Trying to do a bulk upsert with Mongoose. What’s the cleanest way to do this?

(mongoose@4.9.1, mongodb@3.4.2)

TL;DR

await GasStation.collection.bulkWrite([ // <<==== use the model name
  {
    'updateOne': {
      'filter': { 'id': '<some id>' },
      'update': { '$set': { /* properties to update */ } },
      'upsert': true,  // <<==== upsert in every document
    }
  },
  /* other operations here... */
]);

Long story:

After struggling with Mongoose API poor documentation, I solved the bulk upsert tweaking updateOne:{} operation in the bulkWrite() method.

A couple of undocumented things to consider:

// suppose:
var GasStation = mongoose.model('gasstation', gasStationsSchema);
var bulkOps = [ ];

// for ( ... each gasStation to upsert ...) {
  let gasStation = { country:'a', localId:'b', xyz:'c' };
  // [populate gasStation as needed]
  // Each document should look like this: (note the 'upsert': true)
  let upsertDoc = {
    'updateOne': {
      'filter': { 'country': gasStation.country, 'localId': gasStation.localId },
      'update': gasStation,
      'upsert': true
  }};
  bulkOps.push(upsertDoc);
// end for loop

// now bulkWrite (note the use of 'Model.collection')
GasStation.collection.bulkWrite(bulkOps)
  .then( bulkWriteOpResult => {
    console.log('BULK update OK');
    console.log(JSON.stringify(bulkWriteOpResult, null, 2));
  })
  .catch( err => {
    console.log('BULK update error');
    console.log(JSON.stringify(err, null, 2));
  });

The two key things here are incomplete API documentation issues (at the time of writing, at least):

• 'upsert': true in each document. This is not documented in Mongoose API (), which often refers to node-mongodb-native driver. Looking at updateOne in this driver, you could think to add 'options':{'upsert': true}, but, no… that won’t do. I also tried to add both cases to the bulkWrite(,[options],) argument, with no effect either.
• GasStation.collection.bulkWrite(). Although Mongoose bulkWrite() method claims it should be called Model.bulkWrite() (in this case, GasStation.bulkWrite()), that will trigger MongoError: Unknown modifier: $__. So, Model.collection.bulkWrite() must be used.

Additionally, note:

• You don’t need to use the $set mongo operator in the updateOne.update field, since mongoose handles it in case of upsert (see bulkWrite() comments in example).
• Note that my unique index in the schema (needed for upsert to work properly) is defined as:

gasStationsSchema.index({ country: 1, localId: 1 }, { unique: true });

Hope it helps.

==> EDIT: (Mongoose 5?)

As noticed by @JustinSmith, the $set operator added by Mongoose doesn’t seem to be working anymore. Maybe it’s because of Mongoose 5?

In any case, using $set explicitly should do:

'update': { '$set': gasStation },