MWDescriptorQueryParameterHandle.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.handles;

import org.eclipse.persistence.tools.workbench.mappingsmodel.MWModel;
import org.eclipse.persistence.tools.workbench.mappingsmodel.descriptor.relational.MWTableDescriptor;
import org.eclipse.persistence.tools.workbench.mappingsmodel.query.MWQuery;
import org.eclipse.persistence.tools.workbench.mappingsmodel.query.MWQueryParameter;
import org.eclipse.persistence.tools.workbench.utility.node.Node;

import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.mappings.OneToOneMapping;
import org.eclipse.persistence.oxm.XMLDescriptor;

/**
 * MWDescriptorQueryParameterHandle is used to isolate the painful bits of code
 * necessary to correctly handle references to MWQueryParameters.
 *
 * Since a MWQueryParameters is nested within a MWQuery which is nested
 * within the XML file for a MWClassDescriptor, we need to store a reference
 * to a particular parameter as a set of instance variables:
 *   - the name of the MWClassDescriptor
 *   - the signature of the containing query
 *   - the name of the query parameter
 *
 * This causes no end of pain when dealing with TopLink, property
 * change listeners, backward-compatibility, etc.
 */
public final class MWDescriptorQueryParameterHandle extends MWHandle {

    /**
     * This is the actual query parameter.
     * It is built from the class descriptor name, query signature,
     * and query parameter name, below.
     */
    private volatile MWQueryParameter queryParameter;

    /**
     * The class descriptor name, query signature, and query
     * parameter name are transient. They
     * are used only to hold their values until postProjectBuild()
     * is called and we can resolve the actual query parameter.
     * We do not keep these in synch with the query parameter itself because
     * we cannot know when the query parameter has been renamed etc.
     */
    private volatile String classDescriptorName;
    private volatile String querySignature;
    private volatile String queryParameterName;

    // ********** constructors **********

    /**
     * default constructor - for TopLink use only
     */
    private MWDescriptorQueryParameterHandle() {
        super();
    }

    public MWDescriptorQueryParameterHandle(MWModel parent, NodeReferenceScrubber scrubber) {
        super(parent, scrubber);
    }

    public MWDescriptorQueryParameterHandle(MWModel parent, MWQueryParameter queryParameter, NodeReferenceScrubber scrubber) {
        super(parent, scrubber);
        this.queryParameter = queryParameter;
    }


    // ********** instance methods **********

    public MWQueryParameter getQueryParameter() {
        return this.queryParameter;
    }

    public void setQueryParameter(MWQueryParameter queryParameter) {
        this.queryParameter = queryParameter;
    }

    protected Node node() {
        return getQueryParameter();
    }

    public MWDescriptorQueryParameterHandle setScrubber(NodeReferenceScrubber scrubber) {
        this.setScrubberInternal(scrubber);
        return this;
    }

    public void postProjectBuild() {
        super.postProjectBuild();
        if (this.classDescriptorName != null && this.querySignature != null && this.queryParameterName != null) {
            MWTableDescriptor classDescriptor = (MWTableDescriptor) this.getProject().descriptorNamed(this.classDescriptorName);
            if (classDescriptor != null) {
                MWQuery query = classDescriptor.getQueryManager().queryWithSignature(this.querySignature);
                if (query != null) {
                    this.queryParameter = query.getParameterNamed(this.queryParameterName);
                }
            }
        }
        // Ensure classDesriptorName, querySignature, and queryParameter name
        // are not used by setting them to null....
        // If the XML is corrupt and only some of these attributes is populated,
        // this will cause the populated attribute to be cleared out if the
        // objects are rewritten.
        this.classDescriptorName = null;
        this.querySignature = null;
        this.queryParameterName = null;
    }

    /**
     * Override to delegate comparison to the query parameter itself.
     * If the handles being compared are in a collection that is being sorted,
     * NEITHER query parameter should be null.
     */
    public int compareTo(Object o) {
        return this.queryParameter.compareTo(((MWDescriptorQueryParameterHandle) o).queryParameter);
    }

    public void toString(StringBuffer sb) {
        if (this.queryParameter == null) {
            sb.append("null");
        } else {
            this.queryParameter.toString(sb);
        }
    }


    // ********** TopLink methods **********

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

        descriptor.setJavaClass(MWDescriptorQueryParameterHandle.class);

        descriptor.addDirectMapping("classDescriptorName", "getClassDescriptorNameForTopLink", "setClassDescriptorNameForTopLink", "class-descriptor-name/text()");
        descriptor.addDirectMapping("querySignature", "getQuerySignatureForTopLink", "setQuerySignatureForTopLink", "query-signature/text()");
        descriptor.addDirectMapping("queryParameterName", "getQueryParameterNameForTopLink", "setQueryParameterNameForTopLink", "query-parameter-name/text()");

        return descriptor;
    }

    private String getClassDescriptorNameForTopLink() {
        return (this.queryParameter == null) ? null : this.queryParameter.getQuery().getOwningDescriptor().getName();
    }

    private void setClassDescriptorNameForTopLink(String classDescriptorName) {
        this.classDescriptorName = classDescriptorName;
    }

    private String getQuerySignatureForTopLink() {
        return (this.queryParameter == null) ? null : this.queryParameter.getQuery().signature();
    }

    private void setQuerySignatureForTopLink(String querySignature) {
        this.querySignature = querySignature;
    }

    private String getQueryParameterNameForTopLink() {
        return (this.queryParameter == null) ? null : this.queryParameter.getName();
    }

    private void setQueryParameterNameForTopLink(String queryParameterName) {
        this.queryParameterName = queryParameterName;
    }

}