RE: JSF Lifecycle and Design Question

[CONNER, BRENDAN \(SBCSI\)]

Title: Message

If this is *really* your first page, you can do something like:

 

<meta http-equiv="Refresh" content= "0; URL="">

 

that references an "outcome" that leads to a page that does an onload event that simulates the clicking of a hidden commandLink.  We've done something similar when we want to display a page that says "Working.... please wait" while executing an action that takes a long time.

 

- Brendan

 

-----Original Message-----
From: CONNER, BRENDAN (SBCSI)
Sent: Wednesday, March 01, 2006 3:51 PM
To: MyFaces Discussion
Subject: RE: JSF Lifecycle and Design Question

So this is, in effect on your index page?  No login page or anything?

 

- Brendan

 

-----Original Message-----
From: j2ee Developer [mailto:[EMAIL PROTECTED]
Sent: Wednesday, March 01, 2006 3:44 PM
To: MyFaces Discussion
Subject: Re: JSF Lifecycle and Design Question

Appreciate your response. That is very close to the way we have implemented it here. The only distinction being that the first time page load, in our scenario does not come from an action event ( commandbutton or commandlink). It is the first request. So I am confused as to where do I call the load(), other than the constructor.
 I understand that probably Shale or Spring can provide us this flexibility, but we are not evaluating them right now. Does anyone has any idea how I could implement this.

On 3/1/06, CONNER, BRENDAN (SBCSI) <[EMAIL PROTECTED]> wrote:

Oh, and don't forget to put the following tag in your JSP that displays the contents of your data bean:

 

<t:saveState value="#{myDataBean}"/>

 

- Brendan

 

-----Original Message-----
From: CONNER, BRENDAN (SBCSI)

Sent: Wednesday, March 01, 2006 2:18 PM
To: MyFaces Discussion
Subject: RE: JSF Lifecycle and Design Question

What we do is something like the following:

 

public class MyDataBean implements Serializable {

    private String field1;

    private Date field2;

    // define getters and setters

}

 

public class MyActionBean implements Serializable {

    public MyDataBean myDataBean;

    // define getter and setter for myDataBean

    public String loadData() {

        ...

        return outcome;

    }

 

    public Stirng saveData() {

        ...

        return outcome;

    }

    ...

}

 

And then define the following relationship in faces-config.xml:

 

 <managed-bean>
  <managed-bean-name>myDataBean</managed-bean-name>
  <managed-bean-classcom.example.MyDataBean</managed-bean-class>
  <managed-bean-scope>request</managed-bean-scope>
 </managed-bean>
 
 <managed-bean>
  <managed-bean-name>myActionBean</managed-bean-name>
  <managed-bean-class> com.example.MyActionBean</managed-bean-class>
  <managed-bean-scope>request</managed-bean-scope>
  <managed-property>
   <property-name>mydataBean</property-name>
   <value>#{myDataBean}</value>
  </managed-property>
 </managed-bean>

   

Then in the screen that leads up to the screen that displays the initial value of the bean, your commandButton or commandLink would invoke #{myActionBean.loadData}.  The "save" commandButton would invoke #{myActionBean.saveData}, whose "success" would just lead to redisplaying the page.

 

MyActionBean.loadData() would call the EJB layer to fetch the data and populate the fields within the object returned by getMyDataBean().  (JSF makes sure that this object is already instantiated.)

 

MyActionBean.saveData() would call the EJB layer to update the database with the contents of the object returned by getMyDataBean().  (JSF populates this bean with the contents of the request.)  After this method return, JSF automatically populates the HTML fields with the values of this bean.

 

- Brendan

-----Original Message-----
From: j2ee Developer [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, March 01, 2006 1:50 PM
To: MyFaces Discussion
Subject: Re: JSF Lifecycle and Design Question

Thanks  Brendan! Sounds interesting! Can you please explain a little bit more on how are you seperating data beans from action beans. This is how I have implemented my backing beans. All data is in a formbean(struts style formbean), this formbean is a member attribute of my actual backing bean. The actual backing bean just has the action methods like save, clear, delete etc.
Also if I do not call the action methods in the constructor, where do I call the action method before the screen gets displayed?

On 3/1/06, CONNER, BRENDAN (SBCSI) <[EMAIL PROTECTED]> wrote:

Also, you shouldn't have to worry about populating the bean's values again after the save (unless you're changing them or re-querying the database), since the beans already have their values.  From what I recall (although it's been awhile since I've worked with Struts), this is one of the areas in which JSF makes our life a lot easier than with Struts.

 

You may want to use <t:saveState>, though, to make sure your bean values get passed from one request to another.

 

- Brendan

-----Original Message-----
From: CONNER, BRENDAN (SBCSI)
Sent: Wednesday, March 01, 2006 12:59 PM
To: MyFaces Discussion
Subject: RE: JSF Lifecycle and Design Question

I would advise against doing any kind of action as part of a managed bean's constructor.  In my experience, you want to separate out Action methods from Managed Bean data.  Your action methods should be the only things accessing the EJBs, etc.  So you should have an action method that gets invoked before the screen is displayed.  It goes out and gets the data and populates the data fields, which then get displayed.  Your Save then is very simple, since JSF automatically populates your bean values (at least on simple screens).  Your "save" method then just has to refer to the bean values when calling the back end to save the data.

 

In our applications, we make the distinction between Actions and Data very concrete in that we have Action managed beans that are separate from Data managed beans.  This helps keep the developers on the right track, although the same thing can be accomplished by having Action methods and data accessors within the same bean.

 

- Brendan

 

-----Original Message-----
From: j2ee Developer [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, March 01, 2006 12:31 PM
To: users@myfaces.apache.org
Subject: JSF Lifecycle and Design Question

I have JSF lifecycle and design question. I am building a prototype, porting an existing Struts based application to JSF. The issue I am facing is I believe related to the JSF lifecycle, I need input from you folks as to whether what I am doing is the right way.

Here is the scenario of my application -

I have a page with a form with values populated from the database. The end user makes changes to the fields, and presses the commandbutton save. The values are saved to the database and the same page presented again with the new saved values.

Here is how I have implemented it -

The constructor of the backing bean makes the call to the model layer ( eventually EJB's), gets the initial data and displays it to the page. After user makes the changes, on pressing the commandbutton, the event handler, makes a call to the modellayer for saving the new data. After the save I populate the backing bean attributes with the new values, and display the same page again. All my backing beans are request scope ( and that's how I want them). I am using Myfaces implementation, and myfaces components.

Here is the problem I face -

The issue I am facing is that on calling save, or any other event, the constructor is called again . So eventually it ends up that there are double calls to the modellayer/database than what is required.

Is the way I am populating my backing beans wrong? Or is this the only way JSF handles things. Any input would be appreciated.