$unset
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Definition
Note
$unset
The
$unset
operator deletes a particular field. Consider the following syntax:{ $unset: { <field1>: "", ... } } The specified value in the
$unset
expression (i.e.""
) does not impact the operation.To specify a
<field>
in an embedded document or in an array, use dot notation.
Behavior
In MongoDB 4.4 and earlier, update operators process document fields in lexicographic order. See Update Operators Behavior for details.
If the field does not exist, then $unset
does nothing (i.e.
no operation).
When used with $
to match an array element, $unset
replaces the matching element with null
rather than removing the
matching element from the array. This behavior keeps consistent the
array size and element positions.
Example
The following update()
operation uses the
$unset
operator to remove the fields quantity
and
instock
from the first document in the products
collection
where the field sku
has a value of unknown
.
db.products.update( { sku: "unknown" }, { $unset: { quantity: "", instock: "" } } )