cursor.map() (original) (raw)

cursor.map(function)

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-specificMongoDB driver documentation.

Applies a function to each document visited by the cursor and collects the return values from successive applications of thefunction into a Cursor object.

The cursor.map() method has the following parameter:

Parameter	Type	Description
function	function	A function to apply to each document visited by the cursor.

This method is available in deployments hosted in the following environments:

MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

Note

This command is supported in all MongoDB Atlas clusters. For information on Atlas support for all commands, seeUnsupported Commands.

MongoDB Enterprise: The subscription-based, self-managed version of MongoDB
MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB

cursor.map() returns a Cursor object. Note that.map() only converts the type, it does not create a new cursor. You can convert the Cursor object to an Array with .toArray().

These examples refer to the products collection:


db.products.insertMany([

   { _id: 1, name: 'widget', price: 10.89 },

   { _id: 2, name: 'thing', price: 11.24 },

   { _id: 3, name: 'moppet', price: 8 },

   { _id: 4, name: 'cosa', price: 24.19 }

])

Get the product names.


db.products.find().map( function(p) { return p.name; } ) ;

Calculate a discounted sale price and return the results as an array.


var salePrices = db.products.find().map( function(p) { return p.price * .9 } ).toArray() ;

Confirm that the output is an Array


salePrices.constructor.name