Database Manual / Reference / Query Language

Update Operators

The following modifiers are available for use in update operations such as db.collection.updateMany() and db.collection.findAndModify().

Compatibility

You can use update operators for deployments hosted in the following environments:

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

Syntax

Specify update operators in the following form:

{
   <operator1>: { <field1>: <value1>, ... },
   <operator2>: { <field2>: <value2>, ... },
   ...
}

Update Operators

Behavior

Starting in MongoDB 5.0, update operators process document fields with string-based names in lexicographic order. Fields with numeric names are processed in numeric order.

Consider this example $set command:

{ $set: { "a.2": <new value>, "a.10": <new value>, } }

In MongoDB 5.0 and later, "a.2" is processed before "a.10" because 2 comes before 10 in numeric order.

Fields

NameDescription

$currentDate

Sets the value of a field to current date, either as a Date or a Timestamp.

$inc

Increments the value of the field by the specified amount.

$min

Only updates the field if the specified value is less than the existing field value.

$max

Only updates the field if the specified value is greater than the existing field value.

$mul

Multiplies the value of the field by the specified amount.

$rename

Renames a field.

$set

Sets the value of a field in a document.

$setOnInsert

Sets the value of a field if an update results in an insert of a document. Has no effect on update operations that modify existing documents.

$unset

Removes the specified field from a document.

Array

Operators

NameDescription

$

Acts as a placeholder to update the first element that matches the query condition.

$[]

Acts as a placeholder to update all elements in an array for the documents that match the query condition.

$[<identifier>]

Acts as a placeholder to update all elements that match the arrayFilters condition for the documents that match the query condition.

$addToSet

Adds elements to an array only if they do not already exist in the set.

$pop

Removes the first or last item of an array.

$pull

Removes all array elements that match a specified query.

$push

Adds an item to an array.

$pullAll

Removes all matching values from an array.

Modifiers

NameDescription

$each

Modifies the $push and $addToSet operators to append multiple items for array updates.

$position

Modifies the $push operator to specify the position in the array to add elements.

$slice

Modifies the $push operator to limit the size of updated arrays.

$sort

Modifies the $push operator to reorder documents stored in an array.

Bitwise

NameDescription

$bit

Performs bitwise AND, OR, and XOR updates of integer values.

Updates with Aggregation Pipeline

To create expressive update statements, such as conditional updates based on current field values or single-field updates that use the value of another field, you can perform updates with an aggregation pipeline.

For syntax and examples, see Updates with Aggregation Pipeline.