Class Message (2.5.0)

Version 2.5.0

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Message(message, ack_id, delivery_attempt, request_queue)

A representation of a single Pub/Sub message.

The common way to interact with .pubsub_v1.subscriber.message.Message objects is to receive them in callbacks on subscriptions; most users should never have a need to instantiate them by hand. (The exception to this is if you are implementing a custom subclass to .pubsub_v1.subscriber._consumer.Consumer.)

Attributes

Name	Description
message_id	str The message ID. In general, you should not need to use this directly.
data	bytes The data in the message. Note that this will be a `bytes`, not a text string.
attributes	.ScalarMapContainer The attributes sent along with the message. See `attributes` for more information on this type.
publish_time	datetime The time that this message was originally published.

Inheritance

builtins.object > Message

Properties

ack_id

str: the ID used to ack the message.

attributes

Return the attributes of the underlying Pub/Sub Message.

Warning: A ScalarMapContainer behaves slightly differently than a dict. For a Pub / Sub message this is a string->string map. When trying to access a value via map['key'], if the key is not in the map, then the default value for the string type will be returned, which is an empty string. It may be more intuitive to just cast the map to a dict or to one use map.get.

Returns

Type	Description
.ScalarMapContainer	The message's attributes. This is a ``dict``-like object provided by ``google.protobuf``.

data

Return the data for the underlying Pub/Sub Message.

Returns

Type	Description
bytes	The message data. This is always a bytestring; if you want a text string, call `bytes.decode`.

delivery_attempt

The delivery attempt counter is 1 + (the sum of number of NACKs and number of ack_deadline exceeds) for this message. It is set to None if a DeadLetterPolicy is not set on the subscription.

A NACK is any call to ModifyAckDeadline with a 0 deadline. An ack_deadline exceeds event is whenever a message is not acknowledged within ack_deadline. Note that ack_deadline is initially Subscription.ackDeadlineSeconds, but may get extended automatically by the client library.

The first delivery of a given message will have this value as 1. The value is calculated at best effort and is approximate.

Returns

Type	Description
Optional[int]	The delivery attempt counter or None.

ordering_key

str: the ordering key used to publish the message.

publish_time

Return the time that the message was originally published.

Returns

Type	Description
datetime	The date and time that the message was published.

size

Return the size of the underlying message, in bytes.

Methods

Message

Message(message, ack_id, delivery_attempt, request_queue)

Construct the Message.

Note: This class should not be constructed directly; it is the responsibility of BasePolicy subclasses to do so.

Parameters

Name	Description
message	`.pubsub_v1.types.PubsubMessage` The message received from Pub/Sub. For performance reasons it should be the the raw protobuf message wrapped by the PubsubMessage class obtained through the message's .pb() method.
ack_id	str The ack_id received from Pub/Sub.
delivery_attempt	int The delivery attempt counter received from Pub/Sub if a DeadLetterPolicy is set on the subscription, and zero otherwise.
request_queue	queue.Queue A queue provided by the policy that can accept requests; the policy is responsible for handling those requests.

ack

ack()

Acknowledge the given message.

Acknowledging a message in Pub/Sub means that you are done with it, and it will not be delivered to this subscription again. You should avoid acknowledging messages until you have finished processing them, so that in the event of a failure, you receive the message again.

Warning: Acks in Pub/Sub are best effort. You should always ensure that your processing code is idempotent, as you may receive any given message more than once.

drop

drop()

Release the message from lease management.

This informs the policy to no longer hold on to the lease for this message. Pub/Sub will re-deliver the message if it is not acknowledged before the existing lease expires.

Warning: For most use cases, the only reason to drop a message from lease management is on ack or nack; this library automatically drop()s the message on ack or nack. You probably do not want to call this method directly.

modify_ack_deadline

modify_ack_deadline(seconds)

Resets the deadline for acknowledgement.

New deadline will be the given value of seconds from now.

The default implementation handles this for you; you should not need to manually deal with setting ack deadlines. The exception case is if you are implementing your own custom subclass of .pubsub_v1.subcriber._consumer.Consumer.

Parameter

Name	Description
seconds	int The number of seconds to set the lease deadline to. This should be between 0 and 600. Due to network latency, values below 10 are advised against.

nack

nack()

Decline to acknowldge the given message.

This will cause the message to be re-delivered to the subscription.