Push items into mongo array via mongoose

Basically I have a mongodb collection called ‘people’
whose schema is as follows:

people: {
         name: String, 
         friends: [{firstName: String, lastName: String}]
        }

Now, I have a very basic express application that connects to the database and successfully creates ‘people’ with an empty friends array.

In a secondary place in the application, a form is in place to add friends. The form takes in firstName and lastName and then POSTs with the name field also for reference to the proper people object.

What I’m having a hard time doing is creating a new friend object and then “pushing” it into the friends array.

I know that when I do this via the mongo console I use the update function with $push as my second argument after the lookup criteria, but I can’t seem to find the appropriate way to get mongoose to do this.

db.people.update({name: "John"}, {$push: {friends: {firstName: "Harry", lastName: "Potter"}}});