> For the complete MongoDB documentation index, see www.mongodb.com/docs/llms.txt

# MongoDB\ChangeStream::valid()

## Definition

Returns whether there is a current event in the change stream.

```php
function valid(): boolean
```

When manually iterating the change stream using [Iterator](https://php.net//manual/en/class.iterator.php) methods, this method should be used to determine if [`MongoDB\ChangeStream::current()`](https://www.mongodb.com/docs/php-library/current/reference/method/mongodbchangestream-current.md#mongodb-phpmethod-phpmethod.MongoDB-ChangeStream--current--) and [`MongoDB\ChangeStream::key()`](https://www.mongodb.com/docs/php-library/current/reference/method/mongodbchangestream-key.md#mongodb-phpmethod-phpmethod.MongoDB-ChangeStream--key--) can be called.

## Return Values

A boolean indicating whether there is a current event in the change stream.

## See Also

- [`MongoDB\Client::watch()`](https://www.mongodb.com/docs/php-library/current/reference/method/mongodbclient-watch.md#mongodb-phpmethod-phpmethod.MongoDB-Client--watch--)

- [`MongoDB\Collection::watch()`](https://www.mongodb.com/docs/php-library/current/reference/method/mongodbcollection-watch.md#mongodb-phpmethod-phpmethod.MongoDB-Collection--watch--)

- [`MongoDB\Database::watch()`](https://www.mongodb.com/docs/php-library/current/reference/method/mongodbdatabase-watch.md#mongodb-phpmethod-phpmethod.MongoDB-Database--watch--)

- [Iterator::valid()](https://php.net/iterator.valid)

- [Tailable Cursor Iteration](https://www.mongodb.com/docs/php-library/current/crud/query/cursor.md#std-label-php-tailable-cursor)

- [Change Streams](https://www.mongodb.com/docs/manual/changeStreams/) documentation in the MongoDB manual