Navigation

cursor.isExhausted()

On this page

  • Example
cursor.isExhausted()
Important
mongo Shell Method

This page documents the mongo shell method, and does not refer to the MongoDB Node.js driver (or any other driver) method. For corresponding MongoDB driver API, refer to your specific MongoDB driver documentation instead.

Returns:Boolean.

cursor.isExhausted() returns true if the cursor is closed and there are no remaining objects in the batch.

Use isExhausted() to support iterating cursors that remain open even if there are no documents remaining in the current batch, such as tailable or change stream cursors.

Consider the following while loop iterating through updates to a change stream cursor:

watchCursor = db.collection.watch();
while (watchCursor.hasNext()) {
watchCursor.next();
}

A change stream cursor can return an empty batch if no new data changes have occured within a set period of time. This causes the while loop to exit prematurely as cursor.hasNext() returns false when it detects the empty batch. However, the change stream cursor is still open and able to return more documents in the future.

Use cursor.isExhausted() to ensure the while loop only exits when the cursor is closed and there are no documents remaining in the batch:

watchCursor = db.collection.watch();
while (!watchCursor.isExhausted()) {
if (watchCursor.hasNext()){
watchCursor.next();
}
}
Give Feedback

On this page

  • Example