Re: [eclipselink-users] [MOXy] mapping inheritance of schema types

[amphoras <polly.c.chang@xxxxxxxxx>]

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
> 

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