Mongoose .pre('save') does not trigger

问题

I have the following model for mongoose.model('quotes'):

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);

There is an additional Schema for mongoose.model('settings') to store an incrementing number for the incrementing unique index Quote.number im trying to establish. Before each save, quotesSchema.pre('save') is called to read, increase and pass the nextQuoteNumber as this.number to the respectively next() function.

However, this entire .pre('save') function does not seem to trigger when saving a Quote elsewhere. Mongoose aborts the save since number is required but not defined and no console.log() i write into the function ever outputs anything.

回答1:

Use pre('validate') instead of pre('save') to set the value for the required field. Mongoose validates documents before saving, therefore your save middleware won't be called if there are validation errors. Switching the middleware from save to validate will make your function set the number field before it is validated.

quotesSchema.pre('validate', 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();
  });
});

回答2:

I ran into a situation where pre('validate') was not helping, hence I used pre('save'). I read that some of the operations are executed directly on the database and hence mongoose middleware will not be called. I changed my route endpoint which will trigger .pre('save'). I took Lodash to parse through the body and update only the field that is passed to the server.

router.post("/", async function(req, res, next){
    try{
        const body = req.body;
        const doc  = await MyModel.findById(body._id);
        _.forEach(body, function(value, key) {
            doc[key] = value;
        });

        doc.save().then( doc => {
            res.status(200);
            res.send(doc);
            res.end();
        });

    }catch (err) {
        res.status(500);
        res.send({error: err.message});
        res.end();
    }

});

回答3:

In some cases we can use

UserSchema.pre<User>(/^(updateOne|save|findOneAndUpdate)/, function (next) {

But i'm using "this", inside the function to get data, and not works with findOneAndUpdate trigger

I needed to use

  async update (id: string, doc: Partial<UserProps>): Promise<User | null> {
    const result = await this.userModel.findById(id)
    Object.assign(result, doc)
    await result?.save()
    return result
  }

Instead of

  async update (id: string, doc: Partial<UserProps>): Promise<User | null> {
    const result = await this.userModel.findByIdAndUpdate(id, doc, { new: true, useFindAndModify: false })
    return result
  }

来源：https://stackoverflow.com/questions/30141492/mongoose-presave-does-not-trigger

标签

node.js

mongodb

express

mongoose