Plugins

Schemas are pluggable, that is, they allow for applying pre-packaged
capabilities to extend their functionality.

Suppose that we have several collections in our database and want
to add last-modified functionality to each one. With plugins this
is easy. Just create a plugin once and apply it to each Schema:

// lastMod.js
module.exports = exports = function lastModifiedPlugin (schema, options) {
  schema.add({ lastMod: Date })

  schema.pre('save', function (next) {
    this.lastMod = new Date
    next()
  })

  if (options && options.index) {
    schema.path('lastMod').index(options.index)
  }
}

// in your schema files
var lastMod = require('./lastMod');

var Game = new Schema({ ... });

Game.plugin(lastMod);

var Player = new Schema({ ... });

Player.plugin(lastMod, { index: true });

In the example above we added last-modified functionality to both the Game and Player schemas. We also took advantage of options passing supported by the plugin() method to dynamically define an index on the Player.

Mongoose

Plugins