Python 3.9 is now generally available.

google.appengine.ext.ndb.Context

Inherits From: expected_type

Methods

allocate_ids

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call_on_commit

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Call a callback upon successful commit of a transaction.

If not in a transaction, the callback is called immediately.

In a transaction, multiple callbacks may be registered and will be called once the transaction commits, in the order in which they were registered. If the transaction fails, the callbacks will not be called.

If the callback raises an exception, it bubbles up normally. This means:

  • If the callback is called immediately, any exception it raises will bubble up immediately.
  • If the call is postponed until commit, remaining callbacks will be skipped and the exception will bubble up through the transaction() call. However, the transaction is already committed at that point.

clear_cache

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Clears the in-memory cache.

NOTE: This does not affect memcache.

default_cache_policy

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Default cache policy.

This defers to _use_cache on the Model class.

Args
key Key instance.

Returns
A bool or None.

default_datastore_policy

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Default Datastore policy.

This defers to _use_datastore on the Model class.

Args
key Key instance.

Returns
A bool or None.

default_memcache_policy

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Default Memcache policy.

This defers to _use_memcache on the Model class.

Args
key Key instance.

Returns
A bool or None.

default_memcache_timeout_policy

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Default Memcache timeout policy.

This defers to _memcache_timeout on the Model class.

Args
key Key instance.

Returns
Memcache timeout to use (integer), or None.

delete

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flush

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get

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Returns a Model instance given the entity key.

It will use the context cache if the cache policy for the given key is enabled.

Args
key Key instance.
**ctx_options Context options.

Returns
A Model instance if the key exists in the datastore; None otherwise.

get_cache_policy

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Return the current context cache policy function.

Returns
A function that accepts a Key instance as argument and returns a bool indicating if it should be cached. May be None.

get_datastore_policy

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Return the current context datastore policy function.

Returns
A function that accepts a Key instance as argument and returns a bool indicating if it should use the datastore. May be None.

get_indexes

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get_memcache_policy

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Return the current memcache policy function.

Returns
A function that accepts a Key instance as argument and returns a bool indicating if it should be cached. May be None.

get_memcache_timeout_policy

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Return the current policy function for memcache timeout (expiration).

in_transaction

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Return whether a transaction is currently active.

iter_query

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map_query

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memcache_add

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memcache_cas

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memcache_decr

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memcache_delete

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memcache_get

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An auto-batching wrapper for memcache.get() or .get_multi().

Args
key Key to set. This must be a string; no prefix is applied.
for_cas If True, request and store CAS ids on the Context.
namespace Optional namespace.
deadline Optional deadline for the RPC.

Returns
A Future (!) whose return value is the value retrieved from memcache, or None.

memcache_gets

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memcache_incr

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memcache_replace

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memcache_set

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put

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set_cache_policy

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Set the context cache policy function.

Args
func A function that accepts a Key instance as argument and returns a bool indicating if it should be cached. May be None.

set_datastore_policy

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Set the context datastore policy function.

Args
func A function that accepts a Key instance as argument and returns a bool indicating if it should use the datastore. May be None.

set_memcache_policy

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Set the memcache policy function.

Args
func A function that accepts a Key instance as argument and returns a bool indicating if it should be cached. May be None.

set_memcache_timeout_policy

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Set the policy function for memcache timeout (expiration).

If the function returns 0, it implies the default timeout.

Args
func A function that accepts a key instance as argument and returns an integer indicating the desired memcache timeout. May be None.

transaction

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urlfetch

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