Google App Engine Ancestor Query
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12-06-2021 - |
Pergunta
I am apparently confused as to how the GAE ancestor query should work. My understanding was that an ancestor query should return all descendent generations, not just immediate children. Yet if I modify the example from the Developer Guide as follows, I retrieve only the immediate children, never the grandchild. What am I missing?
Entity person = new Entity("Person", "tom");
Entity weddingPhoto = new Entity("Photo", person.getKey());
weddingPhoto.setProperty("imageUrl",
"http://domain.com/some/path/to/wedding_photo.jpg");
Entity babyPhoto = new Entity("Photo", person.getKey());
babyPhoto.setProperty("imageUrl",
"http://domain.com/some/path/to/baby_photo.jpg");
// add this grandchild:
Entity grandbabyPhoto = new Entity("Photo", babyPhoto.getKey());
grandbabyPhoto.setProperty("imageUrl",
"http://domain.com/some/path/to/grandbabyPhoto.jpg");
Entity dancePhoto = new Entity("Photo", person.getKey());
dancePhoto.setProperty("imageUrl",
"http://domain.com/some/path/to/dance_photo.jpg");
Entity campingPhoto = new Entity("Photo");
campingPhoto.setProperty("imageUrl",
"http://domain.com/some/path/to/camping_photo.jpg");
getDatastore().put(
java.util.Arrays.asList(person, weddingPhoto, babyPhoto, dancePhoto, campingPhoto));
Query userPhotosQuery = new Query("Photo");
userPhotosQuery.setAncestor(person.getKey());
// This returns weddingPhoto, babyPhoto and dancePhoto, but
// not grandbabyPhoto --- why???
List<Entity> results =
getDatastore().prepare(userPhotosQuery).asList(
FetchOptions.Builder.withDefaults());
Thanks very much for any help you can provide!
Solução
Because your put(..)
statement does not contain grandbabyPhoto
, so it does not get saved.
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