How to delete Duplicate objects inside array in multiple documents in mongodb? - mongodb

Question

I am trying to delete the duplicate object inside the array in multiple documents in Mongodb.
I try many ways but not able to fix
Document Structure:-
{
"_id" : ObjectId("5a544fe234602415114601d3"),
"GstDetails" : [
{
"_id" : ObjectId("5e4837374d62f4c95163908e"),
"StateId" : "1",
"GstIn" : "33ABFFM1655H1ZF",
"StateDesc" : "TAMIL NADU",
"CityDesc" : "CHENNAI"
},
{
"_id" : ObjectId("5e4837484d62f4c9516395e8"),
"StateId" : "1",
"GstIn" : "33ABFFM1655H1ZF",
"StateDesc" : "TAMIL NADU",
"CityDesc" : "CHENNAI"
}
]
}
Like that many more documents
I tried:-
db.Supplier.find({ "GstDetails": { $size: 2 } }).limit(1).forEach(function (doc) {
var stateId;
doc.GstDetails.forEach(function (data) {
if (data.StateId == stateId) {
pull doc.GstDetails[0];
} else {
stateId = data.StateId
}
print(JSON.stringify(doc));
});
db.Supplier.save(doc)
});

Answer 1

Check if aggregation below meets your requirements:
db.Supplier.aggregate([
{
$unwind: "$GstDetails"
},
{
$group: {
_id: {
_id: "$_id",
StateId: "$GstDetails.StateId"
},
GstDetails: {
$push: "$GstDetails"
}
}
},
{
$addFields: {
GstDetails: {
$slice: [
"$GstDetails",
1
]
}
}
},
{
$unwind: "$GstDetails"
},
{
$group: {
_id: "$_id._id",
GstDetails: {
$push: "$GstDetails"
}
}
}
])
MongoPlayground
Note: This read-only query. If it is OK, you need to add as last stage below operator (once you execute it, it will update your documents, no rollback available):
{$out: "Supplier"}