$lookup defined array variables

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    • Type: Bug
    • Resolution: Works as Designed
    • Priority: Major - P3
    • None
    • Affects Version/s: 3.6.0, 3.6.4
    • Component/s: Aggregation Framework
    • None
    • ALL
    • Hide 
      db.test.insert({ foo: [1, 2] })
db.test.insert({ bar: 1 })

      db.test.aggregate([
    {
        $match: {
            foo: 1
        }
    },
    {
        $lookup: {
            from: 'test',
            let: {
                arr: '$foo'
            },
            pipeline: [
                {
                    $match: {
                        bar: {
                            $in: '$$arr'
                        }
                    }
                }
            ],
            as: 'result'
        }
    }
])

      and it will throw:

      { 
    "operationTime" : Timestamp(1526389658, 1), 
    "ok" : 0.0, 
    "errmsg" : "$in needs an array", 
    "code" : NumberInt(2), 
    "codeName" : "BadValue", 
    "$clusterTime" : {
        "clusterTime" : Timestamp(1526389658, 1), 
        "signature" : {
            "hash" : BinData(0, "AAAAAAAAAAAAAAAAAAAAAAAAAAA="), 
            "keyId" : NumberLong(0)
        }
    }
}

      but projection shows:

      db.test.aggregate([
    {
        $match: {
            foo: 1
        }
    },
    {
        $lookup: {
            from: 'test',
            let: {
                arr: '$foo'
            },
            pipeline: [
                {
                    $match: {
                        bar:1
                    }
                },
                {
                    $project: {
                        arr: '$$arr'
                    }
                }
            ],
            as: 'result'
        }
    }
])

      that $$arr is in fact an array:

      { 
    "_id" : ObjectId("5afad86a91c788853024d506"), 
    "foo" : [
        1.0, 
        2.0
    ], 
    "result" : [
        {
            "_id" : ObjectId("5afadc2c91c788853024d507"), 
            "arr" : [
                1.0, 
                2.0
            ]
        }
    ]
}
      Show
      db.test.insert({ foo: [1, 2] }) db.test.insert({ bar: 1 }) db.test.aggregate([ { $match: { foo: 1 } }, { $lookup: { from: 'test' , let: { arr: '$foo' }, pipeline: [ { $match: { bar: { $in: '$$arr' } } } ], as: 'result' } } ]) and it will throw: { "operationTime" : Timestamp(1526389658, 1), "ok" : 0.0, "errmsg" : "$in needs an array" , "code" : NumberInt(2), "codeName" : "BadValue" , "$clusterTime" : { "clusterTime" : Timestamp(1526389658, 1), "signature" : { "hash" : BinData(0, "AAAAAAAAAAAAAAAAAAAAAAAAAAA=" ), "keyId" : NumberLong(0) } } } but projection shows: db.test.aggregate([ { $match: { foo: 1 } }, { $lookup: { from: 'test' , let: { arr: '$foo' }, pipeline: [ { $match: { bar:1 } }, { $project: { arr: '$$arr' } } ], as: 'result' } } ]) that $$arr is in fact an array: { "_id" : ObjectId( "5afad86a91c788853024d506" ), "foo" : [ 1.0, 2.0 ], "result" : [ { "_id" : ObjectId( "5afadc2c91c788853024d507" ), "arr" : [ 1.0, 2.0 ] } ] }
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      It seems that array expression operators they do not see the defined variables as arrays.

            Assignee:
            Unassigned
            Reporter:
            NOVALUE Filip
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            Watchers:
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              Created:
              Updated:
              Resolved: