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

   1 // Copyright 2012 Google Inc. All Rights Reserved.
   2
   3 package com.google.appengine.api.datastore;
   4
   5 import com.google.common.base.Objects;
   6
   7 import java.util.HashMap;
   8 import java.util.Map;
   9
  10 /**
  11  * A property value containing embedded entity properties (and optionally a {@link Key}).
  12  *
  13  * This class is similar to {@link Entity}, but differs in the following ways:
  14  * <ul>
  15  * <li>{@link #equals(Object)} and {@link #hashCode()} compare the embedded
  16  * properties in addition to the {@link Key}.
  17  * <li>It is not queriable when stored in the datastore.
  18  * <li>A {@link Key} is optional.
  19  * <li>{@link Key Keys} without a name or id are considered equal if all other
  20  * aspects of the keys are equal (as they will not be assigned IDs by the
  21  * datastore when embedded).
  22  * </ul>
  23  *
  24  * To convert from an {@link Entity} use:
  25  * <pre> {@code
  26  * EmbeddedEntity sv = new EmbeddedEntity();
  27  * sv.setKey(entity.getKey())
  28  * sv.setPropertiesFrom(entity)
  29  * }</pre>
  30  * To convert to an {@link Entity} use:
  31  * <pre> {@code
  32  * Entity entity = new Entity(sv.getKey())
  33  * entity.setPropertiesFrom(sv);
  34  * }</pre>
  35  *
  36  */
  37 public final class EmbeddedEntity extends PropertyContainer {
  38   private Key key = null;
  39   private final Map<String, Object> propertyMap = new HashMap<String, Object>();
  40
  41   /**
  42    * @return the key or {@code null}.
  43    */
  44   public Key getKey() {
  45     return key;
  46   }
  47
  48   /**
  49    * @param key the key to set
  50    */
  51   public void setKey(Keykey) {
  52     this.key = key;
  53   }
  54
  55   @Override
  56   Map<String, Object> getPropertyMap() {
  57     return propertyMap;
  58   }
  59
  60   @Override
  61   public EmbeddedEntity clone() {
  62     EmbeddedEntity result = new EmbeddedEntity();
  63     result.setKey(key);
  64     result.setPropertiesFrom(this);
  65     return result;
  66   }
  67
  68   @Override
  69   public String toString() {
  70     StringBuilder builder = new StringBuilder('<');
  71     builder.append(getClass().getName());
  72     if (key != null) {
  73       builder.append(" [").append(key).append(']');
  74     }
  75     builder.append(":\n");
  76     appendPropertiesTo(builder);
  77     builder.append(">\n");
  78     return builder.toString();
  79   }
  80
  81   @Override
  82   public int hashCode() {
  83     return Objects.hashCode(key, propertyMap);
  84   }
  85
  86   @Override
  87   public boolean equals(Object obj) {
  88     if (this == obj) return true;
  89     if (!(obj instanceof EmbeddedEntity)) return false;
  90     EmbeddedEntity other = (EmbeddedEntity) obj;
  91     if (!propertyMap.equals(other.propertyMap)) return false;
  92     return key == null ? other.key == null : key.equals(other.key, false);
  93   }
  94 }