multer的动态大小限制答案

【问题标题】：dynamic size limit for multermulter的动态大小限制
【发布时间】：2022-10-17 19:56:22
【问题描述】：

我有一个这样的 multer 中间件。我有一个设置表，其中有上传大小限制。 get size limit 是一个异步函数，它从这个模型中获取数据。但我不能在 multer 文件大小中使用它。因为它需要在它后面等待。我能做些什么？我想在设置中设置限制大小

const multer = require("multer");
const SettingModel = require("../../models/Setting");
const SequelizeService = require("../app/sequelize/sequelize.service");
let Setting = new SequelizeService(SettingModel);

async function getSizeLimit() {
  let setting = await Setting.findOne({ raw: true });
  return 1024 * 1024 * setting.sizeLimit;
}
const storage = multer.diskStorage({
  destination: function (req, file, cb) {
    cb(null, "./uploads/");
  },
  filename: function (req, file, cb) {
    cb(null, file.originalname.replace(/\s+/g, ""));
  },
});

const fileFilter = (req, file, cb) => {
  // let response = new Response();
  if (
    file.mimetype === "image/jpeg" ||
    file.mimetype === "image/png" ||
    file.mimetype === "image/webp"
  ) {
    cb(null, true);
  } else {
    cb(new Error("Not an image! Please upload an image.", 400), false);
  }
};

exports.upload = multer({
  storage: storage,
  limits: {
    fileSize: getSizeLimit(),
  },

  fileFilter: fileFilter,
});

【问题讨论】：

标签： node.js express multer

【解决方案1】：

我通过缓存我的设置并将中间件更改为：

let multer = require("multer");
const cache = require("memory-cache");

upload_image = function (req, res, next) {
  try {
    let limit = cache.get("sizeLimit");
    let upload = multer({
      storage: multer.diskStorage({
        destination: function (req, file, cb) {
          cb(null, "./uploads/");
        },
        filename: function (req, file, cb) {
          cb(null, file.originalname.replace(/s+/g, ""));
        },
      }),
      limits: {
        fileSize: limit * 1024 * 1024,
      },
      onError: function (err, next) {
        next(err);
      },
      fileFilter: (req, file, cb) => {
        if (
          file.mimetype === "image/jpeg" ||
          file.mimetype === "image/png" ||
          file.mimetype === "image/webp"
        ) {
          cb(null, true);
        } else {
          cb(new Error("Not an image! Please upload an image.", 400), false);
        }
      },
    });

    upload.single("photo")(req, res, function (err) {
      if (err) {
        next(err);
      }
      next();
    });
  } catch (error) {
    throw new Error(error);
  }
};

exports.upload_image = upload_image;

【讨论】：