I have a document inside my Mongodb collection, something like this :
{
"a": "Bahrain",
"b": "Bahrain",
"c": "Bahrain",
"d": "Oman",
"e": "Oman",
"f": "Oman"
}
What I want is to get the keys corresponding to a value i.e query by the values.
Eg. For value Bahrain, I want to get {"a","b","c"} as the output.
You'll need to transform the $$ROOT variable to an array. then filter it according to the condition you want, like so:
db.collection.aggregate([
{
$match: { _id: docId }
},
{
$project: {
fieldKeys: {
$map: {
input: {
$filter: {
input: {
"$objectToArray": "$$ROOT"
},
as: "datum",
cond: {
$eq: [
"$$datum.v",
"Bahrain"
]
}
}
},
as: "key",
in: "$$key.k"
}
}
}
}
])