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Type:
Question
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Resolution: Works as Designed
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Priority:
Minor - P4
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None
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Affects Version/s: 3.4.3
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Component/s: Querying
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None
When running a query like that, we have an error "$in operator needs an array", even if the content of $oi expression is an array.
db.demo.aggregate(
[
{"$match":{"_id":{"$in":["aaa","bbb"]}}},
{"$project":{
"order_items":1,
"orders":1,
"oi":'$order_items.order_id'
}},
{
"$addFields":{"sz":{"$size":"$oi"}} // This works, $oi is an array and $size works on arrays
},
{"$match":{"orders.order_id": {"$in":"$oi"}} // This does not work even if $oi is an array
]
)
I guess this is complicated for query engine to be sure that $oi is an array, and $in operator has been strengthen considering the fact that value must be an array, but is there a way to achieve that ?