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cursor.isExhausted()

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cursor.isExhausted()

Important

mongosh Method

This page documents a mongosh method. This is not the documentation for a language-specific driver, such as Node.js.

For MongoDB API drivers, refer to the language-specific MongoDB driver documentation.

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();
}
}
←  cursor.hint()cursor.itcount() →

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