Avoid push/addToSet null value to mongodb array

Question

When using $push or $addToSet operator in mongoose, and the value I give (friend.id) is null or undefined, it will push a null element to the array.

dbUser.findByIdAndUpdate(
 _id,
 {
  $addToSet: {
  'friendsBlackList': friendB.id ,
  'FriendsWhiteList': friendW.id ,
  },
  },
  { new: true, upsert: true }
});

How to avoid pushing a null element? Can it be controlled in the mongoose schema? Thank you for your suggestions.

Answer 1

I'm not familiar with Mongoose and its syntax, but what your describing can be done with the following pseudocode:

var update = { $addToSet:{}};
if(friendB.id !=null){
    update.$addToSet.friendsBlackList = friendB.id
}
if(friendW.id !=null){
    update.$addToSet.friendsWhiteList = friendW.id
}

dbUser.findByIdAndUpdate(_id,update,{ new: true, upsert: true });

Some drivers (ie Morphia) have options you can set to ignore null and empty values. You should check if Mongoose has such options as well.