从快递路线下载图片

Question

I have an express server running with the following route:

exports.getUserFile = function (req, resp) {
      let filePath = path.join(__dirname, 'storage', req.params.fileName);
      resp.download(filePath);
  });
}

In my web app i'm calling this route and trying to save the file locally using file-saver :

let req = request.get('/users/' + userId + '/files/' + file.name);
req.set('Authorization', 'Bearer ' + this.state.jsonWebToken);
req.end((err, resp) => {
  let f = new File([resp.text], file.name, {type: resp.type});
  fileSaver.saveAs(f);
});

If the file is plain text then it works ok, but for other file types like images i'm not able to open the file (it's 'corrupt').

This is what the response looks like:

Do I need to decode the data in some way first? What is the correct way to save the content of the file?

Answer 1

I haven't used express for a long time ago and I'm typing from mobile, it's seems a encoding issue, so it's seems that you're a sending raw image, you will need to encode it in base64 try something like:

//Here your saved file needs to be encoded to base 64.
var img = new Buffer(data, 'base64');

   res.writeHead(200, {
     'Content-Type': 'image/png',
     'Content-Length': img.length
   });
   res.end(img);

Where data is your saved image, If you can render the image you just add the headers for download or just chain method download.

Answer 2

If you're using superagent to perform the requests, you can explicitly set the response type to "blob" , which would prevent any attempts to decode the response data. The binary data will end up in resp.body :

req.responseType('blob').end((err, resp) => {
  saveAs(resp.body, file.name);
});

Answer 3

If you want to download the image as attachment in the page you can use res

exports.getUserFile = function (req, resp) {
  let filePath = path.join(__dirname, 'storage', req.params.fileName);
  var check = fs.readFileSync(__dirname+req.params.fileName);
  resp.attachment(req.params.fileName); // The name of the file to be saved as. Eg Picture.jpg
  res.resp(check)  // Image buffer read from the path.
});
}

Reference:

http://expressjs.com/en/api.html#res.attachment

http://expressjs.com/en/api.html#res.end

Hope this helps.