如何防止文件上传到Multer，除非它们是图像?

As title says.

正如标题所说。

I looked everywhere, couldn't find an answer.

我到处找，找不到答案。

CODE:

代码:

var upload = multer({dest:"./public/images/uploads/", limits: {fileSize: 250000}}).single("image");

PROBLEM

问题

This does not prevent me from uploading a pdf if I choose to do so.

这并不妨碍我上传pdf，如果我选择这样做。

1 个解决方案

#1

The docs state you should use fileFilter to possibly skip files for upload.
fileFilter (https://github.com/expressjs/multer#filefilter)

文档说明应该使用fileFilter来跳过文件上传。fileFilter(https://github.com/expressjs/multer # fileFilter)

Set this to a function to control which files should be uploaded and which should be skipped. The function should look like this:

function fileFilter (req, file, cb) {

  // The function should call `cb` with a boolean
  // to indicate if the file should be accepted

  // To reject this file pass `false`, like so:
  cb(null, false)

  // To accept the file pass `true`, like so:
  cb(null, true)

  // You can always pass an error if something goes wrong:
  cb(new Error('I don\'t have a clue!'))

}

From the docs I would assume that the passed in file has a property mimetype (https://github.com/expressjs/multer#api). This could be a good hint for the decision if you want to skip.

从文档中，我假设传递的文件有一个属性mimetype (https://github.com/expressjs/multer#api)。如果你想跳过，这可能是一个很好的提示。

EDIT: this GH issues (https://github.com/expressjs/multer/issues/114#issuecomment-231591339) contains a good example for the usage. It's important to not only look at the file extension because this can easily be renamed but also take the mime-type into account.

编辑:这个GH问题(https://github.com/expressjs/multer/issues/114# issues -231591339)包含一个很好的用法示例。重要的是，不仅要查看文件扩展名，因为它很容易被重命名，而且还可以考虑mime类型。

const path = require('path');

multer({
  fileFilter: function (req, file, cb) {

    var filetypes = /jpeg|jpg/;
    var mimetype = filetypes.test(file.mimetype);
    var extname = filetypes.test(path.extname(file.originalname).toLowerCase());

    if (mimetype && extname) {
      return cb(null, true);
    }
    cb("Error: File upload only supports the following filetypes - " + filetypes);
  }
});

HTH

#1