How to handle errors in mongoose?

Question

MongoDB

How to handle errors such as writing a new document whose field should be unique but repeated?
At the moment, it brings down the whole process (
I know that you can rewrite the texts of errors in your own way, like

// customize within each schema or globally like so
  var mongoose = require('mongoose');
  mongoose.Error.messages.String.enum  = "Your custom message for {PATH}.";

I hung up a handler like

mongoose.connection.on('error',function(err){
  log.error('Could not connect to mongo server!');
});

But it actually only catches errors on the connection to the database.
How to catch errors like "MongoError:E11000 duplicate key..." ?
You can tell the errors of mongoDB itself.

Answer 1

And you process in the callback that you pass to .save. The error arrives there as the first parameter