count() - Find the number of documents command

query

This optional parameter specifies a filter for selecting a subset of documents and returns a count.

Example 1: Get the number of documents in the books collection:

db.books.count()

Sample output is as follows:

15

Example 2: Get the number of documents for an author:

db.books.count({author: "Tolkien, J.R"})

Sample output is as follows:

2