Le Dec 1, 2004, � 9:18 PM, Matt Raible a �crit :
On Dec 1, 2004, at 8:40 PM, David Geary wrote:
Le Dec 1, 2004, � 7:33 PM, Matt Raible a �crit :
Hello all,
I've been doing a bit of MyFaces development this week and enjoying it for the most part.
Glad to hear it Matt! 8-)
I have a couple questions about <h:outputLabel>:
1. Is there anyway to modify h:outputLabel to add an asterisk for required fields?
You can do that without modifying h:outputLabel, for example:
<h:loadBundle basename="messages" var="msgs"/> ... <h:outputLabel for="name" value="#{msgs.requiredNamePrompt}"/>
In your resource bundle:
requiredNamePrompt=*Name
Of course with that solution you're assuming the required state of the field in the view. That's probably better left to business logic, so you could do this instead:
<h:outputLabel for="name" value="#{backingBean.namePrompt}"/>
And BackingBean.getNamePrompt() would return the proper localized string, with an asterik if the property is required, and without an asterik otherwise.
Or, you could do this:
<h:panelGroup> <h:outputText value="*" rendered="#{backingBean.nameRequired}"/> <h:outputLabel value="#{msgs.namePrompt}"/> </h:panelGroup>
And have backingBean implement a boolean method named isNameRequired that returns the required status of the property in question. The h:outputText will only render if its rendered attribute is true.
Hmmm, sounds like I have to have a getter method for each form field on my managed bean? What a pain?
Isn't there a way to look up if the field is required and just add a * - a solution that's generic for all outputLabel's? I'm willing to hack source code or create components if I need to - I just need to know 2 things:
1. Yes/No - if I have to hack the source to make the dynamic lookup possible?
No hacking is required.
2. Where do I hack the source? I'm guessing there's some way to lookup the validation metadata for the inputs and use that data in the labels.
You could implementing a replacement for the Label renderer:
1. In a renderer method such as encodeBegin(), get the value of the renderer's component (encodeBegin is passed the component. Call the component's getValue method). In this case, the component is the label and the value is the id of the labeled component.
2. Get a reference to the labeled component. In a JSF component hierarchy, any component can find any other component in the hierarchy with the findComponent(String) method, where the String is the component's id. So the label can find the labeled component.
3. Find out if the labeled component is required. Input components implement the editableValueHolder interface, which defines an isRequired method.
4. Render according to whether the labeled component is required.
david
Thanks,
Matt
Do I have to subclass the existing JSP Tag to do this?
You hardly ever want to subclass an existing component tag, because tags are really just thin veneers for component/renderer pairs. You could, however, implement your own Label renderer and plug it into h:outputLabel. But I would opt for one of the easier solutions above.
2. Is it possible to auto-add a colon? I'm able to do this pretty easily with a custom taglib and Commons Validator, but it seems difficult with MyFaces? With Tapestry, I can subclass the existing component and add my own suffix (including a space before the colon for the French locale).
The same techniques for prepending an asterik will work for appending a colon. Again, you could implement your own Label renderer that does anything you want.
david
Thanks,
Matt
