EclipseLink/Examples/DBWS/DBWSIntermediateAttribute

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Naming Convention for schema elements

As seen in the Basic Table example, the DBWSBuilder-generated eclipselink-dbws-schema.xsd file derives <element-tag> names from the Database table metadata:

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns:xsd="http://www.w3.org/2001/XMLSchema"
 >
  <xsd:complexType name="empType">
    <xsd:sequence>
      <xsd:element name="empno" type="xsd:int" xsi:nil="false"/>
      <xsd:element name="ename" type="xsd:string" xsi:nil="true"/>
      <xsd:element name="job" type="xsd:string" xsi:nil="true"/>
      <xsd:element name="mgr" type="xsd:int" minOccurs="0" xsi:nil="true"/>
      <xsd:element name="hiredate" type="xsd:dateTime" xsi:nil="true"/>
      <xsd:element name="sal" type="xsd:decimal" xsi:nil="true"/>
      <xsd:element name="comm" type="xsd:int" minOccurs="0" xsi:nil="true"/>
      <xsd:element name="deptno" type="xsd:int" xsi:nil="true"/>
    </xsd:sequence>
  </xsd:complexType>
</xsd:schema>

Converting the database metadata into the names of <element-tag>'s is the job of o.e.p.tools.dbws.NamingConventionTransformer's

public interface NamingConventionTransformer {
 
    public enum ElementStyle {
        ELEMENT, ATTRIBUTE, NONE
    };
 
    public String generateSchemaName(String tableName);
 
    public String generateElementAlias(String originalElementName);
 
    public ElementStyle styleForElement(String originalElementName);
}

In the eclipselink-dbwsutils.jar, the built-in transformers form a Chain-of-Responsibility NCTChainOfResponsibility.png

In the o.e.p.tools.dbws.NamingConventionTransformer services file, the transformer chain is listed in order:

eclipselink-dbwsutils.jar
|  
+---META-INF
|   |   MANIFEST.MF
|   |  
|   \---services
|           org.eclipse.persistence.tools.dbws.NamingConventionTransformer
            contains 3 lines:
              org.eclipse.persistence.tools.dbws.ToLowerTransformer
              org.eclipse.persistence.tools.dbws.TypeSuffixTransformer
              org.eclipse.persistence.tools.dbws.SQLX2003Transformer

User-Provided NamingConventionTransformer

It is possible to change an <element-tag> to an "attribute" with a custom transformer. The user sub-classes o.e.p.tools.dbws.DefaultNamingConventionTransformer. For example, for the table

CREATE TABLE IF NOT EXISTS SIMPLE_TABLE (
  ID NUMERIC NOT NULL,
  NAME VARCHAR(25),	
  SINCE DATE, 
  PRIMARY KEY (ID) 
)

The following NamingConventionTransformer<code> will:

  • name the schema element 'simple'
  • make the element names lowercase
  • have the ID field represented as an attribute, and
  • skip the SINCE field
import org.eclipse.persistence.tools.dbws.DefaultNamingConventionTransformer;
import static org.eclipse.persistence.tools.dbws.NamingConventionTransformer.ElementStyle.ATTRIBUTE;
import static org.eclipse.persistence.tools.dbws.NamingConventionTransformer.ElementStyle.ELEMENT;
import static org.eclipse.persistence.tools.dbws.NamingConventionTransformer.ElementStyle.NONE;
 
public class MyNamingConventionTransformer extends DefaultNamingConventionTransformer {
 
    @Override
    public String generateSchemaAlias(String tableName) {
        return super.generateSchemaAlias("simple");
    }
 
    @Override
    public String generateElementAlias(String originalElementName) {
        return super.generateElementAlias(originalElementName.toLowerCase());
    }
 
    @Override
    public ElementStyle styleForElement(String elementName) {
        if ("id".equalsIgnoreCase(elementName)) {
            return ATTRIBUTE;
        }
        else if ("since".equalsIgnoreCase(elementName)) {
            return NONE;
        }
        return ELEMENT;
    }
}