org.eclipse.persistence.internal.jpa.jpql.JPQLFunctionsAbstractBuilder Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of eclipselink Show documentation
EclipseLink build based upon Git transaction 346465e
There is a newer version: 5.0.0-B05
/*
 * Copyright (c) 2024 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 - initial API and implementation
//
package org.eclipse.persistence.internal.jpa.jpql;

import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.descriptors.VersionLockingPolicy;
import org.eclipse.persistence.internal.helper.DatabaseField;
import org.eclipse.persistence.jpa.jpql.parser.EclipseLinkAnonymousExpressionVisitor;
import org.eclipse.persistence.jpa.jpql.parser.IdExpression;
import org.eclipse.persistence.jpa.jpql.parser.IdentificationVariable;
import org.eclipse.persistence.jpa.jpql.parser.StateFieldPathExpression;
import org.eclipse.persistence.jpa.jpql.parser.VersionExpression;
import org.eclipse.persistence.mappings.DatabaseMapping;

import java.util.List;

/**
 * JPQL exclusive ID(), VERSION() functions/expressions are transformed there to StateFieldPathExpression.
 * It should be used in the future for another JPQL functions/expressions which are not available at the DB level.
 * E.g. For Entity e with idAttr as a primary key: SELECT ID(e) FROM Entity e -> SELECT e.idAttr FROM Entity e
 * For Entity e with versionAttr as a version attribute: SELECT VERSION(e) FROM Entity e -> SELECT e.versionAttr FROM Entity e
 *
 * @author Radek Felcman
 * @since 5.0
 */
public abstract class JPQLFunctionsAbstractBuilder extends EclipseLinkAnonymousExpressionVisitor {

    /**
     * The {@link JPQLQueryContext} is used to query information about the application metadata and
     * cached information.
     */
    final JPQLQueryContext queryContext;

    protected JPQLFunctionsAbstractBuilder(JPQLQueryContext queryContext) {
        this.queryContext = queryContext;
    }

    /**
     * For Entity e with idAttr as a primary key: SELECT ID(e) FROM Entity e -> SELECT e.idAttr FROM Entity e
     *
     * @param expression The {@link IdExpression} to visit
     */
    @Override
    public void visit(IdExpression expression) {
        //Fetch identification variable info
        IdentificationVariable identificationVariable = (IdentificationVariable) expression.getExpression();
        String variableText = identificationVariable.getText();
        String variableName = identificationVariable.getVariableName();

        //Get id attribute name
        ClassDescriptor descriptor = this.queryContext.getDeclaration(variableName).getDescriptor();
        List primaryKeyFields = descriptor.getPrimaryKeyFields();
        String idAttributeName = getIdAttributeNameByField(descriptor.getMappings(), primaryKeyFields.get(0));
        StateFieldPathExpression stateFieldPathExpression = new StateFieldPathExpression(expression.getParent(), variableText + "." + idAttributeName);
        expression.setStateFieldPathExpression(stateFieldPathExpression);

        //Continue with created StateFieldPathExpression
        //It handle by ObjectBuilder booth @Id/primary key types (simple/composite)
        expression.getStateFieldPathExpression().accept(this);
    }

    /**
     * For Entity e with versionAttr as a version attribute: SELECT VERSION(e) FROM Entity e -> SELECT e.versionAttr FROM Entity e
     *
     * @param expression The {@link VersionExpression} to visit
     */
    @Override
    public void visit(VersionExpression expression) {
        //Fetch identification variable info
        IdentificationVariable identificationVariable = (IdentificationVariable) expression.getExpression();
        String variableText = identificationVariable.getText();
        String variableName = identificationVariable.getVariableName();

        //Get version attribute name
        ClassDescriptor descriptor = this.queryContext.getDeclaration(variableName).getDescriptor();
        String versionAttributeName = ((VersionLockingPolicy) descriptor.getOptimisticLockingPolicy()).getVersionMapping().getAttributeName();
        StateFieldPathExpression stateFieldPathExpression = new StateFieldPathExpression(expression.getParent(), variableText + "." + versionAttributeName);
        expression.setStateFieldPathExpression(stateFieldPathExpression);

        //Continue with created StateFieldPathExpression
        expression.getStateFieldPathExpression().accept(this);
    }

    private String getIdAttributeNameByField(List databaseMappings, DatabaseField field) {
        for (DatabaseMapping mapping : databaseMappings) {
            if (field.equals(mapping.getField()) || mapping.isPrimaryKeyMapping()) {
                return mapping.getAttributeName();
            }
        }
        return null;
    }
}