org.structr.web.datasource.XPathGraphDataSource.java Source code

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Here is the source code for org.structr.web.datasource.XPathGraphDataSource.java

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/**
 * Copyright (C) 2010-2016 Structr GmbH
 *
 * This file is part of Structr <http://structr.org>.
 *
 * Structr is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * Structr is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Structr.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.structr.web.datasource;

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathFactory;
import org.apache.commons.lang3.StringUtils;
import org.structr.common.error.FrameworkException;
import org.structr.core.GraphObject;
import org.structr.core.entity.AbstractNode;
import org.structr.web.common.GraphDataSource;
import org.structr.web.common.RenderContext;
import org.structr.web.entity.dom.DOMNode;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 *
 *
 */
public class XPathGraphDataSource implements GraphDataSource<List<GraphObject>> {

    private static final Logger logger = Logger.getLogger(XPathGraphDataSource.class.getName());

    @Override
    public List<GraphObject> getData(final RenderContext renderContext, final AbstractNode referenceNode)
            throws FrameworkException {

        final String xpathQuery = referenceNode.getProperty(DOMNode.xpathQuery);

        if (StringUtils.isBlank(xpathQuery)) {
            return null;
        }

        final Document document = ((DOMNode) referenceNode).getOwnerDocument();
        final XPathFactory factory = XPathFactory.newInstance();
        final XPath xpath = factory.newXPath();

        try {

            // FIXME: this code works only with absolute xpath queries because
            //        the xpath parser implementation is stupid (comparing object
            //        equality using ==).
            Object result = xpath.evaluate(xpathQuery, document, XPathConstants.NODESET);
            List<GraphObject> results = new LinkedList<>();

            if (result instanceof NodeList) {

                NodeList nodes = (NodeList) result;
                int len = nodes.getLength();

                for (int i = 0; i < len; i++) {

                    Node node = nodes.item(i);

                    if (node instanceof GraphObject) {

                        results.add((GraphObject) node);
                    }
                }

            } else if (result instanceof GraphObject) {

                results.add((GraphObject) result);
            }

            return results;

        } catch (Throwable t) {

            t.printStackTrace();

            logger.log(Level.WARNING, "Unable to execute xpath query: {0}", t.getMessage());
        }

        return Collections.EMPTY_LIST;

    }
}