Hey guys. I'm designing a site that uses the Icefaces framework. I've been reading a book called Real World Java EE patterns. I'm kind of confused how to layout the pages. Normally I would have just a POJO class implement serializable for a bean. This bean would then back each page. With a single page design I'm going to have a bunch of elements on the page. Datatables, trees, inputs, calendars etc. Is it normal or best practice to have separate beans for each datatable, calendar, etc or put that all in one bean? I'm not sure how to approach this. Right now each element is a bean and I'm using the #Inject annotation to have the data table talk to the tree and vise versa. This creates really bad code and if I put this as a member of the class I will get a circular reference because the data table bean has to inject the calendar and the calendar has to inject the data table.
Thanks for any help.
I tend to use a single bean per <h:form> or at least per view (XHTML/JSP file). Any related beans will just be injected in this particular "main" bean (and thus not among each other).
Related
I have been reading about JSF navigation between pages in an application and I am still a little bit confused. I have a small web application with a series of pages with continue and previous buttons on each page. To save the valid data entered on the view, I am trying to figure out ways to make the valid form data stick when the user goes back and forward. Initially, I had the page views in session scope but I understood that its bad practice. The data that I am capturing can be a managed bean with composite objects within the bean that corresponds to the data that is captured in the pages. But, I read that managed bean in session is not a good idea either. After reading through so many posts, I feel that I should know the solution but its still not very clear as to how to save the validated data into JSF so that it displays when the user navigates back and forth? Appreciate your help.
Seems to me you're trying to accomplish some kind of wizard-like navigation. For this use-case I would suggest the use of a #ConversationScoped backend Bean.
This scope is not provided by the JSF- but by the CDI-framework which just work perfectly together.
To get this to work you essentially have to follow these steps:
Create a CDI Bean like:
#Named
#ConversationScoped
public class MyBean implements Serializable {
#Inject
private Conversation conversation;
...
}
#Named is the CDI alternative to JSFs #ManagedBean.
Your class should implement the Serializable interface to be able to passivate its state.
CDI #Inject the Conversation-object to use in your code.
Start the conversation anywhere inside your code via:
conversation.start();
Do your magic: process input, change data, navigate, persist to db,...
End the conversation (in your case at the last page, maybe after a click on a 'Finish'-Button)
conversation.end();
A quick google search came up with this pretty tutorial implementing a questionaire site which could be useful to you. Have a look at this.
Hope this helps. Have fun!
Are you not persisting the data to a database? If so, you can use a request-scoped managed bean, that way when you navigate back to the original page the updated records will be re-retrieved from the database and your changes will be displayed.
I recently read this article from Neil Griffin Making Distinctions Between Different Kinds of JSF Managed-Beans and it got me thinking about the distinction between different beans in my own application. To quickly summarise the gist:
Model Managed-Bean: This type of managed-bean participates in the
"Model" concern of the MVC design pattern. When you see the word
"model" -- think DATA. A JSF model-bean should be a POJO that follows
the JavaBean design pattern with getters/setters encapsulating
properties.
Backing Managed-Bean: This type of managed-bean participates in the
"View" concern of the MVC design pattern. The purpose of a
backing-bean is to support UI logic, and has a 1::1 relationship with
a JSF view, or a JSF form in a Facelet composition. Although it
typically has JavaBean-style properties with associated
getters/setters, these are properties of the View -- not of the
underlying application data model. JSF backing-beans may also have JSF
actionListener and valueChangeListener methods.
Controller Managed-Bean: This type of managed-bean participates in
the "Controller" concern of the MVC design pattern. The purpose of a
controller bean is to execute some kind of business logic and return a
navigation outcome to the JSF navigation-handler. JSF controller-beans
typically have JSF action methods (and not actionListener methods).
Support Managed-Bean: This type of bean "supports" one or more views
in the "View" concern of the MVC design pattern. The typical use case
is supplying an ArrayList to JSF h:selectOneMenu drop-down
lists that appear in more than one JSF view. If the data in the
dropdown lists is particular to the user, then the bean would be kept
in session scope.
Utility Managed-Bean: This type of bean provides some type of
"utility" function to one or more JSF views. A good example of this
might be a FileUpload bean that can be reused in multiple web
applications.
This made sense to me and for the past few hours I have been refactoring my code and came up with the following with respect to the user login:
The AuthenticationController is an example of a Controller Managed-Bean. It is request-scoped and features two getters and setters for setting a username and password, and two navigation methods, authenticate and logout, navigating the user to either their private area upon successful login, or back to the main page when logging out.
The UserBean is an example of a Support Managed-Bean. It is session-scoped and features an instance of User class (which would be null when you are not authenticated) with a getter and setter, nothing more.
The AuthenticationController has this user as a managed property (#ManagedProperty(value = "#{userController.user} private User user;). Upon successful authentication, the AuthenticationController would set the managed property to the actual user instance with the corresponding username that was used for the login.
Any new beans would be able to grab the user as a managed property as well and pull the data they need, such as group membership for instance, if the User class would feature a list with group names.
Would this way be the proper way to go about with regard to the seperation of concerns?
This is a very subjective question. I personally disagree that article and find that it's giving really bad advice to starters.
Model Managed-Bean: This type of managed-bean participates in the "Model" concern of the MVC design pattern. When you see the word "model" -- think DATA. A JSF model-bean should be a POJO that follows the JavaBean design pattern with getters/setters encapsulating properties.
I would absolutely not make or call it a managed bean. Just make it a property of a #ManagedBean. For example a DTO or JPA #Entity.
Backing Managed-Bean: This type of managed-bean participates in the "View" concern of the MVC design pattern. The purpose of a backing-bean is to support UI logic, and has a 1::1 relationship with a JSF view, or a JSF form in a Facelet composition. Although it typically has JavaBean-style properties with associated getters/setters, these are properties of the View -- not of the underlying application data model. JSF backing-beans may also have JSF actionListener and valueChangeListener methods.
This way you keep duplicating and mapping the properties of the entity in the managed bean. This makes no sense to me. As said, just make the entity a property of the managed bean and let the input fields refer it directly like #{authenticator.user.name} instead of #{authenticator.username}.
Controller Managed-Bean: This type of managed-bean participates in the "Controller" concern of the MVC design pattern. The purpose of a controller bean is to execute some kind of business logic and return a navigation outcome to the JSF navigation-handler. JSF controller-beans typically have JSF action methods (and not actionListener methods).
This describes the #RequestScoped/#ViewScoped #ManagedBean class pretty much. Whether event listener methods are allowed or not depends on whether they are specific to the view which is tied to the bean and/or are for their job dependent on the bean's state. If they are, then they belongs in the bean. If not, then they should be a standalone implementation of any FacesListener interface, but definitely not a managed bean.
Support Managed-Bean: This type of bean "supports" one or more views in the "View" concern of the MVC design pattern. The typical use case is supplying an ArrayList to JSF h:selectOneMenu drop-down lists that appear in more than one JSF view. If the data in the dropdown lists is particular to the user, then the bean would be kept in session scope.
Fine. For application wide data like dropdown lists just use an #ApplicationScoped bean and for session wide data like logged-in user and its preferences just use a #SessionScoped one.
Utility Managed-Bean: This type of bean provides some type of "utility" function to one or more JSF views. A good example of this might be a FileUpload bean that can be reused in multiple web applications.
This makes not really sense to me. Backing beans are usually tied to single views. This sounds too much like an ActionListener implementation which is to be used by <f:actionListener> in command components to your choice. Definitely not a managed bean.
For kickoff examples of the right approach, see also:
Hello World example in Our JSF wiki page
"Bookstore CRUD" example in this answer
"Master-detail" example in this answer
JSF Service Layer
Communication in JSF 2
I have three screens(views) associated with separate managed beans for each view.
And, I have a common pop-up dialog which can be opened in all the views.
Can I define a managedbean separately for the pop-up with state #NoneScoped; and maintain an instance of it in each parent bean?? or
Do I need to maintain pop-up data in all three parent views?
Please, suggest me the best practice.
I think this is what you are looking for (check out the answer by BalusC) -
Whats the correct way to create multiple instances of managed beans in JSF 2.0
And since you are using #NoneScoped (unlike #RequestScoped in the above question), I also recommend you to look at this answer by BalusC (about #NoneScoped) -
what is none scope bean and when to use it?
And according to this answer, you can't maintain any instances of a managedbean that is none-scoped, as they are garbaged as soon as they are used.
So, in your case since you have three separate views, for each view, the bean is constructed and used to build the view and garbaged. (Looks like it does not even last for a request cycle). When you request another view, it will be a separate instance.
To have multiple intances of a bean, you can have three properties in a Session-Scoped been (to make them survive across multiple views).
#ManagedBean
#SessionScoped
public class Parent {
private Child child1;
private Child child2;
private Child child3;
// ...
}
The scenario is the following:
A managed bean uses as attributes another managed bean, like customerBean.current.customerAgreement. When I display the data on a pge the expression #{customerBean.current.customerAgreement.agreementTitle} is filled and shows the expected output.
However in an inputText the value is only changed on the screen, not in the value I get back in the managedBean. Is there a limitation on how deep such a structure can be constructed?
No, there is basically no limitation in how deep you can nest beans.
Your problem is caused by something else. Perhaps you are not preserving the same parent beans in the request of the form submit as it was during the request of the form display. Hard to tell without further detail about your code. All what I can suggest is to try making CustomerBean a view scoped bean.
Im currently using JSF2, and i notice the JSF bean could have a lot of responsibility, and if combined will look like lots of codes. These include :
holding the state / data
could be a backing bean for the UI component
action methods definition
action listener methods definition
navigation
calling the services
all the setter n getters
Does it make anysense to break these into several classes or do you usually combine all of them together ?
Currenly for every JSF Bean, i define another class to hold the view data / state along with the setter getters.
How do you usually do it ? Please share your experience !
Thank you =)
Every property which is been used in action(listener) methods needs to stay in the backing bean. The remnant most likely belongs in its own class which can in turn be a different (managed/entity)bean, eventually as a (managed)property of the bean where it originated.