How does Mongoose's save callback work?
The save function's callback will accept three arguments :
- The error
- The document that was saved
- The number of rows affected
The arguments are listed here
Note that the second argument, the document, must be the same document that is calling the save
You can name the arguments however you want, you're not casting it to an object or anything like that. It's simply a name that you want to use to refer it to in your function's body.