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I've read about all the differences between the types of scope (@SessionScoped, @ViewScoped, @ApplicationScope and @RequestScope), however, I'm still facing somehow a problem with my application. I have a page-1 with a grid and I send the selected item to a page-2(both page-1 and page-2 are using the same backing bean) to be edited and then persisted. My managed bean was using @RequestScoped from javax.faces.bean.RequestScoped as I've understood it was the ideal scope to use but it didn't work, the bean was being destroyed and the data was getting lost.

Resuming the story, I've changed the annotation to @SessionScoped and it worked but I would like to know if it is a good practice or not? Because I've read that it is not a good practice to use @SessionScoped as the data will be kept alive until the client logout.

Tarik
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pedroct92
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  • In a nutshell, the scenario you mentioned is fully transparently dependent upon the business requirements which scope to use/choose when. – Tiny Mar 07 '15 at 06:40

1 Answers1

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The best practice is to choose the appropriate bean scope (either session scope or another one). The appropriate scope to choose in your case is the @SessionScoped bean, because in case of:

  • RequestScoped: A new bean will be created after each HTTP request-response cycle, which you already encountered when you tried the request scope:

    the bean was being destroyed and the data was getting lost

  • ViewScoped: A new bean will be created once you navigate to another page (page-2 in your case)

    NB: A new bean will be also created each time you interact with the same page using a return value different than void or null.

  • @ApplicationScoped: Simply doesn't make any sense in that example (use it only when you want to share data/state between all users)

I strongly recommand you to take a look at this Q/A: How to choose the right bean scope? which provides detailled explanation on how to properly choose your beans scopes.

Other suggestions could be considered, which depends on your functionnal requirements, and / or application environment:

  1. As you are using the same bean within both pages, you can considere using one single JSF page and make use of the rendered attributes, then you can annotate your bean as @ViewScoped (In that case, don't forget to return void or null in your bean's action method). You may find some examples here: The benefits and pitfalls of @ViewScoped. Or,

  2. You can make use of the new Flash scope concept, an example could be found here: Understand Flash Scope in JSF2. Or,

  3. If your environment already support CDI (Or you can simply add the CDI support), then using @ConversationScoped would be the best choice regarding your case, you may find a good example here: How does JSF 2 ConversationScope work?. Or,

  4. Following Kukeltje's comment, you can use the @ViewAccessScoped or @GroupedConversationScoped provided by Apache DeltaSpike which are both more flexible than the std. @ConversationScoped.

Community
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Tarik
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  • I did not want to edit your reply directly, but I think the best scope in these cases is the [@ViewAccessScoped](http://deltaspike.apache.org/documentation/jsf.html#__viewaccessscoped) available in DeltaSpike. It is shorter than SessionScoped, longer than ViewScoped and compared to ConversationScoped it is 'automagically' maintained – Kukeltje Mar 06 '15 at 20:56
  • @Kukeltje Thanks for the infos, but I answered so, because the OP seems only talking about JSF scopes without any mention to CDI support or any other librairies. So as we don't really now the exact environment he is working in, I firstly suggested the appropriate bean to choose (in case he must only work with JSF scopes), then I provided additional suggestions in case he is not relying on JSF scopes only. Thus, using the `@ViewAccessScoped` is for me an additional suggestions if he want to use external libraries (BTW I didn't new about that scope, nice to learn additional informations) – Tarik Mar 06 '15 at 21:09
  • @Kukeltje updated with your suggestion – Tarik Mar 06 '15 at 21:20
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    you are right in that there are differences in jsf vs cdi scopes, but since the jsf ones should be considered deprecated, I think we should always mention the cdi ones. And btw, delta spike has more interesting things. Just like with OmniFaces, you should not work without it ;-) – Kukeltje Mar 06 '15 at 21:29
  • @Kukeltje Yes it contains very interesting modules, I'm still sticked on their documentation page – Tarik Mar 06 '15 at 21:35
  • Thanks guys for helping me out. For the moment, I will stick with @SessionScoped but I will take a deeper look into the other options. – pedroct92 Mar 09 '15 at 11:57