java/src/main/com/google/appengine/api/datastore/KeyTranslator.java

   1 // Copyright 2007 Google Inc. All rights reserved.
   2
   3 package com.google.appengine.api.datastore;
   4
   5 import com.google.storage.onestore.v3.OnestoreEntity.Path;
   6 import com.google.storage.onestore.v3.OnestoreEntity.Path.Element;
   7 import com.google.storage.onestore.v3.OnestoreEntity.Reference;
   8
   9 import java.util.Collections;
  10 import java.util.List;
  11
  12 /**
  13  * {@code KeyTranslator} contains the logic to translate a {@link Key}
  14  * into the protocol buffers that are used to pass it to the
  15  * implementation of the API.
  16  *
  17  */
  18 class KeyTranslator {
  19
  20   public static Key createFromPb(Reference reference) {
  21     Key parentKey = null;
  22     Path path = reference.getPath();
  23     List<Element> elements = path.elements();
  24     if (elements.isEmpty()) {
  25       throw new IllegalArgumentException("Invalid Key PB: no elements.");
  26     }
  27
  28     AppIdNamespace appIdNamespace = new AppIdNamespace(reference.getApp(),
  29         reference.hasNameSpace() ? reference.getNameSpace() : "");
  30
  31     for (Element e : elements) {
  32       String kind = e.getType();
  33       if (e.hasName() && e.hasId()) {
  34         throw new IllegalArgumentException("Invalid Key PB: both id and name are set.");
  35       } else if (e.hasName()) {
  36         parentKey = new Key(kind, parentKey, Key.NOT_ASSIGNED, e.getName(), appIdNamespace);
  37       } else if (e.hasId()) {
  38         parentKey = new Key(kind, parentKey, e.getId(), null, appIdNamespace);
  39       } else {
  40         parentKey = new Key(kind, parentKey, Key.NOT_ASSIGNED, null, appIdNamespace);
  41       }
  42     }
  43
  44     return parentKey;
  45   }
  46
  47   public static Reference convertToPb(Key key) {
  48     Reference reference = new Reference();
  49
  50     reference.setApp(key.getAppId());
  51     String nameSpace = key.getNamespace();
  52     if (!nameSpace.isEmpty()) {
  53       reference.setNameSpace(nameSpace);
  54     }
  55
  56     Path path = reference.getMutablePath();
  57     while (key != null) {
  58       Element pathElement = new Element();
  59       pathElement.setType(key.getKind());
  60       if (key.getName() != null) {
  61         pathElement.setName(key.getName());
  62       } else if (key.getId() != Key.NOT_ASSIGNED) {
  63         pathElement.setId(key.getId());
  64       }
  65       path.addElement(pathElement);
  66       key = key.getParent();
  67     }
  68     Collections.reverse(path.mutableElements());
  69     return reference;
  70   }
  71
  72   public static void updateKey(Reference reference, Key key) {
  73
  74     if (key.getName() == null) {
  75       Path path = reference.getPath();
  76       key.setId(path.getElement(path.elementSize() - 1).getId());
  77     }
  78   }
  79
  80   KeyTranslator() { }
  81 }