mongoose-auto-increment

Mongoose plugin that auto-increments any ID field on your schema every time a document is saved.

This is the module used by mongoose-simpledb to increment Number IDs. You are perfectly able to use this module by itself if you would like. However, if you're looking to make your life easier when using mongoose then I highly recommend you check out simpledb. It's a small wrapper around mongoose but it makes it extremely easy to deal with your models and draws a clear path for how to use mongoose in your application.

Change

Added an offset for more complex constructions

Getting Started

npm install mongoose-auto-increment

Once you have the plugin installed it is very simple to use. Just get reference to it, initialize it by passing in your mongoose connection and pass autoIncrement.plugin to the plugin() function on your schema.

Note: You only need to initialize MAI once.

var mongoose = require('mongoose'),
    Schema = mongoose.Schema,
    autoIncrement = require('mongoose-auto-increment');

var connection = mongoose.createConnection("mongodb://localhost/myDatabase");

autoIncrement.initialize(connection);

var bookSchema = new Schema({
    author: { type: Schema.Types.ObjectId, ref: 'Author' },
    title: String,
    genre: String,
    publishDate: Date
});

bookSchema.plugin(autoIncrement.plugin, 'Book');
var Book = connection.model('Book', bookSchema);

That's it. Now you can create book entities at will and they will have an _id field added of type Number and will automatically increment with each new document. Even declaring references is easy, just remember to change the reference property's type to Number instead of ObjectId if the referenced model is also using the plugin.

var authorSchema = new mongoose.Schema({
    name: String
});
    
var bookSchema = new Schema({
    author: { type: Number, ref: 'Author' },
    title: String,
    genre: String,
    publishDate: Date
});
    
bookSchema.plugin(autoIncrement.plugin, 'Book');
authorSchema.plugin(autoIncrement.plugin, 'Author');

Want a field other than _id?

bookSchema.plugin(autoIncrement.plugin, { model: 'Book', field: 'bookId' });

Want that field to start at a different number than zero or increment by more than one?

bookSchema.plugin(autoIncrement.plugin, {
    model: 'Book',
    field: 'bookId',
    startAt: 100,
    incrementBy: 100
});

Your first book document would have a bookId equal to 100. Your second book document would have a bookId equal to 200, and so on.

Want to know the next number coming up?

var Book = connection.model('Book', bookSchema);
Book.nextCount(function(err, count) {

    // count === 0 -> true

    var book = new Book();
    book.save(function(err) {

        // book._id === 0 -> true

        book.nextCount(function(err, count) {

            // count === 1 -> true

        });
    });
});

nextCount is both a static method on the model (Book.nextCount(...)) and an instance method on the document (book.nextCount(...)).

Want to reset counter back to the start value?

bookSchema.plugin(autoIncrement.plugin, {
    model: 'Book',
    field: 'bookId',
    startAt: 100
});

var Book = connection.model('Book', bookSchema),
    book = new Book();

book.save(function (err) {

    // book._id === 100 -> true

    book.nextCount(function(err, count) {

        // count === 101 -> true

        book.resetCount(function(err, nextCount) {

            // nextCount === 100 -> true

        });

    });

});