core/org.eclipse.smila.processing.pipelets.xmlprocessing/code/src/org/eclipse/smila/processing/pipelets/xmlprocessing/XPathExtractorPipelet.java

/***********************************************************************************************************************
 * Copyright (c) 2008, 2011 Attensity Europe GmbH and brox IT Solutions GmbH. All rights reserved. This program and the
 * accompanying materials are made available under the terms of the Eclipse Public License v1.0 which accompanies this
 * distribution, and is available at http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors: Daniel Stucky (empolis GmbH) - initial API and implementation
 *               Andreas Weber (Attensity Europe GmbH) - data model simplification
 **********************************************************************************************************************/

package org.eclipse.smila.processing.pipelets.xmlprocessing;

import org.eclipse.smila.blackboard.Blackboard;
import org.eclipse.smila.datamodel.Value;
import org.eclipse.smila.processing.ProcessingException;
import org.eclipse.smila.processing.parameters.ParameterAccessor;
import org.eclipse.smila.processing.pipelets.xmlprocessing.util.XPathUtils;
import org.eclipse.smila.utils.xml.XMLUtils;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

/**
 * Pipelet that extracts elements selected by XPath and converts them in appropriate data types (Boolean, Double,
 * String). The possible properties are:
 * <ul>
 * <li>xpath: the XPath</li>
 * <li>seperator: the seperator (optional)</li>
 * <li>namespace: the namespace (optional)</li>
 * <li>inputName: name of the Attribute/Attachment to read the XML Document from</li>
 * <li>outputName: name of the Attribute/Attachment to store the extracted value in</li>
 * <li>inputType: the type (Attribute or Attachment of the inputName</li>
 * <li>outputType: the type (Attribute or Attachment of the outputtName</li>
 * </ul>
 */
public class XPathExtractorPipelet extends AXmlTransformationPipelet {
  /**
   * The name of the XSLT file used for the transformation.
   */
  public static final String PROP_XPATH = "xpath";

  /**
   * The separator property.
   */
  public static final String PROP_SEPARATOR = "separator";

  /**
   * The namespace property.
   */
  public static final String PROP_NAMESPACE = "namespace";

  @Override
  protected void processRecord(final Blackboard blackboard, final ParameterAccessor paramAccessor, final String id)
    throws Exception {

    final String xpath = paramAccessor.getRequiredParameter(PROP_XPATH);
    final String separator = paramAccessor.getParameter(PROP_SEPARATOR, "");
    final String namespace = paramAccessor.getParameter(PROP_NAMESPACE, "");
    final Element namespaceElement = createNamespaceElement(namespace);
    final Document inputDocument = createDocument(blackboard, id, paramAccessor);
    if (inputDocument != null) {
      final Object result = XPathUtils.queryForIndexField(inputDocument, xpath, namespaceElement, separator);
      if (result != null) {
        if (isStoreInAttribute(getOutputType(paramAccessor))) {
          Value value = null;
          if (result instanceof Boolean) {
            value = blackboard.getDataFactory().createBooleanValue((Boolean) result);
          } else if (result instanceof Double) {
            value = blackboard.getDataFactory().createDoubleValue((Double) result);
          } else {
            value = blackboard.getDataFactory().createStringValue(result.toString());
          }
          blackboard.getMetadata(id).put(getOutputName(paramAccessor), value);
        } else {
          storeResult(blackboard, id, result.toString(), paramAccessor);
        }
      }
    }
  }

  /**
   * @return namespace Element created from namespace string.
   */
  private Element createNamespaceElement(final String namespace) throws ProcessingException {
    final Document doc = XMLUtils.getDocument();
    final Element namespaceElement = doc.createElement("NamespaceDef");
    final String[] namespaces = namespace.split(" ");
    for (int i = 0; i < namespaces.length; i++) {
      if (!"".equals(namespaces[i].trim())) {
        final String[] nsItems = namespaces[i].split("=");
        if (nsItems.length != 2) {
          throw new ProcessingException("Property " + PROP_NAMESPACE
            + " in invalid format [Namespace;ns1=val ns2=val]");
        }
        namespaceElement.setAttribute("xmlns:" + nsItems[0], nsItems[1]);
      }
    }
    return namespaceElement;
  }
}