# 9. API: Subscription Objects

Note

This object is an extension the DB API.

## 9.1. Subscription Methods

Subscription.registerquery(statement[, args])

  Registers the query for subsequent notification when tables referenced by the query are changed. This behaves similarly to `Cursor.execute()` but only queries are permitted and the `args` parameter must be a sequence or dictionary. If the `qos` parameter included the flag `oracledb.SUBSCR_QOS_QUERY` when the subscription was created, then the ID for the registered query is returned; otherwise, None is returned.

## 9.2. Subscription Attributes

Subscription.callback

  This read-only attribute returns the callback that was registered when the subscription was created.

Subscription.connection

  This read-only attribute returns the connection that was used to register the subscription when it was created.

Subscription.id

  This read-only attribute returns the value of `REGID` found in the database view `USER_CHANGE_NOTIFICATION_REGS` or the value of `REG_ID` found in the database view `USER_SUBSCR_REGISTRATIONS`. For AQ subscriptions, the value is 0.

Subscription.ip_address

  This read-only attribute returns the IP address used for callback notifications from the database server. If not set during construction, this value is None.

  For consistency and compliance with the PEP 8 naming style, the attribute ipAddress was renamed to ip_address. The old name will continue to work for a period of time.

Subscription.name

  This read-only attribute returns the name used to register the subscription when it was created.

Subscription.namespace

  This read-only attribute returns the namespace used to register the subscription when it was created.

Subscription.operations

  This read-only attribute returns the operations that will send notifications for each table or query that is registered using this subscription.

Subscription.port

  This read-only attribute returns the port used for callback notifications from the database server. If not set during construction, this value is zero.

Subscription.protocol

  This read-only attribute returns the protocol used to register the subscription when it was created.

Subscription.qos

  This read-only attribute returns the quality of service flags used to register the subscription when it was created.

Subscription.timeout

  This read-only attribute returns the timeout (in seconds) that was specified when the subscription was created. A value of 0 indicates that there is no timeout.

### 9.2.1. Message Objects

Note

This object is created internally when notification is received and passed to the callback procedure specified when a subscription is created.

Message.consumer_name

  This read-only attribute returns the name of the consumer which generated the notification. It will be populated if the subscription was created with the namespace `oracledb.SUBSCR_NAMESPACE_AQ` and the queue is a multiple consumer queue.

  For consistency and compliance with the PEP 8 naming style, the attribute consumerName was renamed to consumer_name. The old name will continue to work for a period of time.

Message.dbname

  This read-only attribute returns the name of the database that generated the notification.

Message.msgid

  This read-only attribute returns the message id of the AQ message which generated the notification. It will only be populated if the subscription was created with the namespace `oracledb.SUBSCR_NAMESPACE_AQ`.

Message.queries

  This read-only attribute returns a list of message query objects that give information about query result sets changed for this notification. This attribute will be None if the `qos` parameter did not include the flag `SUBSCR_QOS_QUERY` when the subscription was created.

Message.queue_name

  This read-only attribute returns the name of the queue which generated the notification. It will only be populated if the subscription was created with the namespace `oracledb.SUBSCR_NAMESPACE_AQ`.

  For consistency and compliance with the PEP 8 naming style, the attribute queueName was renamed to queue_name. The old name will continue to work for a period of time.

Message.registered

  This read-only attribute returns whether the subscription which generated this notification is still registered with the database. The subscription is automatically deregistered with the database when the subscription timeout value is reached or when the first notification is sent (when the quality of service flag `oracledb.SUBSCR_QOS_DEREG_NFY` is used).

Message.subscription

  This read-only attribute returns the subscription object for which this notification was generated.

Message.tables

  This read-only attribute returns a list of message table objects that give information about the tables changed for this notification. This attribute will be None if the `qos` parameter included the flag `SUBSCR_QOS_QUERY` when the subscription was created.

Message.txid

  This read-only attribute returns the id of the transaction that generated the notification.

Message.type

  This read-only attribute returns the type of message that has been sent. See the constants section on event types for additional information.

### 9.2.2. MessageTable Objects

Note

This object is created internally for each table changed when notification is received and is found in the tables attribute of message objects, and the tables attribute of message query objects.

MessageTable.name

  This read-only attribute returns the name of the table that was changed.

MessageTable.operation

  This read-only attribute returns the operation that took place on the table that was changed.

MessageTable.rows

  This read-only attribute returns a list of message row objects that give information about the rows changed on the table. This value is only filled in if the `qos` parameter to the `Connection.subscribe()` method included the flag `SUBSCR_QOS_ROWIDS`.

### 9.2.3. MessageRow Objects

Note

This object is created internally for each row changed on a table when notification is received and is found in the rows attribute of message table objects.

MessageRow.operation

  This read-only attribute returns the operation that took place on the row that was changed.

MessageRow.rowid

  This read-only attribute returns the rowid of the row that was changed.

### 9.2.4. MessageQuery Objects

Note

This object is created internally for each query result set changed when notification is received and is found in the queries attribute of message objects.

MessageQuery.id

  This read-only attribute returns the query id of the query for which the result set changed. The value will match the value returned by Subscription.registerquery when the related query was registered.

MessageQuery.operation

  This read-only attribute returns the operation that took place on the query result set that was changed. Valid values for this attribute are `EVENT_DEREG` and `EVENT_QUERYCHANGE`.

MessageQuery.tables

  This read-only attribute returns a list of message table objects that give information about the table changes that caused the query result set to change for this notification.