MongoDB: db.collection.update() method

Last update on August 19 2022 21:50:43 (UTC/GMT +8 hours)

db.collection.update

The db.collection.update() method is used to modify an existing document or documents in a collection. The method can modify specific fields of an existing document or documents or replace an existing document entirely, depending on the update parameter. By default, the update() method updates a single document. Set the Multi-Parameter to update all documents that match the query criteria.

Syntax:

db.collection.update(query, update, options)

Parameters:

Name	Description	Required / Optional	Type
query	The selection criteria for the update. The same query selectors as in the find() method are available.	Required	document
update	The modifications to apply.	Required	document
upsert	If set to true, creates a new document when no document matches the query criteria. The default value is false, which does not insert a new document when no match is found.	Optional	boolean
multi	If set to true, updates multiple documents that meet the query criteria. If set to false, updates one document. The default value is false.	Optional	boolean
writeConcern	A document expressing the write concern. Omit to use the default write concern.	Optional	document

Example: MongoDB: db.collection.update() method

Sample document in the restaurants collection:


{
  "address": {
     "building": "1007",
     "coord": [ -73.856077, 40.848447 ],
     "street": "Morris Park Ave",
     "zipcode": "10462"
  },
  "borough": "Bronx",
  "cuisine": "Bakery",
  "grades": [
     { "date": { "$date": 1393804800000 }, "grade": "A", "score": 2 },
     { "date": { "$date": 1378857600000 }, "grade": "A", "score": 6 },
     { "date": { "$date": 1358985600000 }, "grade": "A", "score": 10 },
     { "date": { "$date": 1322006400000 }, "grade": "A", "score": 9 },
     { "date": { "$date": 1299715200000 }, "grade": "B", "score": 14 }
  ],
  "name": "Morris Park Bake Shop",
  "restaurant_id": "30075445"
}

Retrieve the restaurants data from here

Behavior

Safe Writes

The update() method uses the update command, which uses the default write concern. To specify a different write concern, include the writeConcern option in the options parameter.

Update Parameter

The update() method either modifies specific fields in existing documents or replaces an existing document entirely.

Update Specific Fields

If the <update> document contains update operator modifiers, such as those using the $set modifier, then:

The <update> document must contain only update operator expressions.
The update() method updates only the corresponding fields in the document.

To update an embedded document or an array as a whole, specify the replacement value for the field. To update particular fields in an embedded document or in an array, use dot notation to specify the field.

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