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App Engine Python SDK
v1.6.9 rev.445
The Python runtime is available as an experimental Preview feature.
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Public Member Functions | |
def | __init__ |
def | adapter |
def | config |
def | is_pending |
def | get_pending_rpcs |
def | get_datastore_type |
def | wait_for_all_pending_rpcs |
def | check_rpc_success |
def | get |
def | async_get |
def | get_indexes |
def | async_get_indexes |
def | put |
def | async_put |
def | delete |
def | async_delete |
def | begin_transaction |
def | async_begin_transaction |
Datastore connection base class. NOTE: Do not instantiate this class; use Connection or TransactionalConnection instead. This is not a traditional database connection -- with App Engine, in the end the connection is always implicit in the process state. There is also no intent to be compatible with PEP 249 (Python's Database-API). But it is a useful abstraction to have an explicit object that manages the database interaction, and especially transactions. Other settings related to the App Engine datastore are also stored here (e.g. the RPC timeout). A similar class in the Java API to the App Engine datastore is DatastoreServiceConfig (but in Java, transaction state is always held by the current thread). To use transactions, call connection.new_transaction(). This returns a new connection (an instance of the TransactionalConnection subclass) which you should use for all operations in the transaction. This model supports multiple unrelated concurrent transactions (but not nested transactions as this concept is commonly understood in the relational database world). When the transaction is done, call .commit() or .rollback() on the transactional connection. If .commit() returns False, the transaction failed and none of your operations made it to the datastore; if it returns True, all your operations were committed. The transactional connection cannot be used once .commit() or .rollback() is called. Transactions are created lazily. The first operation that requires a transaction handle will issue the low-level BeginTransaction request and wait for it to return. Transactions keep track of the entity group. All operations within a transaction must use the same entity group. An entity group (currently) comprises an app id, a namespace, and a top-level key (a kind and an id or name). The first operation performed determines the entity group. There is some special-casing when the first operation is a put() of an entity with an incomplete key; in this case the entity group is determined after the operation returns. NOTE: the datastore stubs in the dev_appserver currently support only a single concurrent transaction. Specifically, the (old) file stub locks up if an attempt is made to start a new transaction while a transaction is already in use, whereas the sqlite stub fails an assertion.
def google.appengine.datastore.datastore_rpc.BaseConnection.__init__ | ( | self, | |
adapter = None , |
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config = None , |
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_api_version = _DATASTORE_V3 |
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) |
Constructor. All arguments should be specified as keyword arguments. Args: adapter: Optional AbstractAdapter subclass instance; default IdentityAdapter. config: Optional Configuration object.
def google.appengine.datastore.datastore_rpc.BaseConnection.adapter | ( | self | ) |
The adapter used by this connection.
def google.appengine.datastore.datastore_rpc.BaseConnection.async_begin_transaction | ( | self, | |
config, | |||
app | |||
) |
Asynchronous BeginTransaction operation. Args: config: A configuration object or None. Defaults are taken from the connection's default configuration. app: Application ID. Returns: A MultiRpc object.
def google.appengine.datastore.datastore_rpc.BaseConnection.async_delete | ( | self, | |
config, | |||
keys, | |||
extra_hook = None |
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) |
Asynchronous Delete operation. Args: config: A Configuration object or None. Defaults are taken from the connection's default configuration. keys: An iterable of user-level key objects. extra_hook: Optional function to be called once the RPC has completed. Returns: A MultiRpc object.
def google.appengine.datastore.datastore_rpc.BaseConnection.async_get | ( | self, | |
config, | |||
keys, | |||
extra_hook = None |
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) |
Asynchronous Get operation. Args: config: A Configuration object or None. Defaults are taken from the connection's default configuration. keys: An iterable of user-level key objects. extra_hook: Optional function to be called on the result once the RPC has completed. Returns: A MultiRpc object.
def google.appengine.datastore.datastore_rpc.BaseConnection.async_get_indexes | ( | self, | |
config, | |||
extra_hook = None , |
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_app = None |
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) |
Asynchronous get indexes operation. Args: config: A Configuration object or None. Defaults are taken from the connection's default configuration. extra_hook: Optional function to be called once the RPC has completed. Returns: A MultiRpc object.
def google.appengine.datastore.datastore_rpc.BaseConnection.async_put | ( | self, | |
config, | |||
entities, | |||
extra_hook = None |
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) |
Asynchronous Put operation. Args: config: A Configuration object or None. Defaults are taken from the connection's default configuration. entities: An iterable of user-level entity objects. extra_hook: Optional function to be called on the result once the RPC has completed. Returns: A MultiRpc object. NOTE: If any of the entities has an incomplete key, this will *not* patch up those entities with the complete key.
def google.appengine.datastore.datastore_rpc.BaseConnection.begin_transaction | ( | self, | |
app | |||
) |
Syncnronous BeginTransaction operation. NOTE: In most cases the new_transaction() method is preferred, since that returns a TransactionalConnection object which will begin the transaction lazily. Args: app: Application ID. Returns: An object representing a transaction or None.
def google.appengine.datastore.datastore_rpc.BaseConnection.check_rpc_success | ( | self, | |
rpc | |||
) |
Check for RPC success and translate exceptions. This wraps rpc.check_success() and should be called instead of that. This also removes the RPC from the list of pending RPCs, once it has completed. Args: rpc: A UserRPC or MultiRpc object. Raises: Nothing if the call succeeded; various datastore_errors.Error subclasses if ApplicationError was raised by rpc.check_success().
def google.appengine.datastore.datastore_rpc.BaseConnection.config | ( | self | ) |
The default configuration used by this connection.
def google.appengine.datastore.datastore_rpc.BaseConnection.delete | ( | self, | |
keys | |||
) |
Synchronous Delete operation. Args: keys: An iterable of user-level key objects. Returns: None.
def google.appengine.datastore.datastore_rpc.BaseConnection.get | ( | self, | |
keys | |||
) |
Synchronous Get operation. Args: keys: An iterable of user-level key objects. Returns: A list of user-level entity objects and None values, corresponding 1:1 to the argument keys. A None means there is no entity for the corresponding key.
def google.appengine.datastore.datastore_rpc.BaseConnection.get_datastore_type | ( | self, | |
app = None |
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) |
Tries to get the datastore type for the given app. This function is only guaranteed to return something other than UNKNOWN_DATASTORE when running in production and querying the current app.
def google.appengine.datastore.datastore_rpc.BaseConnection.get_indexes | ( | self | ) |
Synchronous get indexes operation. Returns: user-level indexes representation
def google.appengine.datastore.datastore_rpc.BaseConnection.get_pending_rpcs | ( | self | ) |
Return (a copy of) the list of currently pending RPCs.
def google.appengine.datastore.datastore_rpc.BaseConnection.is_pending | ( | self, | |
rpc | |||
) |
Check whether an RPC object is currently pending. Note that 'pending' in this context refers to an RPC associated with this connection for which _remove_pending() hasn't been called yet; normally this is called by check_rpc_success() which itself is called by the various result hooks. A pending RPC may be in the RUNNING or FINISHING state. If the argument is a MultiRpc object, this returns true if at least one of its wrapped RPCs is pending.
def google.appengine.datastore.datastore_rpc.BaseConnection.put | ( | self, | |
entities | |||
) |
Synchronous Put operation. Args: entities: An iterable of user-level entity objects. Returns: A list of user-level key objects, corresponding 1:1 to the argument entities. NOTE: If any of the entities has an incomplete key, this will *not* patch up those entities with the complete key.
def google.appengine.datastore.datastore_rpc.BaseConnection.wait_for_all_pending_rpcs | ( | self | ) |
Wait for all currently pending RPCs to complete.