Castor code generator has problems with xml schema groups

accept bug

I am also using the IMS Content Packaging schema and experiencing the same
problem outlined above. I would like to use Castor and would have some time to
look into fixing this issue.

I am new to Castor and unfamiliar with the code and I was wondering if Arnaud
could give me some pointers as to where I should start and what might be going
wrong?

Thank you very much for your help and for Castor in general! It is a great
piece of work.

Is Jack's suggestion of modifying org.exolab.castor.xml.schema.Group to set it's
'minOccurs' attribute to 0 the correct fix?

Thanks!

The proposed fix is incorrect, you cannot set the value to 0 it is only a
workaround.
The main problem comes from the XML Schema design:
<xsd:group name="grp.any">
<xsd:sequence>
<xsd:any namespace="##other" processContents="strict" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:group>
is a group that can be empty
<xsd:complexType name="metadataType">
<xsd:sequence>
<xsd:group ref="grp.any"/> XXXXXXX
</xsd:sequence>
</xsd:complexType>

XXXX refers to a group that must appear once (minOccurs=1 by default) but it
can be empty by the definition of the group.

This is very bad designed since it is equivalent in OO performance-term that an
Object will hold a reference to an object that can be empty but not null.
I would advise as a workaround to refer to the group as:
<xsd:group ref="grp.any" minOccurs="0"/>

However Castor shouldn't throw an exception when reading valid document but I
am still unclear about what we should do:

1- detect that the group is required
2- detect that the group itself can be empty
3- instantiate a EMPTY vector of AnyNode
...not sure if it is a good solution

Created an attachment (id=233)
Grp_any.java generated for <xsd:group name="grp.any">

Created an attachment (id=234)
Grp_anyDescriptor.java generated for <xsd:group name="grp.any">

Arnaud,

Thank you very much for your response.

I think the solution that would match the schema most closely to my mind would
be that an instance of Grp_any is created at unmarshalling and that
Grp_any.getAnyObjectCount() returns 0. For example:

Manifest manifest = Manifest.unmarshal(someReader);
Metadata metadata = manifest.getMetadata();
Grp_any a = metadata.getGrp_any();

for the following XML:

<manifest>
<metadata>
</metadata>
</manifest>

a.getAnyObjectCount() would return 0.

I would be happy to have a go at implementing this is you think it is the
correct approach and if you could maybe give me a pointer to how this might be done.

Regards,
Simon.

Created an attachment (id=235)
Descriptor generated for metadataType that references a grp.any group

Is a possible solution to modify the source code generator so that:

In the case that a class contains a group with a minOccurs of 1 and that group
itself can be empty
then
the containing class creates an instance of the class representing the group in
its constructor?

For example rather than:

public ManifestType()

could we generate:

public ManifestType()

and if so is this a good solution?

I started looking into this. It looks like the "_manifestList = new Vector();"
line is added by
org.exolab.castor.builder.CollectionInfo.generateInitializerCode which is called
by org.exolab.castor.builder.SourceFactory.handleField

Is it feasible to modify the source generator so that SourceFactory.handleField
adds a line to the constructor that creates a instance of a group as for
_manifestList above when it is called on a group with minOccurs=1 that can be empty?

Thanks a lot.

Created an attachment (id=245)
ManifestType.java that contains a Grp_any