restconf/restconf-nb/src/main/java/org/opendaylight/restconf/nb/rfc8040/streams/XMLDataTreeCandidateFormatter.java

   1 /*
   2  * Copyright (c) 2020 PANTHEON.tech, s.r.o. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.restconf.nb.rfc8040.streams;
   9
  10 import java.io.IOException;
  11 import java.io.StringWriter;
  12 import java.time.Instant;
  13 import java.util.List;
  14 import javax.xml.XMLConstants;
  15 import javax.xml.stream.XMLStreamException;
  16 import javax.xml.xpath.XPathExpressionException;
  17 import org.opendaylight.yangtools.yang.data.tree.api.DataTreeCandidate;
  18 import org.opendaylight.yangtools.yang.model.api.EffectiveModelContext;
  19
  20 public final class XMLDataTreeCandidateFormatter extends DataTreeCandidateFormatter {
  21     private static final XMLDataTreeCandidateFormatter EMPTY = new XMLDataTreeCandidateFormatter(TextParameters.EMPTY);
  22
  23     static final DataTreeCandidateFormatterFactory FACTORY = new DataTreeCandidateFormatterFactory(EMPTY) {
  24         @Override
  25         public XMLDataTreeCandidateFormatter getFormatter(final TextParameters textParams, final String xpathFilter)
  26                 throws XPathExpressionException {
  27             return new XMLDataTreeCandidateFormatter(textParams, xpathFilter);
  28         }
  29
  30         @Override
  31         public XMLDataTreeCandidateFormatter newFormatter(final TextParameters textParams) {
  32             return new XMLDataTreeCandidateFormatter(textParams);
  33         }
  34     };
  35
  36     private XMLDataTreeCandidateFormatter(final TextParameters textParams) {
  37         super(textParams);
  38     }
  39
  40     private XMLDataTreeCandidateFormatter(final TextParameters textParams, final String xpathFilter)
  41             throws XPathExpressionException {
  42         super(textParams, xpathFilter);
  43     }
  44
  45     @Override
  46     String createText(final TextParameters params, final EffectiveModelContext schemaContext,
  47             final List<DataTreeCandidate> input, final Instant now) throws Exception {
  48         final var writer = new StringWriter();
  49         boolean nonEmpty = false;
  50         try {
  51             final var xmlStreamWriter = NotificationFormatter.createStreamWriterWithNotification(writer, now);
  52             xmlStreamWriter.writeStartElement(XMLConstants.DEFAULT_NS_PREFIX, DATA_CHANGED_NOTIFICATION_ELEMENT,
  53                 DATA_CHANGED_NOTIFICATION_NS);
  54             xmlStreamWriter.writeDefaultNamespace(DATA_CHANGED_NOTIFICATION_NS);
  55
  56             final var serializer = new XmlDataTreeCandidateSerializer(schemaContext, xmlStreamWriter);
  57             for (var candidate : input) {
  58                 nonEmpty |= serializer.serialize(candidate, params);
  59             }
  60
  61             // data-changed-notification
  62             xmlStreamWriter.writeEndElement();
  63
  64             // notification
  65             xmlStreamWriter.writeEndElement();
  66             xmlStreamWriter.close();
  67         } catch (XMLStreamException e) {
  68             throw new IOException("Failed to write notification content", e);
  69         }
  70
  71         return nonEmpty ? writer.toString() : null;
  72     }
  73 }