- Reference >
- Operators >
- Update Operators >
- Array Update Operators >
- $addToSet
$addToSet¶
-
$addToSet
¶ The
$addToSet
operator adds a value to an array only if the value is not in the array already. If the value is in the array,$addToSet
returns without modifying the array. Consider the following example:Here,
$addToSet
appends<addition>
to the array stored in<field>
that includes the element<value>
, only if<addition>
is not already a member of this array.
See also