Mongodb update duplicate array value - mongodb

Question

I am getting in an array of data and then want to insert that into my mongodb. I want to overwrite any duplicate values with the new one (on Im uploading) and if no duplicates just add it onto the current array.
I currently have:
db.cases.updateOne(
{ companyID: 218 },
{
$addToSet: {
cases: [AN ARRAY OF CASES]
},
$currentDate: { lastModified: true }
})
The collection has multiple companies and each has an array of cases - see image below :
The other thing that doesn't seem to work is that the currentDate doesn't seem to change whenever I update the cases, not sure if thats the way I have written the query?
Thank you.

Answer 1

You can use $addToSet (https://docs.mongodb.com/manual/reference/operator/update/addToSet/) with $[] (https://docs.mongodb.com/manual/reference/operator/update/positional-filtered/) to accomplish this.
I scripted an example in Node.js to show you what I mean:
const { MongoClient } = require('mongodb');
async function main() {
/**
* Connection URI. Update <username>, <password>, and <your-cluster-url> to reflect your cluster.
*/
const uri = "mongodb+srv://<username>:<password>#<your-cluster-url>?retryWrites=true&w=majority";
/**
* The Mongo Client you will use to interact with your database
*/
const client = new MongoClient(uri, { useUnifiedTopology: true });
try {
// Connect to the MongoDB cluster
await client.connect();
// Make the appropriate DB calls
await updateArray(client, 'id1')
} finally {
// Close the connection to the MongoDB cluster
await client.close();
}
}
main().catch(console.error);
async function updateArray(client, id) {
const docId = "299";
const mynewdoc = {
id: docId,
priority: 5,
casenumber: 40,
new: "field"
}
const result = await client.db("NameOfYourDb").collection("NameOfYourCollection").updateOne(
{ _id: id },
{
$set: {
"cases.$[element]": mynewdoc
}
},
{
arrayFilters: [{ "element.id": docId }]
}
)
if (result) {
console.log(result);
} else {
console.log(`Not found '${id}'`);
}
const result2 = await client.db("NameOfYourDb").collection("NameOfYourCollection").updateOne(
{ _id: id },
{
$addToSet: {
"cases": mynewdoc
}
}
)
if (result2) {
console.log(result2);
} else {
console.log(`Not found '${id}'`);
}
}
See https://www.mongodb.com/blog/post/quick-start-nodejs-mongodb--how-to-get-connected-to-your-database for an explanation of how the Node.js code is structured.

Answer 2

So I have figured a hack around but it is not exactly what I wanted - maybe someone can use this and expand upon it to make it work better:
db.cases.aggregate(
{ $match: { 'companyID': 218 }},
{ $unwind: '$cases' },
{ $group: { "_id": "$cases.casenumber", cases: {$push:'$cases'}, "count": { $sum:1 }}},
{ $match: { "count": { "$gt": 1 }}}
{ $project: { "cases": { $slice: [ "$cases", -1, { $subtract: [ { $size: "$cases" }, 1 ]}] }}},
{ $project: { "cases": { $arrayElemAt: ['$cases', 0] }}},
{ $group: { _id: 1, cases: {$push:'$cases' }}},
{ $out: 'cases' }
)
The only problem is that using out overwrites the cases document so I need to figure out a way to write it to the cases array inside of the company id (218)
Hopefully this can help someone though.
Thanks.