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