Mongoose 填充。 是否可以通过参数链接 collections

Question

const mongoose = require('mongoose');
const { Schema } = mongoose;

const personSchema = Schema({
  userId: Number,
  name: String
});

const storySchema = Schema({
  author: { type: Schema.Types.Number, ref: 'Person' },
  title: String
});

const Story = mongoose.model('Story', storySchema);
const Person = mongoose.model('Person', personSchema);

Story.
  findOne({ title: 'Casino Royale' }).
  populate('author')

Tell me what you need to add to link two collections by the userId parameter

Answer 1

the populate method have some params, as the path and select . the path is the most important one, it's where you determine what field of you model you're trying to populate.

The populate method use the mongoose default generated _id for searches. So your field userId will not work in this case. If you want to use a custom ID for your models, you should add the attribute _id to your model and pass it in the creation of a document.

So, you're probably looking for this:

const personSchema = Schema({
  _id: Number,
  name: String
});

const storySchema = Schema({
  author: { type: Schema.Types.Number, ref: 'Person' },
  title: String
});

const Story = mongoose.model('Story', storySchema);
const Person = mongoose.model('Person', personSchema);

await Person.create({
  _id: 1,
  name: 'Andreas'
});

await Story.create({
  author: 1,
  title: 'Casino Royale'
});

var story = await Story
  .findOne({ title: 'Casino Royale' })
  .populate({
    path: 'author',
    select: 'name',
  });