With XDoclet, Middlegen, java2hbm, hbm2java, wsdl2java, and all the other code generators out there, I've become a lazy programmer. I was wondering if anyone has been able to map a generated JAXB binding or if it were even possible?

JAXB bindings work through interfaces and implementations (e.i., objectType as the interface with objectTypeImpl as the implementing class) which I think can be handled through <sub-class> and <discriminator> entries into the hbm (maybe?). However, JAXB doesn't like to add setters for their collection elements prefering that you use the getter and then add/remove/update each element to the collection returned. This seems like a problem because a JAXB binding doesn't adhere to the JavaBean pattern here. So, is the prospect of mapping a JAXB binding far-fetched here?

Thanks,
Nathan

If you like those tools, you could always help out.

It seems like it should not be too hard to create either a velocity template or an XSLT template you could run with ant to automatically generate your JAXB bindings.

You can extend middlegen with your own velocity templates using a file producer to gen mappings based on your database tables. Though I'm not sure why you would want to.

Hi all!

Is there any possibility in the upcomming releases to use the jaxb generated interfaces with Hibernate? I'm just a beginner, but it looks for me, that having a possibility to specify a factory for Hibernate to instancianate the classes would be one step in this direction...

Any suggestions?

Hi all, my first post on these forums.

One month ago, if you'd asked what I knew about Hibernate, I'd have gone off about something animals do in the winter, but today, after a rather intense first two weeks, and some interesting discoveries, I now have a system in place, that goes:

DTD -> (XSL) -> "pure XML" -> XSD -> Hibernate -> MS-SQL

and do the complete reverse to the original format.

I do agree, that the whoel getter/setter issue is a problem with JAXB and Hibernate. Not only that, but our dear users (don't we all love them?) decided that they would send in their DTD fields in any order. This meant that I had to create 1-1-M bridging objects (tables) to allow for me to use the <xsd:all> tags.

The problem with the creation of the getter/setter for the parent objects - for the hibernate mapping properties, was solved by a colleague, who apparently loves do machine code. He solved this problem by modifying the ant-build build.xml like this:

-------------------------------------------------------------------------------------

<target name="codegen" description="Generate JAXB classes" >
<!-- generate the Java content classes from the schema -->
<echo message="Compiling the schema..."/>
<property name="build.src" value="." />

<xjc schema="input.xsd" target="${build.src}" package="my.package"/>

<replace dir="${build.src}" token="protected java.util.List"
value="protected java.util.List" />

<replaceregexp match="java\.util\.List get(.+)\(\);"
replace="java.util.List /\*NOP\*/ get\1\(\);
void set\1\(java.util.List _\1\);" byline="true" >
<fileset dir="${build.src}" />
</replaceregexp>
<replaceregexp match="new java\.util\.List()"
replace="new java\.util\.ArrayList" byline="true" >
<fileset dir="${build.src}" />
</replaceregexp>
<replaceregexp match="public java.util.List get(.+)\(\).*\{"
replace="public void set\1\(java.util.List _\1\) \{
this._\1 =new com.sun.xml.bind.util.ListImpl( _\1);
\}
public java.util.List /\*NOP\*/get\1\(\) \{" byline="true" >
<fileset dir="${build.src}" />
</replaceregexp>


<!-- generate the javadocs from the content classes -->
<mkdir dir="docs/api"/>
<javadoc packagenames="my.package"
sourcepath="."
destdir="docs/api"
windowtitle="Generated Interfaces for input.xsd">
<classpath refid="classpath" />
</javadoc>
</target>
------------------------------------------------------------------------------------

If you can read that, basically, he tells it to traverse the package looking for anywhere that the JAXB generates a java.util.List GET (1-to-Many) and replaces that with with both a GET and SET...that's if I understand it correctly. :)

To aid in my JAXB to Hibernate, I create a 0-1 element in each child Complex-Type...like this:

------------------------------------------------------------------------------------
<xsd:complexType name="Grandparent">
<xsd:sequence>
<xsd:element name="Name" type="xsd:string" minOccurs="1">
<xsd:element name="Parent" type="Parent" minOccurs="0" maxOccurs="unbounded"/>
</xsd:sequence>
<xsd:attribute name="HumanID" type="xsd:long"/>
</xsd:complexType>

<xsd:complexType name="Parent">
<xsd:sequence>
<xsd:element name="Name" type="xsd:string" minOccurs="1">
<xsd:element name="Grandparent" type="Grandparent" minOccurs="0"/>
<xsd:element name="Children" type="Children" minOccurs="0" maxOccurs="unbounded"/>
</xsd:sequence>
<xsd:attribute name="HumanID" type="xsd:long"/>
</xsd:complexType>
------------------------------------------------------------------------------------
If I recall properly, JAXB will create a getter for the Grandparent in Parent, and that little build.xml change will create a setter for it.

The reason I do this, is because Java works in a "Parent-has-children" way, while relational databases work in a "child-has-Parent" way...exactly inverse. By creating the link to the Grandparent element in my XSD, I create what I think as a trully neutral object design. From there you can map to XML or to databases. Of course, there is one caveat with this, and PLEASE don't forget this. When you marshall your code against this type of XSD, PLEASE PLEASE PLEASE PLEASE PLEASE, go through your tree and set the "Grandparent" type elements to null, otherwise you will get an infinite loop...

I hope this provides a little assistance. I'll start checking the forums more now that I've got my system running very smoothly (with great effort and great thanks to Hibernate). And I'd also love to hear if someone found another way to do it.

-G

PS. My thanks Mikey N. for his "hack".