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MongoDB\\ChangeStream::key()
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.. default-domain:: mongodb
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Definition
----------
.. phpmethod:: MongoDB\\ChangeStream::key()
Returns the index of the current event in the change stream.
.. code-block:: php
function key(): integer|null
The index of the first event in a change stream starts at zero and will
increment by one for each subsequent event.
Return Values
-------------
The index of the current event in the change stream, or ``null`` if there is no
current event (i.e. :phpmethod:`MongoDB\\ChangeStream::valid()` returns
``false``).
Examples
--------
This example reports the index of events while iterating a change stream.
.. code-block:: php
<?php
$uri = 'mongodb://rs1.example.com,rs2.example.com/?replicaSet=myReplicaSet';
$collection = (new MongoDB\Client($uri))->test->inventory;
$changeStream = $collection->watch();
for ($changeStream->rewind(); true; $changeStream->next()) {
if ( ! $changeStream->valid()) {
continue;
}
$event = $changeStream->current();
printf("%d: %s\n", $changeStream->key(), $event['operationType']);
}
Assuming that a document was inserted, updated, and deleted while the above
script was iterating the change stream, the output would then resemble:
.. code-block:: none
0: insert
1: update
2: delete
See Also
--------
- :phpmethod:`MongoDB\\Client::watch()`
- :phpmethod:`MongoDB\\Collection::watch()`
- :phpmethod:`MongoDB\\Database::watch()`
- :php:`Iterator::key() <iterator.key>`
- :ref:`Tailable Cursor Iteration <php-tailable-cursor>`
- :manual:`Change Streams </changeStreams>` documentation in the MongoDB manual
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