Mongoose for Application Development

Understanding validation errors

When we have been creating, editing, and saving data in our project, we have been using a callback function containing two parameters: an error object and the returned data object. So far we have generally been ignoring the error object and just been saving the data, for example:

user.save(function (err, user) {
  if(err){
    console.log(err)
  } else { ...

It is in the err object that we receive the Mongoose validation errors. The error object will contain a top-level message and name, and a collection of specific errors. Each of these errors give an individual message, name, path, and type object. A typical validation failure looks like the following when sent to the console:

{ message: 'Validation failed', name: 'ValidationError', ...