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Type:
New Feature
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Resolution: Done
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Priority:
Major - P3
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Affects Version/s: 2.1.1
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Component/s: Aggregation Framework
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None
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Minor Change
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Quint Iteration 4, Quint Iteration 5, Quint Iteration 6
Aggregation $project stage should support $slice operator on array fields similar to $slice in projection and syntax similar to aggregation $substr operator:
{ "$project" : { "newArray" : { "$slice" : [ "$oldarray" , 10, 4 ] } } }
The above would take 4 elements from oldarray starting at position 10 (akin to "skipping first ten elements, as position is 0 based).
Original description:
If I have a document with an array of values in it, I would like to be able to project a slice of those values while aggregating.
{ title: "A doc",
intervals: [
{ value: 1, foo: true, bar: false },
{ value: 2, foo: false, bar: true },
{ value: 3, foo: true, bar: false}
]
}
$project with a $slice should work as expected:
{ $project : {
title: 1,
fewerIntervals: {intervals:{$slice:2}}
}
}
results in a pipelined document =>
{ title: "A doc",
fewerIntervals: [
{ value: 1, foo: true, bar: false },
{ value: 2, foo: false, bar: true }
]
}
Similarly, the remainder of the existing $slice syntax should work as expected.
{ $project : {
title: 1,
fewerIntervals: {intervals:{$slice:[1,1]}}
}
}
should produce
{ title: "A doc",
fewerIntervals: [
{ value: 2, foo: false, bar: true }
]
}
- is duplicated by
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- Closed
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SERVER-15083 Allow projection of specific array elements by position
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- Closed
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- is related to
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DRIVERS-234 Aggregation Builder Support for 3.2
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- Closed
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- related to
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- Closed
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- Closed
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