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Type:
Bug
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Resolution: Done
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Priority:
Major - P3
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Affects Version/s: None
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Component/s: Aggregation Framework
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None
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Fully Compatible
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ALL
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v3.4
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Query 2017-05-29
db.a.find()
{ "_id" : ObjectId("58ebbf82016ce019673b111c"), "a" : [ { "_id" : 1 }, { "_id" : 2 } ] }
{ "_id" : ObjectId("58ebbf8d016ce019673b111d"), "a" : [ { "_id" : 5 }, { "_id" : 12 } ] }
> db.b.find()
{ "_id" : 1 }
{ "_id" : 2 }
{ "_id" : 3 }
{ "_id" : 5 }
{ "_id" : 12 }
I would expect $lookup using "a._id" as localField to work since SERVER-22881 was fixed, however:
db.a.aggregate({$lookup:{from:"b", localField:"a._id", foreignField:"_id", as:"details"}})
{ "_id" : ObjectId("58ebbf82016ce019673b111c"), "a" : [ { "_id" : 1 }, { "_id" : 2 } ], "details" : [ ] }
{ "_id" : ObjectId("58ebbf8d016ce019673b111d"), "a" : [ { "_id" : 5 }, { "_id" : 12 } ], "details" : [ ] }
"details" is properly populated only if I unwind "a" and use "a._id" or if I create another field first in $addFields or $project from "$a._id" (which makes it a simple array) then it works as localField:
db.a.aggregate({$addFields:{a:"$a._id"}},{$lookup:{from:"b", localField:"a", foreignField:"_id", as:"details"}})
{ "_id" : ObjectId("58ebbf82016ce019673b111c"), "a" : [ 1, 2 ], "details" : [ { "_id" : 1 }, { "_id" : 2 } ] }
{ "_id" : ObjectId("58ebbf8d016ce019673b111d"), "a" : [ 5, 12 ], "details" : [ { "_id" : 5 }, { "_id" : 12 } ] }
- is duplicated by
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- Closed
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- is related to
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SERVER-42306 $lookup with an array of sub objects should allow for an option to allow each sub object to find join partners
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- Backlog
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