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

   1 package com.google.appengine.api.datastore;
   2
   3 import static com.google.appengine.api.datastore.DataTypeTranslator.getComparablePropertyValue;
   4
   5 import com.google.apphosting.datastore.DatastoreV3Pb.Query.Filter;
   6 import com.google.apphosting.datastore.DatastoreV3Pb.Query.Order;
   7
   8 import java.util.ArrayList;
   9 import java.util.Collection;
  10 import java.util.Collections;
  11 import java.util.List;
  12
  13 /**
  14  * A comparator with the same ordering as {@link EntityProtoComparators} which uses
  15  * Entity objects rather than protos.
  16  */
  17 class EntityComparator extends BaseEntityComparator<Entity> {
  18
  19   EntityComparator(List<Order> orders) {
  20     super(orders, Collections.<Filter>emptyList());
  21   }
  22
  23   @Override
  24   List<Comparable<Object>> getComparablePropertyValues(Entity entity, String propertyName) {
  25     Object prop;
  26     if (propertyName.equals(Entity.KEY_RESERVED_PROPERTY)) {
  27       prop = entity.getKey();
  28     } else if (!entity.hasProperty(propertyName)) {
  29       return null;
  30     } else {
  31       prop = entity.getProperty(propertyName);
  32     }
  33     if (prop instanceof Collection<?>) {
  34       Collection<?> props = (Collection<?>) prop;
  35       if (props.isEmpty()) {
  36         return Collections.singletonList(null);
  37       }
  38       List<Comparable<Object>> comparableProps = new ArrayList<>(props.size());
  39       for (Object curProp : props) {
  40         comparableProps.add(getComparablePropertyValue(curProp));
  41       }
  42       return comparableProps;
  43     } else {
  44       return Collections.singletonList(getComparablePropertyValue(prop));
  45     }
  46   }
  47 }