node.js - 递增 Mongoose 数字字段的优雅方法

增加猫鼬数字字段的最优雅方法是什么？

var Book = new Schema({
   name: String,
   total: Number
})

如何在API中增加它？

var book = new Book({
   name: req.body.name,
   total: ?
});

book.save(callback);

最佳答案

您可以编写一个猫鼬插件来拦截保存调用并从计数器集合中返回当前计数器。

猫鼬插件

var mongoose = require('mongoose');
var Schema = mongoose.Schema;

module.exports = function(schema, options) {
    var options = options || {};
    options.name = options.name || 'generic';
    options.field = options.field || 'counter';

    var counterSchema = new Schema({ name : String, counter : Number });
    var CounterModel = mongoose.model('counters', counterSchema);

    schema.pre('save', function (next) {
        if (!this.isNew) {
            return next();
        }

        var self = this;

        CounterModel.findOneAndUpdate(
            { name : options.name },
            {
                $inc : { counter : 1 }
            },
            { upsert : true }, function(err, counter) {
                if (err) { return next(err) };

                self.set(options.field, counter.counter);

                next();
        });
    });
}

该插件知道在名为counters的集合中保留多个命名计数器。

使用猫鼬插件

var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var counter = require('./plugin');

var TestSchema = new Schema({ counter : Number });
TestSchema.plugin(counter, { name : 'tests', counter : 'counter' });

var TestModel = mongoose.model('tests', TestSchema);

mongoose.connect('mongodb://localhost', function(err) {
    TestModel.create({}, function(err, test) {
        console.log(err, test);

        test.save(function(err, test) {
            console.log(err, test);
        });
    });
});