Answers for "mongoose array update add"

append to array mongoose updateone

/*Another way to push items into array using Mongoose is-
  $addToSet, if you want only unique items to be pushed into 
  array. $push operator simply adds the object to array whether
  or not the object is already present, while $addToSet does that
  only if the object is not present in the array so as not to
  incorporate duplicacy.*/

PersonModel.update(
  { _id: person._id }, 
  { $addToSet: { friends: friend } }
);

mongoose update array in object

Person.findOneAndUpdate({_id: id}, 
{ 
  "$set": {[`items.$[outer].${propertyName}`]: value} 
},
{ 
  "arrayFilters": [{ "outer.id": itemId }]
},
function(err, response) {
  ...
})