Fabrizio Ruggeri

Can you please report exactly the error? Which key in which collection is marked as duplicate?

Thank you @ozzyknox for the detailed report. I'll definetely look at this soon

Yes, thank you. I don't want to modify the array to an object. Not because is a bad solution but because I cannot release it without having a major release....

I'm discovering that mongo, when you specify an index on an array field, create an index for "each" value (https://docs.mongodb.com/manual/core/index-multikey/). This means that this solution never worked.

Version 5.0.0 should fix this issue. Please check

So, as specified on #7 this cannot be solved. `insertMany` doesn't call the necessary middlewres and so using several `create` is the way to go

I think you're right. I have to remember why I chose to use the 'pre' middleware. I'll be back to this, soon

Not really. Can you provide a little reproduction repo?

Hello @rernens. I have no time in these days to check this. I'll be back the next week. If there some code change you feel is necessary, you can make...

There was a PR about this but it didn't pass the tests and now it may be outdated. Have a look at the PR to see if you can use...