[SERVER-20163] aggregation: Should have a $zip operator to combine arrays - MongoDB Jira

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    $zip: {

        inputs: <array of expressions>

        defaults: <array of expressions>

        useLongestLength: <bool - default false, cannot specify defaults if false>

{_id: 0, evens: [0, 2, 4, 6], odds: [1, 3, 5]}

{_id: 1, evens: [4], odds: [1, 3]}

db.coll.aggregate([{

    $project: {

        z: {

            $zip: {

                inputs: ["$evens", "$odds"],

                defaults: [0, 1],

                useLongestLength: true

}])

{_id: 0, z: [[0, 1], [2, 3], [4, 5], [6, 1]]}

{_id: 1, z: [[4, 1], [0, 3]]}

Uses length of shortest array, unless useLongestLength is true. If useLongestLength is true, but defaults is not specified, will use null to fill in.
The use of null here is consistent with our parsing of array literals (e.g. [0, "$field"] will become [0, null] if 'field' does not exist).
'defaults' cannot be specified unless useLongestLength is true.
If any input is null, will return null. $map returns null if its input is nullish.
Will error if any input is not an array (and is not nullish).
Will error if 'defaults' is specified without 'useLongestLength', or is not the same length as 'inputs'.

is depended on by

CSHARP-1620 aggregation: Should have a $zip operator to combine arrays

is documented by

DOCS-8821 3.4 agg operator $zip

is duplicated by

SERVER-17960 allow parallel $map processing for multiple arrays

related to

DRIVERS-297 Aggregation Framework Support for 3.4