Docs Menu

cursor.map()

On this page

  • Behavior
  • Examples
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-specific MongoDB driver documentation.

For the legacy mongo shell documentation, refer to the documentation for the corresponding MongoDB Server release:

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

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
Tip
See also:

cursor.forEach() for similar functionality.

←  cursor.limit()cursor.max() →

On this page

Give Feedback
© 2022 MongoDB, Inc.

About

  • Careers
  • Investor Relations
  • Legal Notices
  • Privacy Notices
  • Security Information
  • Trust Center
© 2022 MongoDB, Inc.