foundation/org.eclipse.persistence.core/src/main/java/org/eclipse/persistence/oxm/annotations/XmlIsSetNullPolicy.java

/*
 * Copyright (c) 2011, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     Oracle = 2.2 - Initial contribution
package org.eclipse.persistence.oxm.annotations;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * <b>Purpose:</b> Provide a means of using annotations to customise the handling of null values
 * and their xml representation.
 * <p>This annotation provides the user with a mechanism to customise the way that EclipseLink
 * handles the reading and writing of null values. This version of NullPolicy makes use of an isSet method to differentiate
 * between values that were explicitly set to null vs values which are null due to being unset. In
 * this case the marshal behaviour specified by the nullRepresentationForXml will only be used if
 * the property was set. A set is only performed during unmarshal if an element was present in the
 * document. The following values can be specified:
 * <ul><li>xsiNilRepresentsNull - This indicates that during unmarshal, an element with an xsi:nil="true"
 * attribute specified should be unmarshaled as "null" into the object.</li>
 * <li>emptyNodeRepresentsNull - This indicates that during unmarshal, an empty node <code>"&lt;element/&gt;"</code>
 * should be unmarshalled to as null in the object model.</li>
 * <li>nullRepresentationForXml - Determines how a null value in the object model is written out
 * to XML.
 * <li>isSetMethodName - The name of the isSet method on the object owning this property. This
 * will be invoked to determine if a value of null was set or unset.  </li>
 * <li>isSetMethodParameters - A list of any parameter values and their types to be passed into
 * the isSet method when invoked at runtime. </li></ul>
 *
 * @see XmlNullPolicy
 * @see XmlMarshalNullRepresentation
 * @see XmlParameter
 */
@Target({ElementType.FIELD, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface XmlIsSetNullPolicy {
    boolean xsiNilRepresentsNull() default false;

    boolean emptyNodeRepresentsNull() default false;

    XmlMarshalNullRepresentation nullRepresentationForXml() default org.eclipse.persistence.oxm.annotations.XmlMarshalNullRepresentation.ABSENT_NODE;

    String isSetMethodName();

    XmlParameter[] isSetParameters() default {};
}