MWDefaultNullValuePolicy.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 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 v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.mappingsmodel.mapping;

import java.util.List;

import org.eclipse.persistence.tools.workbench.mappingsmodel.MWModel;
import org.eclipse.persistence.tools.workbench.mappingsmodel.meta.MWTypeDeclaration;
import org.eclipse.persistence.tools.workbench.utility.node.Node;

import org.eclipse.persistence.exceptions.ConversionException;
import org.eclipse.persistence.internal.helper.ConversionManager;
import org.eclipse.persistence.mappings.foundation.AbstractDirectMapping;
import org.eclipse.persistence.oxm.XMLDescriptor;
import org.eclipse.persistence.oxm.mappings.XMLCompositeObjectMapping;
import org.eclipse.persistence.oxm.mappings.XMLDirectMapping;

public final class MWDefaultNullValuePolicy
    extends MWModel
    implements MWNullValuePolicy {

    private volatile String nullValue;

    private volatile MWTypeDeclaration nullValueType;



    // **************** Static methods **************

    public static XMLDescriptor buildDescriptor() {
        XMLDescriptor descriptor = new XMLDescriptor();

        descriptor.setJavaClass(MWDefaultNullValuePolicy.class);

        XMLCompositeObjectMapping nullValueTypeMapping = new XMLCompositeObjectMapping();
        nullValueTypeMapping.setAttributeName("nullValueType");
        nullValueTypeMapping.setReferenceClass(MWTypeDeclaration.class);
        nullValueTypeMapping.setXPath("null-value-type");
        descriptor.addMapping(nullValueTypeMapping);

        XMLDirectMapping nullValueMapping = (XMLDirectMapping) descriptor.addDirectMapping("nullValue", "null-value/text()");
        nullValueMapping.setNullValue("");

        return descriptor;
    }


    // ************* Constructors **************

    /** Default constructor - for TopLink use only */
    private MWDefaultNullValuePolicy() {
        super();
    }

    public MWDefaultNullValuePolicy(MWModel parent) {
        super(parent);
    }

    protected void initialize(Node parent) {
        super.initialize(parent);
        this.nullValueType = new MWTypeDeclaration(this, this.typeFor(java.lang.String.class));
        this.nullValue = "";
    }

    protected void addChildrenTo(List children) {
        super.addChildrenTo(children);
        children.add(this.nullValueType);
    }


    // *************** Accessors **************

    public boolean usesNullValue() {
        return true;
    }

    public String getNullValue() {
        return this.nullValue;
    }

    public void setNullValue(String newValue) {
        String oldValue = this.nullValue;
        this.nullValue = newValue;
        this.firePropertyChanged(NULL_VALUE_PROPERTY, oldValue, newValue);
    }

    public MWTypeDeclaration getNullValueType() {
        return this.nullValueType;
    }

    public void setNullValueType(MWTypeDeclaration newNullType) {
        if (newNullType == null) {
            throw new NullPointerException();
        }
        MWTypeDeclaration oldValue = getNullValueType();
        this.nullValueType = newNullType;
        this.firePropertyChanged(NULL_VALUE_TYPE_PROPERTY, oldValue, newNullType);
    }


    // **************** Runtime conversion ****************

    public void adjustRuntimeMapping(AbstractDirectMapping mapping) {
        mapping.setNullValue(this.nullValue());
    }

    protected /* private-protected */ Object nullValue() {
        if (this.nullValue == null || getNullValueType() == null)
            return null;

        Class nullClass = null;

        try {
            nullClass = Class.forName(getNullValueType().typeName());
        }
        catch (ClassNotFoundException cnfe) {
            // can't do anything with it, just don't do anything
            return null;
        }

        ConversionManager cm = ConversionManager.getDefaultManager();

        try {
            return cm.convertObject(this.nullValue, nullClass);
        }
        catch (ConversionException ce) {
         // can't do anything with it, just don't do anything
            return null;
        }
    }


    // **************** TopLink Only Methos ***************

    public MWNullValuePolicy getValueForTopLink() {
        return this;
    }

}