jsf jsf-2 seam-conversation conversation-scope

How does JSF 2 ConversationScope work?

I have a JSF facelets page that displays a table of data depending on which page they are viewing. When I display page 1, I call the view() action method to get the data from the database for both pages and store it as a private member field of the bean (two arrays). I also call conversation.start() on the injected conversation instance in the view() method.

When the user clicks the "next" button (h:commandButton) to go to page 2, I am executing a next() method to update the backing bean to point to array 2 so it will print out its contents. The problem is, array 2 no longer exists. I don't know why I am losing conversation scope. Any ideas?

//tells the object which page we are on, and thus what data to display.
private int part = 1; 

// These arrays are filled with data but conversation scope doesn't 
// keep them on the next postback.
private int[] part1 = new int[15], part2 = new int[15];

Solution

You should paste some more code so we can help you better. From what you say i cannot see where you called the method for ending the conversation(You need that too when working with conversation scope).

I will paste here a little example that i think will help you understand how conversation scope works:

This is the start page of a wizard(Conversation scope is great for wizards)

<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:f="http://java.sun.com/jsf/core">

<h:head>
    <title>ConversationScoped demo CDI(Component Dependency
    Injection)</title>
</h:head>

<h:body>



    <h3>ConversationScoped demo CDI(Component Dependency Injection)</h3>

    <p>A conversation scope provides persistence until a goal is
    reached<br />
    In this example the first entered value will remain until the end
    method is called<br />
    in some page.<br />
    This is a really useful gadget, for making registration wizards and
    similar tools...</p>

    <h:form>
        <h:outputText value="Type something" />
        <h:inputText value="#{ supportBB.someValue}" />
        <h:commandButton value="continue" action="#{ supportBB.onClick}" />
    </h:form>

</h:body>
</html>

This is the second page of the wizard

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:f="http://java.sun.com/jsf/core">

<h:head>
    <title>ConversationScoped demo CDI(Component Dependency
    Injection)</title>
</h:head>

<h:body>



    <h3>This is the next page(The value is saved in the conversation)</h3>

        <h4><h:outputText value="#{ supportBB.someValue}"/></h4>

    <h:form>        
        <h:commandButton value="Finish conversation" action="#{ supportBB.onKeepGoing}"/>
    </h:form>

</h:body>
</html>

And this is the page where the scope ends

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:f="http://java.sun.com/jsf/core">

<h:head>
    <title>ConversationScoped demo CDI(Component Dependency
    Injection)</title>
</h:head>

<h:body>



    <h3>This is the last page.The value still saved in conversation(until the end() method is called)</h3>

    <h4><h:outputText value="#{ supportBB.someValue}" /></h4>

    <h:form>
        <h:outputText
            value="Click finish to end the conversation(So saved values are disposed)" />
        <h:commandButton value="Finish" action="#{ supportBB.onFinish}" />
    </h:form>

</h:body>
</html>

Here the @ConversationScoped backing bean that starts and ends the conversation

package backingbeans;

import java.io.Serializable;

import javax.enterprise.context.Conversation;
import javax.enterprise.context.ConversationScoped;
import javax.inject.Inject;
import javax.inject.Named;

@Named()
@ConversationScoped()
public class SupportBB implements Serializable {
    private static final long serialVersionUID = 1L;
    private String someValue;
    @Inject
    private Conversation conversation;

    // Control start and end of conversation
    public void start() {
        conversation.begin();
    }

    public void end() {
        conversation.end();
    }

    // Navigation
    public String onClick() {
        if(someValue.equals("") || conversation == null) {
            return "";//Dont go anywhere if the there was no input the field
        }
        start();
        return "nextpage?faces-redirect=true";
    }

public String onKeepGoing() {
    return "finish?faces-redirect=true";
}

public String onFinish() {
    end();// If triggered when there is no conversation(i.e URL Navigation)
            // there will be an exception
    return "index?faces-redirect=true";
}

// Getters & Setters
public String getSomeValue() {
    return someValue;
}

public void setSomeValue(String someValue) {
    this.someValue = someValue;
}

}

I think this example is very simple and can help you understand how it works. Ask if you don't understand something

NOTE:

I think but i am not sure at 100% but ConversationScope only works if the backing bean is a CDI bean. This mean uses the annotation @Named. Better double check that.