The feature is not well (read: at all) documented, but after reading through the source code, I came up with the following solution.
Create your collection schema.
var Counters = new Schema({
_id: String,
next: Number
});
Create a static method on the schema which will expose the findAndModify method of the model's collection.
Counters.statics.findAndModify = function (query, sort, doc, options, callback) {
return this.collection.findAndModify(query, sort, doc, options, callback);
};
Create your model.
var Counter = mongoose.model('counters', Counters);
Find and modify!
Counter.findAndModify({ _id: 'messagetransaction' }, [], { $inc: { next: 1 } }, {}, function (err, counter) {
if (err) throw err;
console.log('updated, counter is ' + counter.next);
});
Bonus
Counters.statics.increment = function (counter, callback) {
return this.collection.findAndModify({ _id: counter }, [], { $inc: { next: 1 } }, callback);
};
Counter.increment('messagetransaction', callback);
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