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- $push (aggregation)
$push (aggregation)¶
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$push
¶ Returns an array of all the values found in the selected field among the documents in that group. A value may appear more than once in the result set if more than one field in the grouped documents has that value.
Example¶
The following examples use the following collection named users
as
the input for the aggregation pipeline:
Push Values of a Single Field Into the Returned Array Field¶
To group by age
and return all the user
values for each age, use the
$push
operator.
For each age
, the operation returns the field users
that
contains an array of all the user
values associated with that age:
Push Documents Into the Returned Array Field¶
The $push
operator can return an array of documents.
To group by age
and return all the user
and associated
score
values for each age, use the $push
operator.
For each age
, the operation returns the field users
that
contains an array of documents. These documents contain the fields
userid
and score
that hold respectively the user
value and
the score
value associated with that age: