如何使用 NodeJS 合并到 MongoDB 中现有的唯一 ID？

Question

I want to sum a documents field when I insert a new entry that has a duplicate unique id. This is what I have so far:

 MongoClient.connect(process.env.MONGODB_URI || process.env.DB_CONNECTION, { useUnifiedTopology: true, useNewUrlParser: true }, function (err, db) { if (err) throw err; const dbo = db.db("mydb"); const messageTable = dbo.collection("comments"); for(var key in words){ let myobj = [{ _id: key, frequency: words[key] }]; messageTable.insertMany(myobj, function(err, res){ if (err) throw err; console.log("documents inserted"); }); messageTable.aggregate([ { $match: { _id: key } }, { $group: { _id: key, total: { $sum: "$frequency" } } }, { $merge: { into: "comments", whenMatched: "replace" } } ]); } })

From reading the docs I tried to use the aggregate method to merge new entries if the key already exists as a unique id. This is not currently working. How would I merge duplicate documents in my MongoDB using NodeJS?

Answer 1

I have figured out a way to do this by reading the docs and with the help of a reddit user. If anyone wants to do something similar this is the easiest method:

 messageTable.findOneAndUpdate({ "_id": key },{$set: { "_id": key}, $inc: { "frequency": words[key] }},{upsert: true}).then( console.log("document updated or inserted") )

With this method the first argument is your query, the second changes the first match which in my case increments the frequency field, and the third are options for the method. The upsert option has a default value of false but when true creates a new document if one does not already exist. If you wish to read more you can find info here