I have a composite component which is composed of other composite components. Now I would like to render only some of the child components within the parent component. From the Java EE tutorial I take it that I should probably bind my child components to some property of the backing bean for my parent component so that I can access their render attribute.
However, the NetBeans IDE does not know about a binding attribute for my composite components. So how am I supposed to do this?
Use case: The parent component is some wizard which should display only one of the child components at a time. Think of it as a poor man's tabbed view. I know there are libraries which provide ready-made components for this, but I do not want to add another dependency.
Netbeans is lying. That attribute is definitely supported on <ui:component>. Just use it and ignore the warning/error in the IDE. Or better, just use the rendered attribute; the need to conditionally render components is not a valid reason to prefer binding over rendered.
Related
I'm trying to add something to a composite component somebody else created and there is a #{cc.foo} in there. I can't seem to find where foo is defined, even doing a grep over the entire codebase.
What's the difference between cc.attrs.foo and cc.foo in general?
EDIT I found it in some jar, therefore I didn't see it in the search. Still the question generally remains. Thanks
What exactly is foo? Composite components (as other UIComponents) have certain properties predefined: for example, #{cc.rendered} or #{cc.clientId} are defined by the Java EE spec, not the user, so they are always available within composite components.
In general, #{cc.whatever} will be properties of the component itself: its component ID #{cc.id}, its client ID (i.e. what's rendered as the id attribute of the HTML tag) #{cc.clientID}, its parent component #{cc.parent}, etc. These are provided by Java EE. On the other hand, #{cc.attrs.whatever} are provided by the component developer: they will be the named attributes of the composite component: for each <composite:attribute name="myAttribute" ... /> in the <composite:interface> section of the composite component file, there will be a #{cc.attrs.myAttribute} available to use in the <composite:implmenentation> section of the composte component file.
Having gone through these excellent posts:
Why JSF saves the state of UI components on server?
Why does JSF save component tree state?
and midway the JavaEE6 tutorial I still have the following questions:
When I am developing a custom UI component whose values (styleClass, value, etc) are either defined statically(in the xhtml) or set via a bean, do I need to explicitly save/restore state in the extended component as well?
Is it correct to say that the scope of the UI components is view scoped?
How is the view identified behaviour? (If I navigate away from a view, the view gets rebuild the next time around. But if I open another tab, it is restored - at least the bean!)
When I am executing an Ajax call, I would expect that 'execute' part of the UI component would be restored&processed and the 'rendered' part would be restored&updated. After running into some problems with UI:repeat, it is not clear to which extend the component tree is to be restored and if is possible to partially edit.
As an example (I am not sure that it works like this): I define a UI:repeat that iterates over some values and creates some Ajax commandlinks. Whenever I call the command, it will restore the whole ui:repeat regardless of the Ajax scope (execute/render) that I have defined. So it will re-render the whole ui:repeat. Furthermore, I don't understand how it could ever -not- restore the ui:repeat as due to being a namingcontainer it will edit the id of my newly added component.
How can I define a build-time component (vs render-time) and why would I want to do this? (It seems that build time components are troublesome when mixed with rendertime, so why have both)
Thanks
When I am developing a custom UI component whose values (styleClass, value, etc) are either defined statically(in the xhtml) or set via a bean, do I need to explicitly save/restore state in the extended component as well?
Yes. You normally use StateHelper for this.
See also:
How to save state when extending UIComponentBase
JSF custom component: support for arguments of custom types, the attribute setter is never invoked
Adding Custom Attributes to Primefaces Autocomplete Component in JSF
Is it correct to say that the scope of the UI components is view scoped?
Absolutely not. UI component instances are request scoped. Only anything which is stored via StateHelper is in essence view scoped (and restored into newly created component instances during "restore view" phase).
See also:
JSF composite component - weird behavior when trying to save state
Backing bean in composite component is recreated on every request
How is the view identified behaviour? (If I navigate away from a view, the view gets rebuild the next time around. But if I open another tab, it is restored - at least the bean!)
It's likely requested from browser cache. Try submitting a form therein. The chance is big that you get a ViewExpiredException. You need to tell the browser to not cache dynamic pages. Putting a breakpoint on bean's constructor would also confirm that it's never been invoked.
See also:
Avoid back button on JSF web application
Is JSF 2.0 View Scope back-button safe?
javax.faces.application.ViewExpiredException: View could not be restored
When I am executing an Ajax call, I would expect that 'execute' part of the UI component would be restored&processed and the 'rendered' part would be restored&updated.
This is not true as to restore part. The "whole" view state is restored. Note that the view state does since JSF 2.0 not necessarily represent the entire component tree. You've found the explanation/answer to that already in the two links mentioned in your question.
How can I define a build-time component (vs render-time) and why would I want to do this? (It seems that build time components are troublesome when mixed with rendertime, so why have both)
This is called a "tag handler". I.e. just extend from TagHandler instead of UIComponent and implement according its contract. Tag handlers are useful if the sole goal is to build the view (the JSF component tree). They do not appear in the JSF component tree. As to when to create a custom component or a custom tag handler, check the "components" and "taghandlers" sections of OmniFaces showcase, it may give some new insights as to real world use cases of those things.
See also:
Custom Facelet component in JSF
JSTL in JSF2 Facelets... makes sense?
I am using JSF 1.2 and I want to create a custom component using ui:component tag. I need to use this component in many places in my application, so I want this component to be highly reusable.
The problem is that for each use of this custom component I need a backing bean to store my information and act as action listener for certain events. I use this component in about 15 places within my application, and I also use this component more than once within a single page.
I don't want to create a custom JSF component (with UIComponent, renderer etc) and I don't know how to manage the backing data.
Is there any way I can specify a class, and the custom component creates an instance of the class each time I use it?
Edit:
Is it possible to extend an existing JSF component? (I use Richfaces implementation)
Any help or idea are welcome.
I'm loving the jsf 2.0 composite component setup. One other thing I love is prependId="false" on forms. Is there an equivalent that can be defined in cc:interface or cc:implementation that will prevent jsf from creating a j_id to prepend to the ids defined within the composite component?
That's not possible. Just give the component a fixed id instead letting JSF autogenerate one. The same applies on forms by the way. This way you can still select them using CSS selectors.
Or better, just give them a styleClass so that you don't need to select by ID, for the case that this aversion was actually caused by inability to select components/elements by client ID (I don't see other feasible reasons).
I'm developing custom jsf2 component, that has an datasource attribute. There are some operations on datasource, that belongs to VIEW. For instance, there is a method that returns some image for column header, if the table is sorted by the column, and other image if it doesn't. In JSF1, each component has its Java class, extending UIComponent, so I can implement such methods there. However, I see that in JSF2, component class is created automatically from xhtml, so I doesn't know how to add methods to it. Can anybody explain me how to do it? s it possible to use both composite component and component class in one component?
In JSF 2 you can create component classes in Java in the same way you do in JSF 1 (the API may have changed a bit, but it is mostly the same. For example, look at http://weblogs.java.net/blog/driscoll/archive/2009/10/09/jsf-2-custom-java-components-and-ajax-behaviors