cursor.map()¶

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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 :driver:`MongoDB driver documentation </>`.

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

:v4.4:`mongo shell v4.4 </mongo>`
mongo shell v4.2

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.

Behavior¶

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().

Examples¶

These examples refer to the products collection:

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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 }
])

Return a Value From a Collection¶

Get the product names.

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

Return Results as an `Array`¶

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

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

Confirm that the output is an Array

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salePrices.constructor.name

cursor.map()¶

Behavior¶

Examples¶

Return a Value From a Collection¶

Return Results as an Array¶

Return Results as an `Array`¶