MongoDB 自增id

const Mongoose = require('mongoose');
const Schema = Mongoose.Schema;

let counter = 1;
let CountedId = {type: Number, default: () => counter++};

const ModelSchema = new Schema({
    id: CountedId,
    // ....
});

const Model = Mongoose.model('Model', ModelSchema);

module.exports = Model;

Model.find({ id: { $gt: 0 } }).sort({ id: -1 })
    .then(([first, ...others]) => {
        if (first)
            counter = first.id + 1;
    });