Unique Text
- To update the pipeline, you need to have MongoDB version 4.2 or higher
newProduct refers to the product that you wish to add (a JavaScript variable)- Check if the product already exists, and if not, add a field called "not-exist?"
- If it doesn't exist, add it to the end of the array
- If it does exist, find it in the array and update its quantity
- Remove the fields
newProduct and not-exists
*This approach requires two array reads. An alternative method could be using the $reduce function, but if you have numerous products, using $concatArrays within reduce can lead to slower performance. Thus, this solution is faster despite performing two array reads.
*To perform an update with a pipeline, you may need to check if Mongoose supports it. We are currently using MongoDB 5, so Java likely supports it. In case it's not supported, use the updateCommand command and execute it with runCommand(...).
You can test the code here
update({"_id" : "1"},
[{"$set":
{"newProduct":
{"product":"p1",
"options":{"size":"s1", "color":"c1"},
"quantity":1}}},
{"$set":
{"not-exists?":
{"$eq":
[{"$filter":
{"input":"$items",
"cond":
{"$and":
[{"$eq":["$$this.product", "$newProduct.product"]},
{"$eq":["$$this.options.size", "$newProduct.options.size"]},
{"$eq":["$$this.options.color", "$newProduct.options.color"]}]}}},
[]]}}},
{"$set":
{"items":
{"$cond":
["$not-exists?", {"$concatArrays":["$items", ["$newProduct"]]},
{"$map":
{"input":"$items",
"in":
{"$cond":
[{"$and":
[{"$eq":["$$this.product", "$newProduct.product"]},
{"$eq":["$$this.options.size", "$newProduct.options.size"]},
{"$eq":["$$this.options.color", "$newProduct.options.color"]}]},
{"$mergeObjects":
["$$this", {"quantity":{"$add":["$$this.quantity", 1]}}]},
"$$this"]}}}]}}},
{"$unset":["not-exists?", "newProduct"]}])
Unique Text 2
- If you prefer not to use the update pipeline, you can achieve the same result with multiple queries
Check if the item already exists:
db.collection.find({
"_id" : "1",
"items": {
"$elemMatch": {
"product": "p1",
"options": {
"size": "s1",
"color": "c1"
}
}
}
})
If the item does not exist:
db.collection.update({
"_id": "1"
},
{
"$push": {
"items": "NEWITEM" //Insert the new object here
}
})
If the item exists:
db.collection.update({"_id" : "1"},
{
"$inc": {
"items.$[i].quantity": 1
}
},
{
arrayFilters: [
{
"i.product": "p1",
"i.options.size": "s1",
"i.options.color": "c1"
}
]
})