Mongodb Mongoose.pre('save') 不会触发

我有以下mongoose.model('quotes')美元的型号:

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

var quotesSchema = new Schema({
    created: { type: String, default: moment().format() },
    type: { type: Number, default: 0 },
    number: { type: Number, required: true },

    title: { type: String, required: true, trim: true},
    background: { type: String, required: true },

    points: { type: Number, default: 1 },
    status: { type: Number, default: 0 },
    owner: { type: String, default: "anon" }
});

var settingsSchema = new Schema({
    nextQuoteNumber: { type: Number, default: 1 }
});

// Save Setting Model earlier to use it below
mongoose.model('settings', settingsSchema);
var Setting = mongoose.model('settings');

quotesSchema.pre('save', true, function(next) {
  Setting.findByIdAndUpdate(currentSettingsId, { $inc: { nextQuoteNumber: 1 } }, function (err, settings) {
    if (err) { console.log(err) };
    this.number = settings.nextQuoteNumber - 1; // substract 1 because I need the 'current' sequence number, not the next
    next();
  });
});

mongoose.model('quotes', quotesSchema);

对于mongoose.model('settings')，还有一个额外的模式，用于存储递增的唯一索引Quote.number的递增数字.在每次保存之前，调用quotesSchema.pre('save')来读取、增加nextQuoteNumber，并将其作为this.number传递给相应的next()函数.

然而，在其他地方保存Quote时，整个.pre('save')函数似乎不会触发.Mongoose中止保存，因为number是必需的，但没有定义，而且我写入函数的console.log()从未输出任何内容.