MongoDB/PyMongo: upsert array element - mongodb

Question

I have the following document:
{'software_house': 'k1',
'client_id': '1234',
'transactions': [
{'antecedents': 12345,
'consequents': '015896018',
'antecedent support': 0.0030889166727954697},
{'antecedents': '932696735',
'consequents': '939605046',
'antecedent support': 0.0012502757961314996}
...
]}
In which key 'transactions' stores within an array 3 features, for each item.
I would like to update each item contained in the 'transactions' array, that matches with the same 'software_house', 'client_id', 'transactions.antecedents' and 'transactions.consequents'; and thus:
Overwriting the element within the array if it does exist
Appending a new value within 'transactions' if it doesn't
How could I achieve that using pymongo?

Answer 1

You can do this with an update with aggregation pipeline. You can first $filter the element matched. Then $setUnion with the item you want to upsert
PyMongo:
db.collection.update_many(filter = {
// the criteria you want to match outside array
"software_house": "k1",
"client_id": "1234"
},
update = [
{
"$addFields": {
"transactions": {
"$filter": {
"input": "$transactions",
"as": "t",
"cond": {
$not: {
$and: [
// the criteria you want to match in array
{
$eq: [
"$$t.antecedents",
12345
]
},
{
$eq: [
"$$t.consequents",
"015896018"
]
}
]
}
}
}
}
}
},
{
"$addFields": {
"transactions": {
"$setUnion": [
"$transactions",
[
{
"antecedents": 12345,
"consequents": "the entry you want to upsert",
"antecedent support": -1
}
]
]
}
}
}
])
Native MongoDB query:
db.collection.update({
// the criteria you want to match outside array
"software_house": "k1",
"client_id": "1234"
},
[
{
"$addFields": {
"transactions": {
"$filter": {
"input": "$transactions",
"as": "t",
"cond": {
$not: {
$and: [
// the criteria you want to match in array
{
$eq: [
"$$t.antecedents",
12345
]
},
{
$eq: [
"$$t.consequents",
"015896018"
]
}
]
}
}
}
}
}
},
{
"$addFields": {
"transactions": {
"$setUnion": [
"$transactions",
[
{
"antecedents": 12345,
"consequents": "the entry you want to upsert",
"antecedent support": -1
}
]
]
}
}
}
],
{
multi: true
})
Here is the Mongo playground for your reference.