When i use
<h:button>
or
<h:link>
i can't make any business action in managed bean ?
Do I have to use
<h:form>
and
<h:commandButton>
or
<h:commandLink>
with action param or there is another solution ?
Depends on the kind of request you'd like to fire.
If it needs to be a non-idempotent POST request, just use <h:form> with <h:commandXxx action>. Again depending on the concrete functional requirement, you can render the results conditionally in the same view, or send a redirect to the target view afterwards.
If it needs to be an idempotent GET request, use <h:link>/<h:button> and perform the action in #PostConstruct method in the request/view scoped backing bean associated with the target page. If you need to pass parameters, use <f:param> to set them on <h:link>/<h:button> and use <f:viewParam> and <f:event type="preRenderView"> in target view to set and process them in backing bean associated with target view.
All in all, just use the right tool for the job as specified by concrete functional requirement (which you unfortunately didn't tell anything about in your question).
See also:
How to navigate in JSF? How to make URL reflect current page (and not previous one)
What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for?
Communication in JSF 2.0
No, you can't do that with h:link or h:button, there are meant to be bookmarkable GET urls. So if you want to perform business action, you need to use either commandButton or commandLink. Note that it's also worth to use h:outputLink for generating bookmarkable links between pages because is much more SEO friendly.
Related
When should I use an <h:outputLink> instead of an <h:commandLink>?
I understand that a commandLink generates an HTTP post; I'm guessing that outputLink will generate HTTP gets. That said, most of the JSF tutorial material I've read uses commandLink (almost?) exclusively.
Context: I am implementing a wee little demo project that shows a header link to a user page, much like Stack Overflow's...
...and I am not sure if commandLink (perhaps using ?faces-redirect=true for bookmarkability) or outputLink is the right choice.
The <h:outputLink> renders a fullworthy HTML <a> element with the proper URL in the href attribute which fires a bookmarkable GET request. It cannot directly invoke a managed bean action method.
<h:outputLink value="destination.xhtml">link text</h:outputLink>
The <h:commandLink> renders a HTML <a> element with an onclick script which submits a (hidden) POST form and can invoke a managed bean action method. It's also required to be placed inside a <h:form>.
<h:form>
<h:commandLink value="link text" action="destination" />
</h:form>
The ?faces-redirect=true parameter on the <h:commandLink>, which triggers a redirect after the POST (as per the Post-Redirect-Get pattern), only improves bookmarkability of the target page when the link is actually clicked (the URL won't be "one behind" anymore), but it doesn't change the href of the <a> element to be a fullworthy URL. It still remains #.
<h:form>
<h:commandLink value="link text" action="destination?faces-redirect=true" />
</h:form>
Since JSF 2.0, there's also the <h:link> which can take a view ID (a navigation case outcome) instead of an URL. It will generate a HTML <a> element as well with the proper URL in href.
<h:link value="link text" outcome="destination" />
So, if it's for pure and bookmarkable page-to-page navigation like the SO username link, then use <h:outputLink> or <h:link>. That's also better for SEO since bots usually doesn't cipher POST forms nor JS code. Also, UX will be improved as the pages are now bookmarkable and the URL is not "one behind" anymore.
When necessary, you can do the preprocessing job in the constructor or #PostConstruct of a #RequestScoped or #ViewScoped #ManagedBean which is attached to the destination page in question. You can make use of #ManagedProperty or <f:viewParam> to set GET parameters as bean properties.
See also:
ViewParam vs #ManagedProperty(value = "#{param.id}")
What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for?
Bookmarkability via View Parameters feature
How to navigate in JSF? How to make URL reflect current page (and not previous one)
I also see that the page loading (performance) takes a long time on using h:commandLink than h:link. h:link is faster compared to h:commandLink
I have a .xhtml model with a primeface datatable in it.
I call the page with an URL like this:
http://localhost:8080/myproject/mypage.jsf?Id=51&startDate=04-05-2015&name=whatever
The URL parameters are used to retrieve what will be displayed in the datatable, so it allow me to filter the content.
I used URL parameter because this page is displayed when I select a row in another datable so I have to make a manual redirect to this page on the baking bean.
However everytime I use one of primeface functionality like sorting or pagination primeface seems to do an ajax call to the backing bean but WITHOUT the parameters, so every object are displayed instead of a filtered list of Objects.
Therefore how can I force primefaces to use these parameters? Or how can I pass them to primefaces scope (they are #ManagedProperty on the backing bean)
The best and easiest way is to use the OmniFaces utility library and more specifically their <o:form>.
From the documentation:
The <o:form> is a component that extends the standard <h:form> and provides a way to keep view or request parameters in the request URL after a post-back
...
You can use it the same way as <h:form>, you only need to change h: to o:.
So, replace your <h:form> by either
<o:form includeRequestParams="true">
or
<o:form useRequestURI="true">
See also:
Retaining GET request query string parameters on JSF form submit
When should I use an <h:outputLink> instead of an <h:commandLink>?
I understand that a commandLink generates an HTTP post; I'm guessing that outputLink will generate HTTP gets. That said, most of the JSF tutorial material I've read uses commandLink (almost?) exclusively.
Context: I am implementing a wee little demo project that shows a header link to a user page, much like Stack Overflow's...
...and I am not sure if commandLink (perhaps using ?faces-redirect=true for bookmarkability) or outputLink is the right choice.
The <h:outputLink> renders a fullworthy HTML <a> element with the proper URL in the href attribute which fires a bookmarkable GET request. It cannot directly invoke a managed bean action method.
<h:outputLink value="destination.xhtml">link text</h:outputLink>
The <h:commandLink> renders a HTML <a> element with an onclick script which submits a (hidden) POST form and can invoke a managed bean action method. It's also required to be placed inside a <h:form>.
<h:form>
<h:commandLink value="link text" action="destination" />
</h:form>
The ?faces-redirect=true parameter on the <h:commandLink>, which triggers a redirect after the POST (as per the Post-Redirect-Get pattern), only improves bookmarkability of the target page when the link is actually clicked (the URL won't be "one behind" anymore), but it doesn't change the href of the <a> element to be a fullworthy URL. It still remains #.
<h:form>
<h:commandLink value="link text" action="destination?faces-redirect=true" />
</h:form>
Since JSF 2.0, there's also the <h:link> which can take a view ID (a navigation case outcome) instead of an URL. It will generate a HTML <a> element as well with the proper URL in href.
<h:link value="link text" outcome="destination" />
So, if it's for pure and bookmarkable page-to-page navigation like the SO username link, then use <h:outputLink> or <h:link>. That's also better for SEO since bots usually doesn't cipher POST forms nor JS code. Also, UX will be improved as the pages are now bookmarkable and the URL is not "one behind" anymore.
When necessary, you can do the preprocessing job in the constructor or #PostConstruct of a #RequestScoped or #ViewScoped #ManagedBean which is attached to the destination page in question. You can make use of #ManagedProperty or <f:viewParam> to set GET parameters as bean properties.
See also:
ViewParam vs #ManagedProperty(value = "#{param.id}")
What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for?
Bookmarkability via View Parameters feature
How to navigate in JSF? How to make URL reflect current page (and not previous one)
I also see that the page loading (performance) takes a long time on using h:commandLink than h:link. h:link is faster compared to h:commandLink
Is it possible to get a reference to the to-be-executed managedbean in the before-invokeApplication-phaselistener ?
Before the invoke application phase, it should be clear which managedBean that is going to execute the method.
For the sake of the example, assume there's 1 main manage bean to handle 1 jsf page.
So what i need is basically :
The user access the program from the menu
Because it's accessed from the menu, the main manage bean's init() method gets called to initialize stuffs like preparing data, doing authorization checks
Subsequent submits dont need to call the init() method anymore until it's reaccessed from the menu
To implement the point #2, im thinking of intercepting one of the phases
I've checked the API docs about getting the managed bean in the phases implementation, but i couldnt seem to find any.
After typing this question, i realize i could do this in #PostConstruct or the managed bean's constructor, but that would do only at the first time the bean is constructed, and my need is to call the method everytime the jsf is being accessed from the menu.
Any suggestions ?
Regards,
Albert Kam
You can access your managed beans via the ELContext/ELResolver. This is explained nicely in the MyFaces wiki (also works in vanilla JSF).
For example:
ELContext elContext = FacesContext.getCurrentInstance().getELContext();
NeededBean neededBean = (NeededBean) FacesContext.getCurrentInstance().getApplication()
.getELResolver().getValue(elContext, null, "neededBean");
See the MyFaces wiki entry for further explanation, and implementations for other JSF versions.
Your idea of using #PostConstruct is a good one. Consider changing your scope to something liked #ViewScoped, so the logic is executed everytime you navigate to that view.
Also, have a look at the PreRenderViewEvent (for JSF 2). This code is embedded in your facelet page:
<f:metadata>
<f:viewParam name="foo" value="#{bean.foo}"/>
<f:event type="preRenderView" listener="#{bean.doSomething}"/>
</f:metadata>
The f:event listener is executed before every page view.
When using h:commandlink(or commandbutton) inside a rich:dataTable, the action specified is never invoked, neither is the corresponding managed bean instantiated(whether it is at request or session scope)...
instead, the same request is performed.. (page reloads)..
have seen what appeared to be similar issue on forums, but is not actually the problem i am having..
the h:commandlink /button work ok outside of the rich:datatable..
Does anyone have any advice?
here is a code snippet:
<h:commandLink id="commLink" actionListener="#{hBean.test}" action="#{hBean.viewTranslation}">
<h:outputText value="#{trans.translationName}"/>
</h:commandLink>
</rich:column>
The bean is apparently request scoped and the datamodel is not been loaded during bean's construction (at least, during apply request values phase of the subsequent request). You need to preserve the same datamodel for the subsequent request, else JSF cannot locate the row item associated with the clicked link. The most straightforward way is to load the datamodel in the bean's constructor or #PostConstruct method.
A quick fix/test is to put bean in session scope. The datamodel will then be saved in the session scope and be available in the subsequent request. But this has more impact on user experience (e.g. unexpected results when having the same page opened in different browser windows/tabs in the same session). If you're already on JSF 2.0 (which is likely not the case since you're using RichFaces), then the new view scope would have been the solution.
Related questions:
h:commandLink is not been invoked - contains an overview of all possible causes of this behaviour.
If you are using RichFaces 3.0.0 through 3.3.3, use the tag a4j:keepAlive. It will works even with request scope.