异步操作后，MongoDB 中的文件链接数组为空答案

【问题标题】：Array of files' links is empty in Mongodb after asynchronous operations异步操作后，MongoDB 中的文件链接数组为空
【发布时间】：2023-03-03 05:28:19
【问题描述】：

我的 Apollo 变异函数获取 2 个文件数组作为参数。然后我将它写入文件系统，将它们的位置推送到数组中。之后，我希望将数组写入 MongoDB，但由于异步，mongo 有空字段。我该如何处理？

const { createWriteStream } = require("fs");
const path = require('path');
const Post = require('../../models/Post');
const checkAuth = require('../../utils/check-auth');

module.exports = {
  Mutation: {
    async addPost(_, { postInput: { title, description, pictures, panoramas, price, location } }, ctx) {
      const anon = checkAuth(ctx);
      let pics = [];
      let pans = [];

      pictures.map(async (el) => {
        const { createReadStream, filename } = await el;

        await new Promise(res =>
          createReadStream()
            .pipe(createWriteStream(path.join("static/images", filename)))
            .on("close", res)
        );
        pics.push(`static/images/, ${filename}`);
      })
      panoramas.map(async (el) => {
        const { createReadStream, filename } = await el;

        await new Promise(res =>
          createReadStream()
            .pipe(createWriteStream(path.join("static/images", filename)))
            .on("close", res)
        );
        pans.push(path.join("static/images", filename));
      })

      const newPost = new Post({
        title,
        description,
        price,
        pictures: pics,
        panoramas: pans,
        createdAt: new Date().toISOString(),
        userId: anon.id,
        location,
      });

      const res = await newPost.save();
      console.log(res)
      return true;
    }
  }
}

【问题讨论】：

标签： node.js mongodb express asynchronous apollo

【解决方案1】：

你应该等到所有的承诺都解决了，然后才继续创建一个新文档。

async function addPost(_, {postInput: {title, description, pictures, panoramas, price, location}}, ctx) {
    const anon = checkAuth(ctx);
    let pans = [];
    let pics = [];

    pictures.map(async (el) => {
        pics.push(
            new Promise(async (resolve, reject) => {
                const {createReadStream, filename} = await el;

                await new Promise(res =>
                    createReadStream()
                        .pipe(createWriteStream(path.join("static/images", filename)))
                        .on("close", res)
                );
                resolve(`static/images/, ${filename}`);
            })
        )
    });

    await Promise.all(pics);

    panoramas.map(async (el) => {
        pans.push(
            new Promise(async (resolve, reject) => {
                const {createReadStream, filename} = await el;

                await new Promise(res =>
                    createReadStream()
                        .pipe(createWriteStream(path.join("static/images", filename)))
                        .on("close", res)
                );
                resolve(path.join("static/images", filename));
            }));
    });

    await Promise.all(pans);

    const newPost = new Post({
        title,
        description,
        price,
        pictures: pics,
        panoramas: pans,
        createdAt: new Date().toISOString(),
        userId: anon.id,
        location,
    });

    const res = await newPost.save();
    console.log(res)
    return true;
}

这是一个简单的示例，我建议您稍微清理一下并添加某种错误处理。

【讨论】：