I've got a document in MongoDB which has a multi-dimensional array as shown below.
{"_id":1,
"name":"Johnson",
"card":[
["",12,25,"","",52,60,"",86],
[1,17,29,"",43,"","","",89],
[3,"","",34,45,"",62,70,""]
]
}
I'm looking for a query that returns the index of a particular element in the array, for example, say 29 whose index is [1][2] but when i queried as:
> db.test.aggregate([{$project:{index:{$indexOfArray:["$card",29]}}}])
i got the result as:
{ "_id" : 1, "index" : -1 }
which is not true. I found that this query method works only for one-dimensional array and I'm unable to figure out how to find the index of multi-dimensional array in MongoDB. Any help will be appreciated. Thankyou
Not exactly clear on what datatype [1][2] is, so rendering the desired output is a bit of a challenge. Here is a attempt to help your question...
Test Data
db.collection.insert(
{
"name":"Johnson",
"card":[
["", 12, 25, "", "", 52, 60, "", 86],
[1, 17, 29, "", 43, "", "", "", 89],
[3, "", "", 34, 45, "", 62, 70, ""]
]
}
(Assumes a hard-coded value of 29 to search for)
Aggregate
EDIT 2021-12-09 - ADDED $project TO CAST RESULTS AS INTEGER. WAS NumberLong()
db.collection.aggregate([
{
$unwind:
{
path: "$card",
includeArrayIndex: "outerIndex"
}
},
{
$unwind:
{
path: "$card",
includeArrayIndex: "innerIndex"
}
},
{
$match:
{
"card": 29
}
},
{
$project:
{
name: 1,
card: 1,
outerIndex: { $convert: { input: "$outerIndex", to: "int" } },
innerIndex: { $convert: { input: "$innerIndex", to: "int" } }
}
}
])
Results
[
{
_id: ObjectId("61b13476c6c466d7d1ea9b5e"),
name: 'Johnson',
card: 29,
outerIndex: 1,
innerIndex: 2
}
]
Unwanted fields can be supressed with another $project stage, but I did not include it here since I was not clear on desired output.