java - 如何在 Google Cloud Datastore 中添加数组属性值

Question

如何将字符串或整数数组添加到属性值？这是我的代码，但它不起作用

   while(i<ValueArray.length)
                {               
                entityBuilder.addProperty(Property.newBuilder()
                      .setName(name))
                       .setValue(Value.newBuilder().setStringValue(ValueArray[i])));
                i++;}

提前谢谢您，

Answer 1

您可以为此使用列表值:

Value.Builder listValueBuilder = Value.newBuilder();
for (String value : values) {
  listValueBuilder.addListValue(Value.newBuilder().setStringValue(value));
}
entityBuilder.addProperty(Property.newBuilder()
    .setName(name)
    .setValue(listValueBuilder));

或者，使用 DatastoreHelper 中的便捷方法:

Value.Builder[] valueArray = new Value.Builder[values.length];
for (int i = 0; i < values.length; i++) {
  valueArray[i] = DatastoreHelper.makeValue(values[i]);
}
entityBuilder.addProperty(
    DatastoreHelper.makeProperty(name, DatastoreHelper.makeValue(valueArray)));

并检索值:

for (Property property : entity.getPropertyList()) {
  // Find the list property by name.
  if (property.getName().equals(name)) {
    for (Value value : property.getValue().getListValueList()) {
      // Print each string value from the list value.
      System.out.println(value.getStringValue());
    }
  }
}

或者，再次使用DatastoreHelper:

Map<String, Value> propertyMap = DatastoreHelper.getPropertyMap(entity);
for (Value value : propertyMap.get(name).getListValueList()) {
  // Print each string value from the list value.
  System.out.println(value.getStringValue());
}