Mongoose操作超时求助：deleteMany/insertOne缓冲超时10000ms

运行Node.js代码时，控制台先输出Database connected提示数据库已连接，但随后抛出超时错误：

MongooseError: Operation campgrounds.deleteMany() buffering timed out after 10000ms

即使删除deleteMany({})代码，依然会出现另一超时错误：

MongooseError: Operation campgrounds.insertOne() buffering timed out after 10000ms

尝试添加catch捕获错误，问题依旧存在。代码如下：

const mongoose = require("mongoose");
const cities = require("./cities");
const { places, descriptors } = require("./seedHelpers");
const Campground = require("../models/campground");

mongoose.connect("mongodb://127.0.0.1:27017/camp-spot");

const db = mongoose.connection;

db.on("error", console.error.bind(console, "connection error:"));
db.once("open", () => {
  console.log("Database connected");
});

const sample = (array) => array[Math.floor(Math.random() * array.length)];

const seedDB = async () => {
  await Campground.deleteMany({});
  for (let i = 0; i < 50; i++) {
    const random1000 = Math.floor(Math.random() * 1000);
    const price = Math.floor(Math.random() * 20) + 10;
    const camp = new Campground({
      location: `${cities[random1000].city}, ${cities[random1000].state}`,
      title: `${sample(descriptors)} ${sample(places)}`,
      image: "https://source.unsplash.com/collection/483251",
      description:
        "Lorem ipsum dolor sit amet consectetur adipisicing elit. Quibusdam dolores vero perferendis laudantium, consequuntur voluptatibus nulla architecto, sit soluta esse iure sed labore ipsam a cum nihil atque molestiae deserunt!",
      price,
    });
    await camp.save();
  }
};

seedDB().then(() => {
  mongoose.connection.close();
});

核心问题是数据库操作早于连接完成时机执行。mongoose.connect()是异步操作，现有代码在调用连接后直接执行seedDB()，此时Mongoose还在缓冲数据库请求，超时后就会抛出错误。

方法一：在连接成功回调中执行操作 #

将seedDB()调用放到db.once("open")的回调内，确保数据库完全连接后再执行数据操作：

const mongoose = require("mongoose");
const cities = require("./cities");
const { places, descriptors } = require("./seedHelpers");
const Campground = require("../models/campground");

mongoose.connect("mongodb://127.0.0.1:27017/camp-spot");

const db = mongoose.connection;

db.on("error", console.error.bind(console, "connection error:"));
db.once("open", async () => {
  console.log("Database connected");
  await seedDB();
  mongoose.connection.close();
});

const sample = (array) => array[Math.floor(Math.random() * array.length)];

const seedDB = async () => {
  await Campground.deleteMany({});
  for (let i = 0; i < 50; i++) {
    const random1000 = Math.floor(Math.random() * 1000);
    const price = Math.floor(Math.random() * 20) + 10;
    const camp = new Campground({
      location: `${cities[random1000].city}, ${cities[random1000].state}`,
      title: `${sample(descriptors)} ${sample(places)}`,
      image: "https://source.unsplash.com/collection/483251",
      description:
        "Lorem ipsum dolor sit amet consectetur adipisicing elit. Quibusdam dolores vero perferendis laudantium, consequuntur voluptatibus nulla architecto, sit soluta esse iure sed labore ipsam a cum nihil atque molestiae deserunt!",
      price,
    });
    await camp.save();
  }
};

方法二：用async/await等待连接完成 #

通过mongoose.connect()返回的Promise等待连接建立，写法更简洁且支持错误捕获：

const mongoose = require("mongoose");
const cities = require("./cities");
const { places, descriptors } = require("./seedHelpers");
const Campground = require("../models/campground");

const sample = (array) => array[Math.floor(Math.random() * array.length)];

const seedDB = async () => {
  await Campground.deleteMany({});
  for (let i = 0; i < 50; i++) {
    const random1000 = Math.floor(Math.random() * 1000);
    const price = Math.floor(Math.random() * 20) + 10;
    const camp = new Campground({
      location: `${cities[random1000].city}, ${cities[random1000].state}`,
      title: `${sample(descriptors)} ${sample(places)}`,
      image: "https://source.unsplash.com/collection/483251",
      description:
        "Lorem ipsum dolor sit amet consectetur adipisicing elit. Quibusdam dolores vero perferendis laudantium, consequuntur voluptatibus nulla architecto, sit soluta esse iure sed labore ipsam a cum nihil atque molestiae deserunt!",
      price,
    });
    await camp.save();
  }
};

(async () => {
  try {
    await mongoose.connect("mongodb://127.0.0.1:27017/camp-spot");
    console.log("Database connected");
    await seedDB();
  } catch (err) {
    console.error("Seeding failed:", err);
  } finally {
    mongoose.connection.close();
  }
})();

内容的提问来源于stack exchange，提问作者andrew shin