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- Method resolution order:
- Token
- google.appengine.ext.db.Model
- __builtin__.object
Data descriptors defined here:
- t
- A byte string that can be longer than 500 bytes.
Methods inherited from google.appengine.ext.db.Model:
- __init__(self, parent=None, key_name=None, _app=None, _from_entity=False, **kwds)
- Creates a new instance of this model.
To create a new entity, you instantiate a model and then call put(),
which saves the entity to the datastore:
person = Person()
person.name = 'Bret'
person.put()
You can initialize properties in the model in the constructor with keyword
arguments:
person = Person(name='Bret')
We initialize all other properties to the default value (as defined by the
properties in the model definition) if they are not provided in the
constructor.
Args:
parent: Parent instance for this instance or None, indicating a top-
level instance.
key_name: Name for new model instance.
_from_entity: Intentionally undocumented.
kwds: Keyword arguments mapping to properties of model. Also:
key: Key instance for this instance, if provided makes parent and
key_name redundant (they do not need to be set but if they are
they must match the key).
- delete(self, **kwargs)
- Deletes this entity from the datastore.
Args:
config: datastore_rpc.Configuration to use for this request.
Raises:
TransactionFailedError if the data could not be committed.
- dynamic_properties(self)
- Returns a list of all dynamic properties defined for instance.
- has_key(self)
- Determine if this model instance has a complete key.
When not using a fully self-assigned Key, ids are not assigned until the
data is saved to the Datastore, but instances with a key name always have
a full key.
Returns:
True if the object has been persisted to the datastore or has a key
or has a key_name, otherwise False.
- instance_properties(self)
- Alias for dyanmic_properties.
- is_saved(self)
- Determine if entity is persisted in the datastore.
New instances of Model do not start out saved in the data. Objects which
are saved to or loaded from the Datastore will have a True saved state.
Returns:
True if object has been persisted to the datastore, otherwise False.
- key(self)
- Unique key for this entity.
This property is only available if this entity is already stored in the
datastore or if it has a full key, so it is available if this entity was
fetched returned from a query, or after put() is called the first time
for new entities, or if a complete key was given when constructed.
Returns:
Datastore key of persisted entity.
Raises:
NotSavedError when entity is not persistent.
- parent(self)
- Get the parent of the model instance.
Returns:
Parent of contained entity or parent provided in constructor, None if
instance has no parent.
- parent_key(self)
- Get the parent's key.
This method is useful for avoiding a potential fetch from the datastore
but still get information about the instances parent.
Returns:
Parent key of entity, None if there is no parent.
- put(self, **kwargs)
- Writes this model instance to the datastore.
If this instance is new, we add an entity to the datastore.
Otherwise, we update this instance, and the key will remain the
same.
Args:
config: datastore_rpc.Configuration to use for this request.
Returns:
The key of the instance (either the existing key or a new key).
Raises:
TransactionFailedError if the data could not be committed.
- save = put(self, **kwargs)
- Writes this model instance to the datastore.
If this instance is new, we add an entity to the datastore.
Otherwise, we update this instance, and the key will remain the
same.
Args:
config: datastore_rpc.Configuration to use for this request.
Returns:
The key of the instance (either the existing key or a new key).
Raises:
TransactionFailedError if the data could not be committed.
- to_xml(self, _entity_class=<class 'google.appengine.api.datastore.Entity'>)
- Generate an XML representation of this model instance.
atom and gd:namespace properties are converted to XML according to their
respective schemas. For more information, see:
http://www.atomenabled.org/developers/syndication/
http://code.google.com/apis/gdata/common-elements.html
Class methods inherited from google.appengine.ext.db.Model:
- all(cls, **kwds) from google.appengine.ext.db.PropertiedClass
- Returns a query over all instances of this model from the datastore.
Returns:
Query that will retrieve all instances from entity collection.
- entity_type(cls) from google.appengine.ext.db.PropertiedClass
- Soon to be removed alias for kind.
- fields(cls) from google.appengine.ext.db.PropertiedClass
- Soon to be removed alias for properties.
- from_entity(cls, entity) from google.appengine.ext.db.PropertiedClass
- Converts the entity representation of this model to an instance.
Converts datastore.Entity instance to an instance of cls.
Args:
entity: Entity loaded directly from datastore.
Raises:
KindError when cls is incorrect model for entity.
- get(cls, keys, **kwargs) from google.appengine.ext.db.PropertiedClass
- Fetch instance from the datastore of a specific Model type using key.
We support Key objects and string keys (we convert them to Key objects
automatically).
Useful for ensuring that specific instance types are retrieved from the
datastore. It also helps that the source code clearly indicates what
kind of object is being retreived. Example:
story = Story.get(story_key)
Args:
keys: Key within datastore entity collection to find; or string key;
or list of Keys or string keys.
config: datastore_rpc.Configuration to use for this request.
Returns:
If a single key was given: a Model instance associated with key
for provided class if it exists in the datastore, otherwise
None; if a list of keys was given: a list whose items are either
a Model instance or None.
Raises:
KindError if any of the retreived objects are not instances of the
type associated with call to 'get'.
- get_by_id(cls, ids, parent=None, **kwargs) from google.appengine.ext.db.PropertiedClass
- Get instance of Model class by id.
Args:
key_names: A single id or a list of ids.
parent: Parent of instances to get. Can be a model or key.
config: datastore_rpc.Configuration to use for this request.
- get_by_key_name(cls, key_names, parent=None, **kwargs) from google.appengine.ext.db.PropertiedClass
- Get instance of Model class by its key's name.
Args:
key_names: A single key-name or a list of key-names.
parent: Parent of instances to get. Can be a model or key.
config: datastore_rpc.Configuration to use for this request.
- get_or_insert(cls, key_name, **kwds) from google.appengine.ext.db.PropertiedClass
- Transactionally retrieve or create an instance of Model class.
This acts much like the Python dictionary setdefault() method, where we
first try to retrieve a Model instance with the given key name and parent.
If it's not present, then we create a new instance (using the *kwds
supplied) and insert that with the supplied key name.
Subsequent calls to this method with the same key_name and parent will
always yield the same entity (though not the same actual object instance),
regardless of the *kwds supplied. If the specified entity has somehow
been deleted separately, then the next call will create a new entity and
return it.
If the 'parent' keyword argument is supplied, it must be a Model instance.
It will be used as the parent of the new instance of this Model class if
one is created.
This method is especially useful for having just one unique entity for
a specific identifier. Insertion/retrieval is done transactionally, which
guarantees uniqueness.
Example usage:
class WikiTopic(db.Model):
creation_date = db.DatetimeProperty(auto_now_add=True)
body = db.TextProperty(required=True)
# The first time through we'll create the new topic.
wiki_word = 'CommonIdioms'
topic = WikiTopic.get_or_insert(wiki_word,
body='This topic is totally new!')
assert topic.key().name() == 'CommonIdioms'
assert topic.body == 'This topic is totally new!'
# The second time through will just retrieve the entity.
overwrite_topic = WikiTopic.get_or_insert(wiki_word,
body='A totally different message!')
assert topic.key().name() == 'CommonIdioms'
assert topic.body == 'This topic is totally new!'
Args:
key_name: Key name to retrieve or create.
**kwds: Keyword arguments to pass to the constructor of the model class
if an instance for the specified key name does not already exist. If
an instance with the supplied key_name and parent already exists, the
rest of these arguments will be discarded.
Returns:
Existing instance of Model class with the specified key_name and parent
or a new one that has just been created.
Raises:
TransactionFailedError if the specified Model instance could not be
retrieved or created transactionally (due to high contention, etc).
- gql(cls, query_string, *args, **kwds) from google.appengine.ext.db.PropertiedClass
- Returns a query using GQL query string.
See appengine/ext/gql for more information about GQL.
Args:
query_string: properly formatted GQL query string with the
'SELECT * FROM <entity>' part omitted
*args: rest of the positional arguments used to bind numeric references
in the query.
**kwds: dictionary-based arguments (for named parameters).
- kind(cls) from google.appengine.ext.db.PropertiedClass
- Returns the datastore kind we use for this model.
We just use the name of the model for now, ignoring potential collisions.
- properties(cls) from google.appengine.ext.db.PropertiedClass
- Returns a dictionary of all the properties defined for this model.
Static methods inherited from google.appengine.ext.db.Model:
- __new__(*args, **unused_kwds)
- Allow subclasses to call __new__() with arguments.
Do NOT list 'cls' as the first argument, or in the case when
the 'unused_kwds' dictionary contains the key 'cls', the function
will complain about multiple argument values for 'cls'.
Raises:
TypeError if there are no positional arguments.
Data descriptors inherited from google.appengine.ext.db.Model:
- __dict__
- dictionary for instance variables (if defined)
- __weakref__
- list of weak references to the object (if defined)
Data and other attributes inherited from google.appengine.ext.db.Model:
- __metaclass__ = <class 'google.appengine.ext.db.PropertiedClass'>
- Meta-class for initializing Model classes properties.
Used for initializing Properties defined in the context of a model.
By using a meta-class much of the configuration of a Property
descriptor becomes implicit. By using this meta-class, descriptors
that are of class Model are notified about which class they
belong to and what attribute they are associated with and can
do appropriate initialization via __property_config__.
Duplicate properties are not permitted.
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