$each
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Definition
$each
The
$each
modifier is available for use with the$addToSet
operator and the$push
operator.Use with the
$addToSet
operator to add multiple values to an array<field>
if the values do not exist in the<field>
.{ $addToSet: { <field>: { $each: [ <value1>, <value2> ... ] } } } Use with the
$push
operator to append multiple values to an array<field>
.{ $push: { <field>: { $each: [ <value1>, <value2> ... ] } } } The
$push
operator can use$each
modifier with other modifiers. For a list of modifiers available for$push
, see Modifiers.
Behavior
In MongoDB 4.4 and earlier, update operators process document fields in lexicographic order. See Update Operators Behavior for details.
Examples
Use $each
with $push
Operator
The following example appends each element of [ 90, 92, 85 ]
to
the scores
array for the document where the name
field
equals joe
:
db.students.update( { name: "joe" }, { $push: { scores: { $each: [ 90, 92, 85 ] } } } )
Use $each
with $addToSet
Operator
A collection inventory
has the following document:
{ _id: 2, item: "cable", tags: [ "electronics", "supplies" ] }
Then the following operation uses the $addToSet
operator
with the $each
modifier to add multiple elements to the
tags
array:
db.inventory.update( { _id: 2 }, { $addToSet: { tags: { $each: [ "camera", "electronics", "accessories" ] } } } )
The operation adds only "camera"
and "accessories"
to the
tags
array since "electronics"
already exists in the array:
{ _id: 2, item: "cable", tags: [ "electronics", "supplies", "camera", "accessories" ] }