>
<p:commandButton value="action" action="#{EntityBean.enableEntity}" update="parent" />
</h:panelGroup>
<h:panelGroup id="enabled" rendered="#{EntityBean.entity.value}>
// other stuff that should become visible
</h:panelGroup>
</h:panelGroup>
</html>
What i want to achieve:
Always show the up to date entity in every request!
What i already tried
I tried with a dao-fetch in my getter. But you can read everywhere that this is bad practice, because jsf will call the getter more than once (but for now the only way i can keep them really up to date).
I tried RequestScoped Beans. But the Bean will be created before the action is done, and is not recreated on the update call and the value will be outdated (Makes sense, since this is one request, and the request starts with the click on the button).
I tried ViewScoped Beans and added an empty String return value to my method. My hope was, that this redirection will recreate the Bean after the action was processed. But this was not the case.
I tried to call the refetch function manually after every method i used. But I have some cross bean actions on the same entity (My real entities are way more complex than this example). So the different Beans do not always know, if and when the entity has changed.
My Questions:
Can this be done with any kind of Scope? Let's say that every request will fetch the data from my PostConstruct again.
There must be a better solution than the dao-fetch in the getter method
This seems to be a fundamental problem for me, because getting the up to date data is essential for my app (data is changed often).
Using Primefaces 6.1 and Wildfly 10.x
What do you think about this?
A request scoped bean which will be created for update, too and does only one fetchEntity() per request.
<f:metadata>
<f:viewAction action="#{entityBean.load()}" onPostback="true"/>
</f:metadata>
#ManagedBean
#RequestScoped
public class EntityBean() {
#EJB
private EntityService entityService;
private Entity entity = null;
public void load() {}
public Entity getEntity() {
if(entity == null) {
entity = entityService.fetchEntity();
}
return entity;
}
public void enableEntity() {
entityService.enableEntity(getEntity().getId);
}
// Getter and Setter
}
I added an <p:inputSwitch> in my JSF page, but this is not working.
Get and set method is not called when I change the stat
The JSF page :
<p:inputSwitch value="#{SystemController.statSystem}" />
The managed bean
#ManagedBean
#ViewScoped
public class SystemController extends AbstractController implements Serializable {
private Boolean statSystem;
public Boolean getStatSystem() {
return statSystem;
}
public void setStatSystem(Boolean statSystem) {
this.statSystem=statSystem;
}
I added an ajax tag and it works ! Get and Set methods are working now.
<p:inputSwitch value="#{SystemController.statSystem}" >
<p:ajax />
</p:inputSwitch>
Your statSystem variable is not initialized.
Init like:
private Boolean statSystem = false;
or instead change data type to primitive:
private boolean statSystem;
I want to access the property of a #SessionScoped bean in another bean using #ManagedProperty. In short, I want to access the name property of firstBean in secondBean.
#ManagedBean
#SessionScoped
public class FirstBean implements Serializable{
private String name;
//...other attributes
//...constructor
public String getSelectedModel() {
return selectedModel;
}
public void setSelectedModel(String selectedModel) {
this.selectedModel = selectedModel;
}
//other getters&setters
}
And second bean:
#ManagedBean
#SessionScoped
public class SecondBean implements Serializable{
#ManagedProperty(value="#{firstBean}")
private FirstBean firstBean
public SecondBean() {
System.out.println(firstBean.getName());
}
public IndexBean getFirstBean() {
return firstBean;
}
public void setFirstBean(FirstBean firstBean) {
this.firstBean = firstBean;
}
When I run this, I always get NullPointerException on System.out.println(firstBean.getName()); in the constructor of second bean, which seems to mean that I need to create a new instance of firstBean.
But strangely, when I commented out this line, I can do something like this with no errors, which means that firstBean is actually a property of secondBean.
<h:outputText value="#{secondBean.firstBean.name}" />
What's the problem here?
It's not possible to access an injected dependency in the constructor. You're basically expecting that Java is able to do something like this:
SecondBean secondBean; // Declare.
secondBean.firstBean = new FirstBean(); // Inject.
secondBean = new SecondBean(); // Construct.
It's absolutely not possible to set an instance variable if the instance is not constructed yet. Instead, it works as follows:
SecondBean secondBean; // Declare.
secondBean = new SecondBean(); // Construct.
secondBean.firstBean = new FirstBean(); // Inject.
Then, in order to perform business actions based on injected dependencies, use a method annotated with #PostConstruct. It will be invoked by the dependency injection manager directly after construction and dependency injection.
So, just replace
public SecondBean() {
System.out.println(firstBean.getName());
}
by
#PostConstruct
public void init() { // Note: method name is fully to your choice.
System.out.println(firstBean.getName());
}
What is the difference between using value and binding with JavaServer Faces, and when would you use one as opposed to the other? To make it clearer what my question is, a couple of simple examples are given here.
Normally with JSF in the XHTML code you would use "value" as here:
<h:form>
<h:inputText value="#{hello.inputText}"/>
<h:commandButton value="Click Me!" action="#{hello.action}"/>
<h:outputText value="#{hello.outputText}"/>
</h:form>
Then the bean is:
// Imports
#ManagedBean(name="hello")
#RequestScoped
public class Hello implements Serializable {
private String inputText;
private String outputText;
public void setInputText(String inputText) {
this.inputText = inputText;
}
public String getInputText() {
return inputText;
}
// Other getters and setters etc.
// Other methods etc.
public String action() {
// Do other things
return "success";
}
}
However, when using "binding", the XHTML code is:
<h:form>
<h:inputText binding="#{backing_hello.inputText}"/>
<h:commandButton value="Click Me!" action="#{backing_hello.action}"/>
<h:outputText value="Hello!" binding="#{backing_hello.outputText}"/>
</h:form>
and the correspondibg bean is called a backing bean, and is here:
// Imports
#ManagedBean(name="backing_hello")
#RequestScoped
public class Hello implements Serializable {
private HtmlInputText inputText;
private HtmlOutputText outputText;
public void setInputText(HtmlInputText inputText) {
this.inputText = inputText;
}
public HtmlInputText getInputText() {
return inputText;
}
// Other getters and setters etc.
// Other methods etc.
public String action() {
// Do other things
return "success";
}
}
What practical differences are there between the two systems, and when would you use a backing bean rather than a regular bean? Is it possible to use both?
I have been confused about this for some time, and would most appreciate having this cleared up.
value attribute represents the value of the component. It is the text that you see inside your text box when you open the page in browser.
binding attribute is used to bind your component to a bean property. For an example in your code your inputText component is bound to the bean like this.
#{backing_hello.inputText}`
It means that you can access the whole component and all its properties in your code as a UIComponent object. You can do lot of works with the component because now it is available in your java code.
For an example you can change its style like this.
public HtmlInputText getInputText() {
inputText.setStyle("color:red");
return inputText;
}
Or simply to disable the component according to a bean property
if(someBoolean) {
inputText.setDisabled(true);
}
and so on....
Sometimes we don't really need to apply the value of UIComponent to a bean property. For example you might need to access the UIComponent and work with it without applying its value to the model property. In such cases it's good to use a backing bean rather than a regular bean. On the other hand in some situations we might need to work with the values of the UIComponent without any need of programmatic access to them. In this case you can just go with the regular beans.
So, the rule is that use a backing bean only when you need programmatic access to the components declared in the view. In other cases use the regular beans.
I'm trying to wrap my head around some basic JSF 2 concepts. For instance, if I have a managed bean, Bean1:
#ManagedBean
public class Bean1 {
private String foo;
private String bar;
}
and the values for foo and bar are obtained from a JSF web form. On each submit of the web form, I want to store an instance of Bean1 in a Java Collection of another bean:
#ManagedBean
public class Bean2 {
private List<Bean1> beanList;
}
What is the correct way to achieve this? Thanks.
BalusC is 100% per cent right, but (as he warns) his answer will be useless. The important point here is that you do not need nor want the second bean to be managed at all. It is your model, not your GUI. You probably wanted something like:
#ManagedBean
#ViewScoped
class PeopleHolder {
private List<Person> people = new ArrayList<Person>();
// not managed at all:
private Person currentPerson;
// just the getter, no need for a setter
public Person getCurrentPerson() { return currentPerson; }
#PostConstruct
public init(){ currentPerson = new Person(); }
public void addCurrentPersonToList() {
people.add(currentPerson);
init();
}
// just for test:
public List<People> getPeople() { return people; }
}
and now a form:
<h:form>
<h:inputText value="#{peopleHolder.currentPerson.name}" />
<h:inputText value="#{peopleHolder.currentPerson.lastName}" />
<h:commandButton action="#{peopleHolder.addCurrentPersonToList}" />
</h:form>
Make Bean2 a managed property of Bean1 so that you have access to its beanList property.
#ManagedBean
public class Bean1 {
private String foo;
private String bar;
#ManagedProperty("#{bean2}")
private Bean2 bean2;
public void submit() {
bean2.getBeanList().add(this);
// ...
}
// ...
}
(please note that this way just the reference is stored, not a clone of the Bean1's state or something!)
Needless to say that this is a design smell. There are likely better ways to achieve the concrete functional requirement which you've had in mind while asking the question but didn't tell anything about. In the future try to ask how to solve the functional requirement instead of how to achieve a solution (which may not be the right solution after all).