Seems that (at least with MySQL 5.7.23) if you do not set an _id field in the array of items to "add", it fails with error...
[HY000] Document is missing a required field
Adding "_id" => xxxx does resolve the issue.
Seems that (at least with MySQL 5.7.23) if you do not set an _id field in the array of items to "add", it fails with error...
[HY000] Document is missing a required field
Adding "_id" => xxxx does resolve the issue.