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

   1 // Copyright 2007 Google Inc. All rights reserved.
   2
   3 package com.google.appengine.api.datastore;
   4
   5 import com.google.common.collect.Maps;
   6 import com.google.storage.onestore.v3.OnestoreEntity.EntityProto;
   7 import com.google.storage.onestore.v3.OnestoreEntity.Path;
   8 import com.google.storage.onestore.v3.OnestoreEntity.Reference;
   9
  10 import java.util.Collection;
  11 import java.util.Map;
  12
  13 /**
  14  * {@code EntityTranslator} contains the logic to translate an {@code
  15  * Entity} into the protocol buffers that are used to pass it to the
  16  * implementation of the API.
  17  *
  18  */
  19 public class EntityTranslator {
  20
  21   public static Entity createFromPb(EntityProto proto, Collection<Projection> projections) {
  22     Key key = KeyTranslator.createFromPb(proto.getKey());
  23
  24     Entity entity = new Entity(key);
  25     Map<String, Object> values = Maps.newHashMap();
  26     DataTypeTranslator.extractPropertiesFromPb(proto, values);
  27     for (Projection projection : projections) {
  28       entity.setProperty(projection.getName(), projection.getValue(values));
  29     }
  30     return entity;
  31   }
  32
  33   public static Entity createFromPb(EntityProto proto) {
  34     Key key = KeyTranslator.createFromPb(proto.getKey());
  35
  36     Entity entity = new Entity(key);
  37     DataTypeTranslator.extractPropertiesFromPb(proto, entity.getPropertyMap());
  38     return entity;
  39   }
  40
  41   public static Entity createFromPbBytes(byte[] pbBytes) {
  42     EntityProto proto = new EntityProto();
  43     boolean parsed = proto.mergeFrom(pbBytes);
  44     if (!parsed || !proto.isInitialized()) {
  45       throw new IllegalArgumentException("Could not parse EntityProto bytes");
  46     }
  47     return createFromPb(proto);
  48   }
  49
  50   public static EntityProto convertToPb(Entity entity) {
  51     Reference reference = KeyTranslator.convertToPb(entity.getKey());
  52
  53     EntityProto proto = new EntityProto();
  54     proto.setKey(reference);
  55
  56     Path entityGroup = proto.getMutableEntityGroup();
  57     Key key = entity.getKey();
  58     if (key.isComplete()) {
  59       entityGroup.addElement(reference.getPath().elements().get(0));
  60     }
  61
  62     DataTypeTranslator.addPropertiesToPb(entity.getPropertyMap(), proto);
  63     return proto;
  64   }
  65
  66   private EntityTranslator() {
  67   }
  68 }