MongoDB Update Operators and Array Patterns

MongoDB•Permalink

Use $set, $unset, $inc, $push, $addToSet, positional updates, and arrayFilters for real-world MongoDB mutations.

View

Standard Detailed Compact

Export

Copy the compact sheet, download it, or print it.

Download

`D` dense toggle · `C` copy all

Field update operators

Common document mutation operators.

Increment a numeric field

Increase a counter with `$inc`.

↗#

javascriptANYmongodbincupdate

javascript

db.posts.updateOne({ _id: 1 }, { $inc: { views: 1 } })

Ideal for counters, sequence-like values, and metrics.

Remove a field

Delete one or more fields from matched documents.

↗#

javascriptANYmongodbunsetupdate

javascript

db.users.updateMany({ legacy_flag: { $exists: true } }, { $unset: { legacy_flag: "" } })

`$unset` removes the field from documents instead of setting it to null.

Rename a field

Change a field name in-place.

↗#

javascriptANYmongodbrenameschema

javascript

db.users.updateMany({}, { $rename: { fullname: "full_name" } })

Useful during schema evolution.

Stamp an update time

Set a field to the current date.

↗#

javascriptANYmongodbcurrentDatetimestamps

javascript

db.users.updateOne({ _id: 1 }, { $currentDate: { updated_at: true } })

A simple way to maintain mutation timestamps from the database side.

Arrays and positional updates

Append, deduplicate, and target nested array elements.

Append to an array

Push one item onto an array field.

↗#

javascriptANYmongodbpusharrays

javascript

db.users.updateOne({ _id: 1 }, { $push: { tags: "beta" } })

`$push` appends a value even if it already exists.

Append only if missing

Use `$addToSet` to avoid duplicates.

↗#

javascriptANYmongodbaddToSetarrays

javascript

db.users.updateOne({ _id: 1 }, { $addToSet: { tags: "beta" } })

Great for tag or role arrays where uniqueness matters.

Remove array values

Delete matching values from an array.

↗#

javascriptANYmongodbpullarrays

javascript

db.users.updateOne({ _id: 1 }, { $pull: { tags: "beta" } })

Useful for cleanup and preference toggles.

Update the first matching array element

Use the positional `$` operator.

↗#

javascriptANYmongodbarrayspositional

javascript

db.orders.updateOne({ _id: 1, "items.sku": "A100" }, { $set: { "items.$.qty": 3 } })

The positional operator targets the first matched array element in the query.

Target specific nested elements with arrayFilters

Update matching array elements with named filters.

↗#

javascriptANYmongodbarraysarrayFilters

javascript

db.orders.updateOne(
  { _id: 1 },
  { $set: { "items.$[line].discounted": true } },
  { arrayFilters: [{ "line.qty": { $gte: 5 } }] }
)

`arrayFilters` are powerful for targeted nested updates without rewriting the whole array.

More in MongoDB

MongoDB Transactions and Change Streams

Use sessions, multi-document transactions, and change streams for modern event-driven and consistency-sensitive MongoDB applications.

MongoDB Backup, Restore, and Replica Set Workflows

Use mongodump, mongorestore, replica set commands, and diagnostic tools for operational MongoDB workflows.

MongoDB Import, Export, and Database Tools

Use mongoimport, mongoexport, bsondump, and GridFS tools for practical MongoDB data movement workflows.

MongoDB Users, Roles, and Administrative Commands

Create users, grant roles, inspect server status, and run the most common administrative commands in MongoDB.

MongoDB Indexes, Explain Plans, and Performance

Create indexes, inspect query plans, and troubleshoot common MongoDB query performance issues.

MongoDB Aggregation Pipeline Patterns

Group, project, sort, unwind, lookup, facet, and aggregate analytics data with MongoDB pipelines.

Recommended next

No recommendations yet.

Browse all sheets →