I have such a schema:
doc:
{
//Some fields
visits:
[
{
userID: Int32
time: Int64
}
]
}
I want to first check if a specific userID
exists, if not, push a document with that userID
and system time
, else just update time
value. I know neither $push
nor $addToSet
are not able to do that. Also using $
with upsert:true
doesn't work, because of official documentation advice which says DB will use $
as field name instead of operator when trying to upsert.
Please guide me about this. Thanks
You can use the updateOne() or updateMany() methods to add, update, or remove array elements based on the specified criteria. It is recommended to use the updateMany() method to update multiple arrays in a collection.
In MongoDB, the $push operator is used to appends a specified value to an array. If the mentioned field is absent in the document to update, the $push operator add it as a new field and includes mentioned value as its element. If the updating field is not an array type field the operation failed.
Update Nested Arrays in Conjunction with $[]The $[<identifier>] filtered positional operator, in conjunction with the $[] all positional operator, can be used to update nested arrays. The following updates the values that are greater than or equal to 8 in the nested grades.
You can use $addToSet
to add an item to the array and $set
to update an existing item in this array.
The following will add a new item to the array if the userID
is not found in the array :
db.doc.update({
visits: {
"$not": {
"$elemMatch": {
"userID": 4
}
}
}
}, {
$addToSet: {
visits: {
"userID": 4,
"time": 1482607614
}
}
}, { multi: true });
The following will update the subdocument array item if it matches the userId
:
db.doc.update({ "visits.userID": 2 }, {
$set: {
"visits.$.time": 1482607614
}
}, { multi: true });
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With