Hi,
to make a generic component thyt for example edits hibernate entities
and to communicate the Entity to edit
declare it like this:
public class EntEdit<T>{
...
@Retain private Class _persistentClass;
public void pageLoaded() throws Exception{
//this only works when component is embeded
//@Component MyGenComp<Document> documentEditor;
//and component id must match field name, or field name
prefixed with "_"
String containerClassName =
_resources.getContainer().getComponentResources().getComponentModel().getComponentClassName();
//First we need Class name of the container that embeds us
Class cl = Class.forName(containerClassName);
Field field = null;
try {
//try if id is same as field name
field = cl.getDeclaredField(_resources.getId());
} catch (NoSuchFieldException e) {}
try {
//try if id is same as field name prefixed with "_"
if(field == null) field =
cl.getDeclaredField("_"+_resources.getId());
} catch (NoSuchFieldException e) {}
if(field != null){
//now we can use reflection to extract generic info
Object fieldType = field.getGenericType();
if(fieldType instanceof ParameterizedType){
//if it is really parametrized
ParameterizedType parameterizedType =
(ParameterizedType) fieldType;
Type type = parameterizedType.getActualTypeArguments()[0];
//if you declare more than one parameterized type ..
class MyGenComp<T,E>...
//use parameterizedType.getActualTypeArguments()[0,1,2...]
//if it is not complex geneirc def we can cast it to Class
if(type instanceof Class){
//now we know what <T> realy is
_persistentClass = (Class)type;
}
}//else we could throw a nice error to notify developer of
the requirement
}//else throw exception saying that component needs to be
embeded using @Component annotation
}
}
then in your page you could:
<t:delegate to="editor">
<t:block><div t:id="documentEditor"></div></t:block>
<t:block><div t:id="addressEditor"></div></t:block>
...
you can not avoid declaring these things somewhere,
so creating subclasses maybe is not so much worse
in your page class add:
@Component EntEdit<Document> documentEditor;
@Component EntEdit<Address> addressEditor;
On Wed, Mar 5, 2008 at 11:31 PM, Angelo Chen <[EMAIL PROTECTED]> wrote:
>
> Hi Davor,
>
> yes, I like to try that out, thanks.
>
>
> A.C.
>
>
> Davor Hrg wrote:
> >
>
>
> > I've struggled with many internal classes to see how generic
> > components could be achieved,
> > but after failing to find simple way to pass generic declaration to
> > component.
> >
> > I found a way to do it from inside the component,
> > but it works only for components, not for pages...
> >
> > I'm still looking is there a real bebefit from this...
> >
> > If this is helpful for you,
> > I can give you the snippet ...
> >
> > Davor Hrg
> >
> >
> > On Wed, Feb 27, 2008 at 1:48 PM, Angelo Chen <[EMAIL PROTECTED]>
> > wrote:
> >>
> >> Hi Howard,
> >>
> >> This is a very nice feature, in my app, I have many small tables, say
> >> 30, so
> >> to edit those 30 objects I have to create 30 page classes without
> >> template,
> >> that's a big saving. I'd like to save further, is there a way that we
> >> can
> >> create a generic page class that can be called from other pages? if this
> >> is
> >> possible then we save another 30 page classes. if this is not possbile I
> >> am
> >> thinking of 'embedding' the edit class in a main page class, say:
> >>
> >> // main page class for applicants
> >>
> >> public class AdminApplicant {
> >>
> >> // nested page class for the AdminApplicant.tml to call edit
> >> objects
> >>
> >> public class Edit extends EditPage<Applicant> {
> >> };
> >> }
> >>
> >> but the "embedded" Edit class is not visible in the AdminApplicant.tml,
> >> is
> >> there a way to make this works?
> >>
> >> Thanks,,
> >>
> >> A.C.
> >>
> >>
> >>
> >>
> >> Howard Lewis Ship wrote:
> >> >
> >> > To be more specified,
> >> >
> >> > you can define a base class:
> >> >
> >> > package com.myapp.base;
> >> >
> >> > public class EditPage<T> {
> >> >
> >> > @Persist private T _object;
> >> >
> >> > public T getObject() { return _object; }
> >> >
> >> > public void setObject(T object) { _object = object; }
> >> >
> >> > . . .
> >> > }
> >> >
> >> > So you can create a page that can edit an arbitrary object. EditPage
> >> > will have its own Tapestry template containing, say, a BeanEditForm.
> >> >
> >> > Now, you can define a new class:
> >> >
> >> > package com.myapp.pages;
> >> >
> >> > public class EditAccount extends EditPage<Account>
> >> > {
> >> > }
> >> >
> >> > EditAccount will inherit logic and template from EditPage.
> >> >
> >> > Further, the getObject() and setObject() properties will be bound to
> >> > the type Account. This takes some doing, as the type of property
> >> > object of class EditPage is nominally java.lang.Object (due to type
> >> > erasure). However, Tapestry does a bit of work with reflection to
> >> > deduce the effective type of the property (Account).
> >> >
> >> > This is a very, very high level of reuse ... and once again, we are
> >> > leveraging Java's type system to help us, rather than traditional Java
> >> > coding where we spend our time "appeasing" the type system.
> >> >
> >> >
> >> >
> >>
> >> --
> >> View this message in context:
> >> http://www.nabble.com/T5%3A-5.0.10-new-features-tp15528824p15712557.html
> >>
> >>
> >> Sent from the Tapestry - User mailing list archive at Nabble.com.
> >>
> >>
> >> ---------------------------------------------------------------------
> >> To unsubscribe, e-mail: [EMAIL PROTECTED]
> >> For additional commands, e-mail: [EMAIL PROTECTED]
> >>
> >>
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: [EMAIL PROTECTED]
> > For additional commands, e-mail: [EMAIL PROTECTED]
> >
> >
> >
>
> --
> View this message in context:
> http://www.nabble.com/T5%3A-5.0.10-new-features-tp15528824p15862092.html
>
>
> Sent from the Tapestry - User mailing list archive at Nabble.com.
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: [EMAIL PROTECTED]
> For additional commands, e-mail: [EMAIL PROTECTED]
>
>
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
