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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"datastore: Nested entity parsing fails","articleBody":"https://cloud.google.com/appengine/docs/python/ndb/properties#structured\n\nIn order to write entities with structured properties, I tried to read them first, to figure out the format.\n\nFirst `StructuredProperty`.\n\n``` Python\nclass Item_Meta(ndb.Model):\n    xy = ndb.IntegerProperty(repeated = True)\n\nclass Item(ndb.Model):\n    meta = ndb.StructuredProperty(Item_Meta)\n\nitem = Item()\nitem.meta = Item_Meta(xy = [100, 200])\nitem.put() # 5710239819104256\n```\n\n``` Python\n\u003e\u003e\u003e datastore.api.get([datastore.Key('Item', 5710239819104256)])\n[\u003cEntity[{'kind': u'Item', 'id': 5710239819104256L}] {u'meta.xy': [100L, 200L]}\u003e]\n```\n\nNext `LocalStructuredProperty`.\n\n\u003e Although a `StructuredProperty` can be repeated and a `StructuredProperty` can contain another `StructuredProperty`, beware: if one structured property contains another, only one of them can be repeated. A work-around is to use `LocalStructuredProperty`, which does not have this constraint.\n\n``` Python\nclass Item_Meta(ndb.Model):\n    xy = ndb.IntegerProperty(repeated = True)\n\nclass Item(ndb.Model):\n    meta = ndb.LocalStructuredProperty(Item_Meta, repeated = True)\n\nitem = Item()\nitem.meta = [Item_Meta(xy = [100, 200])]\nitem.put() # 6217263929622528\n```\n\n``` Python\n\u003e\u003e\u003e datastore.api.get([datastore.Key('Item', 6217263929622528)])\nTraceback (most recent call last):\n  File \"\u003cstdin\u003e\", line 1, in \u003cmodule\u003e\n  File \"/home/user/.local/lib/python2.7/site-packages/gcloud/datastore/api.py\", line 229, in get\n    entities.append(helpers.entity_from_protobuf(entity_pb))\n  File \"/home/user/.local/lib/python2.7/site-packages/gcloud/datastore/helpers.py\", line 53, in entity_from_protobuf\n    value = _get_value_from_property_pb(property_pb)\n  File \"/home/user/.local/lib/python2.7/site-packages/gcloud/datastore/helpers.py\", line 237, in _get_value_from_property_pb\n    return _get_value_from_value_pb(property_pb.value)\n  File \"/home/user/.local/lib/python2.7/site-packages/gcloud/datastore/helpers.py\", line 217, in _get_value_from_value_pb\n    result = [_get_value_from_value_pb(x) for x in value_pb.list_value]\n  File \"/home/user/.local/lib/python2.7/site-packages/gcloud/datastore/helpers.py\", line 214, in _get_value_from_value_pb\n    result = entity_from_protobuf(value_pb.entity_value)\n  File \"/home/user/.local/lib/python2.7/site-packages/gcloud/datastore/helpers.py\", line 48, in entity_from_protobuf\n    key = key_from_protobuf(pb.key)\n  File \"/home/user/.local/lib/python2.7/site-packages/gcloud/datastore/helpers.py\", line 105, in key_from_protobuf\n    return Key(*path_args, namespace=namespace, dataset_id=dataset_id)\n  File \"/home/user/.local/lib/python2.7/site-packages/gcloud/datastore/key.py\", line 76, in __init__\n    self._path = self._combine_args()\n  File \"/home/user/.local/lib/python2.7/site-packages/gcloud/datastore/key.py\", line 133, in _combine_args\n    child_path = self._parse_path(self._flat_path)\n  File \"/home/user/.local/lib/python2.7/site-packages/gcloud/datastore/key.py\", line 94, in _parse_path\n    raise ValueError('Key path must not be empty.')\nValueError: Key path must not be empty.\n```\n","author":{"url":"https://github.com/pdknsk","@type":"Person","name":"pdknsk"},"datePublished":"2015-02-11T00:18:19.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/616/google-cloud-python/issues/616"}