猫鼬虚拟填充无限循环

Question

我试图用与其相关的教程填充标签，当我在查询上使用 .populate() 时，它可以工作，但是当我直接在模型上执行此操作时，我有一个无限循环。

这是我的代码：

标签.js

const mongoose = require("mongoose");

const tagSchema = new mongoose.Schema(
  {
    name: {
      type: String,
      required: true,
      unique: true,
      trim: true
    }
  },
  {
    toObject: { virtuals: true },
    toJSON: { virtuals: true }
  }
);

tagSchema.virtual("tutorials", {
  ref: "Tutorial",
  foreignField: "tags",
  localField: "_id"
});

tagSchema.pre(/^find/, function(next) {
  // That's the code that causes an infinite loop
  this.populate({
    path: "tutorials",
    select: "-__v"
  });

  next();
});

const Tag = mongoose.model("Tag", tagSchema);

module.exports = Tag;

教程.js

const mongoose = require('mongoose');

const tutorialSchema = new mongoose.Schema({
  title: {
    type: String,
    required: true,
    unique: true,
    trim: true
  },
  tags: {
    type: [
      {
        type: mongoose.Schema.ObjectId,
        ref: 'Tag'
      }
    ]
  }
});

const Tutorial = mongoose.model('Tutorial', tutorialSchema);

module.exports = Tutorial;

我想知道是什么导致了无限循环以及为什么它适用于查询但不适用于模型？谢谢 ！

编辑

这是有效的代码

标签.js

const mongoose = require("mongoose");

const tagSchema = new mongoose.Schema(
  {
    name: {
      type: String,
      required: true,
      unique: true,
      trim: true
    }
  },
  {
    toObject: { virtuals: true },
    toJSON: { virtuals: true }
  }
);

tagSchema.virtual("tutorials", {
  ref: "Tutorial",
  foreignField: "tags",
  localField: "_id"
});

const Tag = mongoose.model("Tag", tagSchema);

module.exports = Tag;

教程.js

const mongoose = require('mongoose');

const tutorialSchema = new mongoose.Schema({
  title: {
    type: String,
    required: true,
    unique: true,
    trim: true
  },
  tags: {
    type: [
      {
        type: mongoose.Schema.ObjectId,
        ref: 'Tag'
      }
    ]
  }
});

const Tutorial = mongoose.model('Tutorial', tutorialSchema);

module.exports = Tutorial;

TagController.js

const Tag = require('./../models/tagModel');

exports.getAllTags = async (req, res) => {
  try {
    const docs = await Tag.find().populate({
      path: 'tutorials',
      select: '-__v'
    });

    res.status(200).json({
      // some code
    });
  } catch(err) => {
    // some code
  }
});

Answer 1

我最近遇到了同样的问题，花了相当长的时间来解决它，在我的例子中，两个查询相互填充并导致无限循环。