mongoose-lifecycle

Mongoose plugin adding lifecyle events to the model class.

Installation

Add the plugin as a dependency to your project in package.json:

{
  "name": "myproject",
  ...
  "dependencies": {
    "mongoose": "2.6.5",
    "mongoose-lifecycle": "1.0.0",
    ...
  },
}

And run npm install again.

Usage

Initialization is straightforward:

var Book = new Schema({ ... });
Book.plugin(require('mongoose-lifecycle'));
module.exports = mongoose.model('Book', Book);

Now the model emits lifecycle events before and after persistence operations:

• beforeInsert
• afterInsert
• beforeUpdate
• afterUpdate
• beforeSave (called for both inserts and updates)
• afterSave (called for both inserts and updates)
• beforeRemove
• afterRemove

You can listen to these events directly on the model.

var Book = require('path/to/models/book');
Book.on('beforeInsert', function(book) {
  console.log('A new book "%s" was inserted', book.title);
});

The beforeInsert event is emitted just before a new document is persisted:

var book = new Book();
book.title = 'War and Peace';
book.save(); // logs the book title to the console
});

Why Not Use The save and remove events?

Because you may not have access to the right class to register them.

// if you register an event listener on the Schema class, it works
// in models/book.js
var Book = new Schema({ ... });
Book.pre('save', function(next) {
  console.log('A new book "%s" was inserted', this.title);
  next();
});

// if you register an event listener on the Model class, it doesn't work
// in models/book.js
var Book = new Schema({ ... });
module.exports = mongoose.model('Book', Book);
// in a controller class
var Book = require('path/to/models/book'); // Book is a Model, not a Schema
Book.pre('save', function(next) {
  console.log('A new book "%s" was inserted', this.title);
  next();
});

The plugin does the work of finding the Schema back from the Model class. It also allows you to use the standard on() method to register event listeners, instead of the custom pre() and post() Mongoose methods. Lastly, it makes a difference between insert and update persistence operations, while Mongoose only provides a save event.

License

MIT License