Yep,
allready tried that.... errors on the fact the the specific object doesn't have the requested property.... maybe I'll need to add an additional domain object have ALL the methods and convert the underlying objects on the backingbean...
Peter,
The APIs you are looking at to introspect properties in a class are the same ones that a JSF implementation uses as it is processing value binding expressions ... the bean introspection APIs that are built in to the JDK. The APIs are all documented in the JavaBeans specification (for more information start at <http://java.sun.com/products/javabeans/>), but it goes something like this:
BeanInfo beanInfo = Introspector.getBeanInfo(Customer.class);
PropertyDescriptor props[] = beanInfo.getPropertyDescriptors();
This gives you an array of descriptors for all the JavaBean properties defined in this class, including Method objects pointing at the getter and setter methods so you can use reflection APIs to call them dynamically.
If this is all a bit low level for your taste, you can also explore the APIs in Commons BeanUtils (http://jakarta.apache.org/commons/beanutils), which is a dependency of both the MyFaces and RI JSF implementations (so you'll have it available in your apps already).
Craig
On 11/24/05, Marius Kreis <[EMAIL PROTECTED]> wrote:Good point. You could use
<h:outputText value="#{user.address}" rendered="#{ user.class.name eq
"Customer"}">
But I doubt that it works... I think the _expression_ wil be evaluated
first and then throw an exception... sorry.
Peter Maas wrote:
> I understand that this is possible, but how can I test this within a
> tableGrid component without jstl?
>
> On 11/24/05, *Marius Kreis* < [EMAIL PROTECTED]
> <mailto:[EMAIL PROTECTED]>> wrote:
>
> Hi Peter.
> Perhaps you can check for the class of the object with
> user.class.name <http://user.class.name>
> I think this should query user.getClass().getName() .... and then you
> can compare it to "User" or "Customer"....
>
> Peter Maas wrote:
> > Hi all,
> >
> > I'm probably missing something obvious, but how can I 'detect' the
> > existence of a property on a bean? I have a managed bean return a
> list
> > of users, which might can be a plain user or an extended 'customer'
> >
> > class User{
> > String firstname;
> > String lastname;
> > String email;
> >
> > // getters and setters
> > }
> >
> > class Customer extends User{
> > String address;
> > // etc.
> > }
> >
> >
> > Now if I want to mix those objects in one single dataTable I
> cannot find
> > a way to display properties from
> > customer objects.... the code will break on plain user objects, and
> > complains about missing properties.
> >
> > I tried using jstl inside the table, but I'm not sure how the 'test'
> > properties of iterated items in the dataTable... a simple ${!empty
> > user.address } doesn't work.
> >
> > Actually, I would prefer to NOT use jstl..... but stick to
> JSF.... is it
> > possible with the existing tags?
> >
> > regards,
> >
> > Peter
>
>
