exclude find query fields while inserting document using upsert:true - mongodb

Question

db.getCollection('placeFollow').update(
{
"_id":ObjectId("5af19959204438676c0d5268"),
"count":{"$lt":2}
},
{
"$set":{"data":"check"}
},
{"upsert":true})
Error: E11000 duplicate key error collection: geoFame.placeFollow
index: id dup key: { : ObjectId('5af19959204438676c0d5268') }
Indexes
[
{
"v" : 2,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "geoFame.placeFollow"
}
]
I want to save the document if it doesn't exist. But above query is trying to insert _id, which is given in find query and it is throwing duplicate key error. How to exclude find query while inserting the document?

Answer 1

The core problem is of course supplying the _id, but you need to actually set the "count" field as well. Using $setOnInsert is probably what you want:
db.getCollection('placeFollow').update(
{ "count":{"$lt":2} },
{
"$set":{ "data": "check" },
"$setOnInsert": { "count": 2 }
},
{"upsert":true}
)
So you need to do something like that with whatever "default" or otherwise expected data should be in there. Otherwise MongoDB does not find a document because the field is not there and attempts inserting with the same _id value as provided.
Because your code is currently incorrect you need to remove the document which was created without the "count" first:
db.getCollection('placeFollow').deleteOne(
{ "_id":ObjectId("5af19959204438676c0d5268") }
)
Either that or set all documents with a default value of `count.
But basically you cannot use both an "primary key" and another condition when using "upsert", because if the document does not meet the condition then the upsert is attempted, and of course an existing value for _id is unique.