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From José Antonio Pérez Testa <>
Subject Re: [Digester]How to access created objects
Date Tue, 04 Nov 2003 17:32:54 GMT
Hi Frank,
I'll try to explain as far as my knowdledge of Digester and my english 
skills could.
My article of reference is O'Reilly's one :

Frank Schaare wrote:

> Hi,
> i try to get familiar with the digester. Therefore i read all three 
> (not very much) articles mentioned on digester´s homesite and tried 
> some code like this:
> public void initSQLRules()
> {
>  try
>  {
>  Digester digester = new Digester();
>  digester.push(this);

Put 'this' on top of the stack.

>  digester.addObjectCreate("Abfragen",Abfragen.class);

When <Abfragen> is found create a new Abfragen object and put it on top 
of stack ( above 'this' )

>  digester.addObjectCreate("Abfragen/Abfrage",Abfrage.class);

When <Abfragen><Abfrage> is found create a new Abfrage object and put it 
on top of stack ( above the Abfragen instance )

>  digester.addBeanPropertySetter("Abfragen/Abfrage/Name","name");

When found the path "Abfragen/Abfrage/Name" call setter method 
'setName()' on current stack top object ( that is the Abfrage instance)
passing the value taken from the xml element Name converted to the 
argument type of the setName method.

>  digester.addBeanPropertySetter("Abfragen/Abfrage/SQL","wert");


>  digester.addSetNext("Abfragen/Abfrage","addAbfrage");

When </Abfrage> is found, remove current stack top object ( that is the 
Abfrage instance) and pass it as parameter to the addAbfrage() method of 
the actual
stack top object  ( the Abfragen instance )

>  digester.parse("my.xml"); 

Tell digester to parse the file my.xml.

>  }
>  catch (Exception e)
>  {
>  e.printStackTrace();
>  }
> }
> This seems to work, what exactly happen here ? Obviously, the digester 
> gets some rules an delegates xml parsing to a SAXParser.

Digester gets the rules that you are set in code

> How do i access (get) the generatet Bean ?

if  the Abfragen class has a method called
public void addAbfrage(Abfrage beanObject)
you will found your beans there.
Otherwise Digester will write a log saying that it couldn't find the method

> Where is the bean object createt ?

I think I've explained that above.

> Who has information about this mysterios stack ? 

If you enable tracing, you will get detailed information of what is 
going on during the parsing of the xml file.

> The Code 'digester.push(this);' seems to put the servlet instance on a 
> stack. What for ?

In order to keep track of the last object taken from the stack. You have 
to put another rule like

and add that method
     public void addAbfragen(Abfragen beanContainerObject)
to your servlet.
Digester will call it and pass the newly created Abfragen instance and 
you will have everything at your disposition.

> Are there any sites that gain a little more information as jakarta does ?
> thx for your answers.
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