在App Engine中按@id属性过滤Google Cloud Datastore实体

Question

I am trying to to a Query in App Engine based on the @id property of the entities and I keep getting this error

java.lang.IllegalArgumentException: __ key __ filter value must be a Key

this is how I am doing my Query

Filter f1 = new FilterPredicate("personId", FilterOperator.EQUAL,personId);
Filter f2 = new FilterPredicate(Entity.KEY_RESERVED_PROPERTY, FilterOperator.GREATER_THAN,newestCommentId);

Filter filter = CompositeFilterOperator.and(f1,f2);


Query<Record> query = ofy().load().type(Record.class).filter(filter)
                .limit(limit).order("-"+ Entity.KEY_RESERVED_PROPERTY);

I want to get everything > the last comment id that is sent to the app engine method

the id field in the entity is this

@Id
Long id;

I tried using the id first but then I got an error saying that you cannot use a file who has @id and maybe I meant __ key __

so how do I execute this query?

Answer 1

You need to use a Key , not an id, in your filter. You can create a Key from this id and then pass to your filter.

Note that unless you increment IDs yourself, they are not guaranteed to grow as you add more entities.