Uh, nevermind, it does work. The key is to make sure every element in the inheritance hierarchy is set up correctly to refer all the way back up to Root. I checked this several times, but there are several "leaf" types and I missed one. :P Then use the "xml schema 'type' attribute" in Root, and make sure the indicator dictionary has an entry for each type in the hierarchy. Then this works fine. :)
Thanks,
Polly
amphoras wrote:
Hi,
My schema defines the following inheritance:
<xsd:complexType name="RootType" abstract="true">
<xsd:sequence>
<xsd:element ref="field1" minOccurs="0"/>
</xsd:sequence>
</xsd:complexType>
<xsd:complexType name="BranchType" abstract="true">
<xsd:complexContent>
<xsd:extension base="RootType">
<xsd:sequence>
<xsd:element ref="field2" maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:complexType name="LeafType">
<xsd:complexContent>
<xsd:extension base="BranchType">
<xsd:element ref="field3" maxOccurs="unbounded"/>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
The Java classes also mirror this inheritance tree:
public class Root {
private String field1;
}
public class Branch extends Root {
private String field2;
}
public class Leaf extends Branch {
private String field3;
}
Actually, Root and Branch ought to be abstract classes, but EclipseLink threw instantiation exceptions complaining about missing no-arg constructor until I took out the "abstract".
I expect to parse XML that looks like this into the Leaf object:
<Leaf>
<field1>...</field1>
<field2>...</field2>
<field3>...</field3>
</Leaf>
I don't want to redundantly map the fields from Branch and Root in Leaf, so I am trying to map each of those classes to its corresponding type in the schema. In the Workbench, I have these settings:
1. Leaf has a mapping for field3, the class is marked as a child descriptor, and its parent is Branch.
2. Branch has a mapping for field2, the class is marked as a child descriptor, and its parent is Root.
3. Root has a mapping for field1, the class is marked as a parent, and then... I'm stuck.
The problem is:
* I cannot use the Class Extraction Method, because it looks like this hook is never called for XML projects.
* I cannot use the Class Indicator Field's "xml schema type attribute", because I assume this means that I need an an attribute like "xsi:type='Leaf'", and my schema does not allow this attribute.
* I cannot use the Class Indicator Field's "specify field" setting because there's no element inside the <Leaf></Leaf> tags that will tell me what class to use.
So I am perplexed. How come EclipseLink can't tell that it should use the Leaf class if the xml element name is "Leaf"? I have already set the "Schema Context" to "Leaf". Why does EclipseLink need something else to tell it what type to use?
Is there a better way to specify inheritance in XML mappings without having to use the Map Inherited Attributes -> To Root Minus One option? That would force me to remap the same attributes over and over again and be a pain if the root definition ever changes.
Thanks for your help,
Polly
