MongoDB count() method

MongoDB count is accustomed to counting the nunber of a document from collections. We have tracked down the number of documents using the count method in MongoDB. We have used the find method to display all the documents of a collection. But, if we need to know the actual count of the documents, then we should use the count method.

MongoDB count() method returns the number of results in a specified collection or number of documents that match in a find() query. We cannot use this method in transactions.

Syntax of count()

db.collection.count(query, options)

Here, the count() returns only number of results that match a query. The parameter 'query' is the selection criteria, The type of this argument is a document. The second parameter is an optional, like - limit, skip, hint and are optional.

Optional parameters with count query in MongoDB:

Parameter	Description
count	Count the collection or view documents
query	The query selection criteria.
limit	The maximum number of documents to count.
skip	The number of documents to skip before counting.
hint	An index name hint(specification) for the query.
readConcern	The default read concern level of MongoDB is local.
collation	It specifies the collation to use for the operation.

Example: Count all documents from a collection

The following statement returns total number of students in a collection.

db.students.count();

Example: Count documents that match a query

In the given example, we have counted the documents that match query from 'students' table using count method in MongoDB.

db.runCommand({count:'students', query: {"age":11}})

MongoDB count() with find()

We can use the count() method with find() query. The given statement returns total number of students of class '5C'.

db.students.find({"class": "5C"}).count();