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From Giota Karadimitriou <Giota.Karadimitr...@eurodyn.com>
Subject extend a node type
Date Tue, 13 Dec 2005 13:38:52 GMT
I am trying to extend the node type "nt:resource" in order to be able to add
custom properties to it.
I started by creating a new node type named my:myresource where 'my' is a
registered namespace. I also set the new node type to have a supertype of
"nt:resource".
However, I ran into the following problems:

1) Even though the new node type has "nt:resource" as a supertype as I mentioned
earlier, it does not automatically inherit any of its properties
(jcr:data,jcr:encoding,jcr:mimeType and jcr:lastModified). Maybe I am missing
sth but if the properties are not inherited, what is in fact inherited from a
certain supertype? As far as I can see properties are left out. So is it
children or is it sth else?

2)Since the properties were not inherited, I decided to find the properties of
nt:resource (PropDefs[]) and add them one by one to the new node type. I
therefore created a new PropDef array and I added all "nt:resource" properties
to it. I finally added an extra property "my:lang" to it. In the end, I assigned
this new PropDef array to the new node type. However, execution failed with
Exception 

org.apache.jackrabbit.core.nodetype.InvalidNodeTypeDefException:
[{http://www.my.com/my/1.0}myresource#{http://www.jcp.org/jcr/1.0}encoding]
invalid declaring node type specified

	at
org.apache.jackrabbit.core.nodetype.NodeTypeRegistry.validateNodeTypeDef
(NodeTypeRegistry.java:535)

	at
org.apache.jackrabbit.core.nodetype.NodeTypeRegistry.reregisterNodeType
(NodeTypeRegistry.java:1219)



This exception occured in validateNodeTypeDef method of NodeTypeRegistry class
in the sanity check part of the code where it checks the node type declaration
of the property


/**
             * sanity check:
             * make sure declaring node type matches name of node type definition
             */
            if (!name.equals(pd.getDeclaringNodeType())) {
                String msg = "[" + name + "#" + pd.getName()
                        + "] invalid declaring node type specified";
                log.debug(msg);
                throw new InvalidNodeTypeDefException(msg);
            } 

and the exception is thrown because 'name' = "my:resource" while
'pd.getDeclaringNodeType' = "nt:resource".
I think this is a bug because at this stage what should be checked is not
"equals" but also inheritance. What I mean is that maybe it should be also
checked whether 'pd.getDeclaringNodeType()' and 'name' have some other
connection besides equality, like inheritance for example; because
"my:myresource" is in fact nt:resource and in such a case, exception should not
be thrown

The way to implement what I just said would be to find the NodeTypeDef of 'name'
and the NodeTypeDef of 'pd.getDeclaringNodeType()' and check if the second is a
supertype of the first.

Of course maybe I am not heading towards the right direction here...but it is an
idea

3) Finally, to find a way arround the previous problem, I did the following:
Whenever I added an nt:resource property to the new node type; (e.g. when I
added jcr:data
to "my:myresource" propdef array) I also declared my:myresource as the declared
node type of the property using the following code (in order to avoid the
previous exception)

ws.getNamespaceRegistry().registerNamespace("my",
                "http://www.my.com/my/1.0");
QName mResourceName=new QName("http://www.my.com/my/1.0", "myresource");
((PropDefImpl)propDefsNew[i]).setDeclaringNodeType(mResourceName);

However this approach again failed with a new exception "Not implemented"

javax.jcr.RepositoryException: not yet implemented

	at
org.apache.jackrabbit.core.nodetype.NodeTypeRegistry.checkForConflictingContent
(NodeTypeRegistry.java:1615)

	at
org.apache.jackrabbit.core.nodetype.NodeTypeRegistry.reregisterNodeType
(NodeTypeRegistry.java:1256)



Could anybody give me some feedback on the above issues or have any ideas how to
work arround them to extend a nt:resource node type?


 



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