Database
[{"_id":ObjectId("5a934e000102030405000000"),"employee":[{"_id":"5fc3ae2c694e3a11291c9f05","workplace":"5fc2c6e58f4fb3520ecb45ce","workAs":"ant-work-as"}]}]
Query
db.collection.update({_id:ObjectId("5a934e000102030405000000")},{$push:{employee:{"_id":"5fc3ae2c694e3a11291c9f06","workplace":"5fc2c6e58f4fb3520ecb45ce","workAs":"ant-work-as-2"}}})