mongoose append to object code example

Example 1: how to append data to a field in mongoose model

exports.addFriend = function (req, res, next)
{
var friend = {"firstName": req.body.fName, "lastName": req.body.lName};
Users.findOneAndUpdate({name: req.user.name}, {$push: {friends: friend}});
};

Example 2: add in to array mongoose

// With { $push: { field: element } }

// Example:
const elementToPush = { a: 1, b: 2 };
const body = { $push: { arrayField: elementToPush } };
model.patch(id, body);