Mongoose Extract Duplicate Field

This simple module extracts the name of a duplicate field from the Mongoose "duplicate key" error message object.

You can install it using npm:

npm install --save mongoose-extract-duplicate-field

The module exports a function. Once installed, you can import this function:

var extractDuplicateField = require('mongoose-extract-duplicate-field');

And call it, like so:

foo.save(function (error)
  if (error && error.code === 11000) {
    var field = extractDuplicateField(error);
 
  }
});

The extractDuplicateField function you imported extracts the name of the duplicate field and returns it synchronously. Simple but useful stuff.