$arrayElemAt (aggregation)
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Definition
-
$arrayElemAt
-
New in version 3.2.
Returns the element at the specified array index.
$arrayElemAt
has the following syntax:The
<array>
expression can be any valid expression as long as it resolves to an array.The
<idx>
expression can be any valid expression as long as it resolves to an integer.- If positive,
$arrayElemAt
returns the element at theidx
position, counting from the start of the array. - If negative,
$arrayElemAt
returns the element at theidx
position, counting from the end of the array.
If the
idx
exceeds the array bounds,$arrayElemAt
does not return any result.For more information on expressions, see Expressions.
- If positive,
Behavior
For more information on expressions, see Expressions.
Example | Results |
---|---|
{ $arrayElemAt: [ [ 1, 2, 3 ], 0 ] } |
1 |
{ $arrayElemAt: [ [ 1, 2, 3 ], -2 ] } |
2 |
{ $arrayElemAt: [ [ 1, 2, 3 ], 15 ] } |