Annotation Type XmlIDREF

@Retention(RUNTIME)
@Target({FIELD,METHOD})
public @interface XmlIDREF

Maps a JavaBean property to XML IDREF.

To preserve referential integrity of an object graph across XML serialization followed by a XML deserialization, requires an object reference to be marshaled by reference or containment appropriately. Annotations @XmlID and @XmlIDREF together allow a customized mapping of a JavaBean property's type by containment or reference.

Usage

The @XmlIDREF annotation can be used with the following program elements:

• a JavaBean property
• non static, non transient field

See "Package Specification" in javax.xml.bind.package javadoc for additional common information.

The usage is subject to the following constraints:

• If the type of the field or property is a collection type, then the collection item type must contain a property or field annotated with @XmlID.
• If the field or property is single valued, then the type of the property or field must contain a property or field annotated with @XmlID.

  Note: If the collection item type or the type of the property (for non collection type) is java.lang.Object, then the instance must contain a property/field annotated with @XmlID attribute.

• This annotation can be used with the following annotations: XmlElement, XmlAttribute, XmlList, and XmlElements.

Example: Map a JavaBean property to xs:IDREF (i.e. by reference rather than by containment)

  //EXAMPLE: Code fragment
  public class Shipping {
      @XmlIDREF public Customer getCustomer();
      public void setCustomer(Customer customer);
      ....
   }


  <!-- Example: XML Schema fragment -->
  <xs:complexType name="Shipping">
    <xs:complexContent>
      <xs:sequence>
        <xs:element name="customer" type="xs:IDREF"/>
        ....
      </xs:sequence>
    </xs:complexContent>
  </xs:complexType>

Example 2: The following is a complete example of containment versus reference.

   // By default, Customer maps to complex type xs:Customer
   public class Customer {
       
       // map JavaBean property type to xs:ID
       @XmlID public String getCustomerID();
       public void setCustomerID(String id);

       // .... other properties not shown 
   }


  // By default, Invoice maps to a complex type xs:Invoice
  public class Invoice {
   
      // map by reference
      @XmlIDREF public Customer getCustomer();       
      public void setCustomer(Customer customer);

     // .... other properties not shown here
  }

  // By default, Shipping maps to complex type xs:Shipping
  public class Shipping {

      // map by reference
      @XmlIDREF public Customer getCustomer();       
      public void setCustomer(Customer customer);
  }

  // at least one class must reference Customer by containment;
  // Customer instances won't be marshalled.
  @XmlElement(name="CustomerData")
  public class CustomerData {
      // map reference to Customer by containment by default.
      public Customer getCustomer();

      // maps reference to Shipping by containment by default. 
      public Shipping getShipping();     

      // maps reference to Invoice by containment by default. 
      public Invoice getInvoice();     
  }


  <!-- XML Schema mapping for above code frament -->

  <xs:complexType name="Invoice">
    <xs:complexContent>
      <xs:sequence>
        <xs:element name="customer" type="xs:IDREF"/>
        ....
      </xs:sequence>
    </xs:complexContent>
  </xs:complexType>

  <xs:complexType name="Shipping">
    <xs:complexContent>
      <xs:sequence>
        <xs:element name="customer" type="xs:IDREF"/>
        ....
      </xs:sequence>
    </xs:complexContent>
  </xs:complexType>

  <xs:complexType name="Customer">
    <xs:complexContent>
      <xs:sequence>
        ....
      </xs:sequence>
      <xs:attribute name="CustomerID" type="xs:ID"/>
    </xs:complexContent>
  </xs:complexType>

  <xs:complexType name="CustomerData">
    <xs:complexContent>
      <xs:sequence>
        <xs:element name="customer" type="xs:Customer"/>
        <xs:element name="shipping" type="xs:Shipping"/>
        <xs:element name="invoice"  type="xs:Invoice"/>
      </xs:sequence>
    </xs:complexContent>
  </xs:complexType>

  <xs:element name"customerData" type="xs:CustomerData"/>

  <!-- Instance document conforming to the above XML Schema -->
   <customerData>
      <customer customerID="Alice">
          ....
      </customer>

      <shipping customer="Alice">
          ....
      </shipping>
        
      <invoice customer="Alice">
          ....
      </invoice>
  </customerData>

Example 3: Mapping List to repeating element of type IDREF

    // Code fragment
    public class Shipping {
        @XmlIDREF
        @XmlElement(name="Alice")
            public List customers;
    }


    <!-- XML schema fragment -->
    <xs:complexType name="Shipping">
      <xs:sequence>
        <xs:choice minOccurs="0" maxOccurs="unbounded">
          <xs:element name="Alice" type="xs:IDREF"/>
        </xs:choice>
      </xs:sequence>
    </xs:complexType>

Example 4: Mapping a List to a list of elements of type IDREF.

    //Code fragment
    public class Shipping {
        @XmlIDREF
        @XmlElements(
            @XmlElement(name="Alice", type="Customer.class")
             @XmlElement(name="John", type="InternationalCustomer.class")
        public List customers;
    }


    <!-- XML Schema fragment -->
    <xs:complexType name="Shipping">
      <xs:sequence>
        <xs:choice minOccurs="0" maxOccurs="unbounded">
          <xs:element name="Alice" type="xs:IDREF"/>
          <xs:element name="John" type="xs:IDREF"/>
        </xs:choice>
      </xs:sequence>
    </xs:complexType>

Since:

1.6, JAXB 2.0

Author:

Sekhar Vajjhala, Sun Microsystems, Inc.

See Also:

• XmlID