Source code for google.cloud.datastore.entity

# Copyright 2014 Google Inc.
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#     http://www.apache.org/licenses/LICENSE-2.0
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"""Class for representing a single entity in the Cloud Datastore."""


from google.cloud._helpers import _ensure_tuple_or_list


[docs]class Entity(dict): """Entities are akin to rows in a relational database An entity storing the actual instance of data. Each entity is officially represented with a :class:`google.cloud.datastore.key.Key` class, however it is possible that you might create an Entity with only a partial Key (that is, a Key with a Kind, and possibly a parent, but without an ID). In such a case, the datastore service will automatically assign an ID to the partial key. Entities in this API act like dictionaries with extras built in that allow you to delete or persist the data stored on the entity. Entities are mutable and act like a subclass of a dictionary. This means you could take an existing entity and change the key to duplicate the object. Use :func:`google.cloud.datastore.get` to retrieve an existing entity. >>> from google.cloud import datastore >>> client = datastore.Client() >>> client.get(key) <Entity[{'kind': 'EntityKind', id: 1234}] {'property': 'value'}> You can the set values on the entity just like you would on any other dictionary. >>> entity['age'] = 20 >>> entity['name'] = 'JJ' >>> entity <Entity[{'kind': 'EntityKind', id: 1234}] {'age': 20, 'name': 'JJ'}> And you can convert an entity to a regular Python dictionary with the ``dict`` builtin: >>> dict(entity) {'age': 20, 'name': 'JJ'} .. note:: When saving an entity to the backend, values which are "text" (``unicode`` in Python2, ``str`` in Python3) will be saved using the 'text_value' field, after being encoded to UTF-8. When retrieved from the back-end, such values will be decoded to "text" again. Values which are "bytes" (``str`` in Python2, ``bytes`` in Python3), will be saved using the 'blob_value' field, without any decoding / encoding step. :type key: :class:`google.cloud.datastore.key.Key` :param key: Optional key to be set on entity. :type exclude_from_indexes: tuple of string :param exclude_from_indexes: Names of fields whose values are not to be indexed for this entity. """ def __init__(self, key=None, exclude_from_indexes=()): super(Entity, self).__init__() self.key = key self._exclude_from_indexes = set(_ensure_tuple_or_list( 'exclude_from_indexes', exclude_from_indexes)) # NOTE: This will be populated when parsing a protobuf in # google.cloud.datastore.helpers.entity_from_protobuf. self._meanings = {} def __eq__(self, other): """Compare two entities for equality. Entities compare equal if their keys compare equal and their properties compare equal. :rtype: boolean :returns: True if the entities compare equal, else False. """ if not isinstance(other, Entity): return False return (self.key == other.key and self._exclude_from_indexes == other._exclude_from_indexes and self._meanings == other._meanings and super(Entity, self).__eq__(other)) def __ne__(self, other): """Compare two entities for inequality. Entities compare equal if their keys compare equal and their properties compare equal. :rtype: boolean :returns: False if the entities compare equal, else True. """ return not self.__eq__(other) @property def kind(self): """Get the kind of the current entity. .. note:: This relies entirely on the :class:`google.cloud.datastore.key.Key` set on the entity. That means that we're not storing the kind of the entity at all, just the properties and a pointer to a Key which knows its Kind. """ if self.key: return self.key.kind @property def exclude_from_indexes(self): """Names of fields which are *not* to be indexed for this entity. :rtype: sequence of field names :returns: The set of fields excluded from indexes. """ return frozenset(self._exclude_from_indexes) def __repr__(self): if self.key: return '<Entity%s %s>' % (self.key.path, super(Entity, self).__repr__()) else: return '<Entity %s>' % (super(Entity, self).__repr__())