Express 具有不同文件大小限制的多个多字段

我在做特快js multer。我上传了多个带有格式验证和大小限制的文件字段。 现在，我试图在fileFilter或multer limits中对每个文件字段设置限制，但对不同的文件字段无效。 如何在multer中上载具有不同文件大小限制的文件

const storage = multer.diskStorage({
                     destination: function(req, file, cb) {
                                      cb(null, './public/images/');
                     },
                     filename: function(req, file, cb) {
                                      cb(null, file.originalname );
                     }
                });
const fileFilter = (req, file, cb) => {
  if (file.mimetype == "image/png" || file.mimetype == "image/jpg" || file.mimetype == "image/jpeg") {
      cb(null, true);
    } else if (file.fieldname === "brochurefile" && file.mimetype == "application/pdf"){
      console.log("file.buffer.byteLength === ", req.files.brochurefile[0]);
      cb(null, true);
    } else {
      cb(null, false);
      return cb({message:'Only .png, .jpg and .jpeg format allowed!'}, false);
    }
  }
const upload = multer({ storage: storage, fileFilter: fileFilter, limits: { fileSize: 2097152 }});
router.post("/post/", upload.fields([{name:'logoimage', maxCount: 1}, 
                                     {name:'collegeimage', maxCount: 1}, 
                                     {name:'bannarimage', maxCount: 1}, 
                                     {name:'brochurefile', maxCount: 1}, 
                                     {name:'collegegallary'}]);, (req,res) => {});