每次使用`new mongoose.Schema`都会使用相同的默认值

Question

I have problem using uuid with new mongoose.Schema . I use it to generate unique key for a device and save it to the MongoDb using Node.js. the problem is that it uses the same UUID every time.

This is the model:

const mongoose = require('mongoose');
const uuid = require('uuid/v4');

const DeviceSchema = new mongoose.Schema({
    deviceNumberHash: {
        type: String,
        required: true
    },
    receivingKey: {
        type: String,
        default: uuid()
    }...
});

And this is what is saved in MongoDb:

Any idea what's wrong?

Answer 1

You're calling uuid and passing its return value in as the default to use.

Instead, pass in the function (by not putting () after it):

const DeviceSchema = new mongoose.Schema({
    deviceNumberHash: {
        type: String,
        required: true
    },
    receivingKey: {
        type: String,
        default: uuid // <========== No ()
    }...
});

The default can be a function per the docs (an example there uses default: Date.now to provide a default for a date field, for instance).