Node express save pdf from binary string

Question

I have a problem saving a pdf file from binary data. I get the binary from a web service and my express server (as middleware) should send the file to the client. The problem is that client and adobe acrobat reader show a blank pdf, so I'm thinking that I done some error saving/encoding the binary data.

exports.downloadReceipt = function(req, res) {
  var idPrenotazione = req.params.idPrenotazione;
  var options = {
    'method': 'GET',
    'uri': api_url + '/ricevute/'+idPrenotazione,
    'headers': {
      'Authorization': req.get('Authorization')
    }
  }

  request(options, function(error, response, body) {
    var date = new Date().getTime();
    var filename = 'ricevuta_'+idPrenotazione+'_'+date+'.pdf';
    var file = folderPath + filename;

  fs.writeFile(file, body, function(err) {
    if(err)
      console.log(err);
    else
      console.log("The file was saved!");
  });      

  // for the moment I only save the file on server file system
  res.end();


  });
}

I also tried to use createWriteStream instead of writeFile, with and without encoding option

  var options = { encoding: 'binary' };
  var wstream = fs.createWriteStream(file_);
  wstream.write(body);
  wstream.end();

The string that I get from web service is something like this:

%PDF-1.5
%����
2 0 obj
<</Length1 17948/Length 9587/Filter/FlateDecode>>stream
x��{y`՝���!ɖ-Y�iɖF�e˖,۲lَ��v�$���s8v��B�$�(4nHiI�RP��@�n�����׶���-P�-Wbi����H��������y��|���^��}3�p9� -[3�~�+���< ��l�E���E7�7��Њ�+�l\�1��?P��rt�
�G��!}ؿj���ɿ~�@�+H߰
o�t�&��u��5m�??ن�5�~���e�����й��޼�3����#��~���ԷX��%����������
k\��\z���d���O�x@�A9(-�A>�@`�B0�  �`+ؠ���Q��\ �<��R�A��*��*A5�@-��"P
�Fh�f�-�

[.....]

0000042111 00000 n 
0000042252 00000 n 
0000042393 00000 n 
trailer
<</Root 7 0 R/ID [<10edca6daaad5a49919bad108ba77f0a><492e2d9a8ca810421f41667217724e69>]/Info 4 0 R/Size 183>>
%iText-5.5.8
startxref
173008
%%EOF

What I'm doing wrong? I just have a function that get an image (from the same web service) in base64 and I save it on server file system with writeFile and it works well.

Thanks for help

Alessandro Mercurio · Accepted Answer · 2016-09-14 14:43:17Z

25

I found the problem! I needed to specify 'encoding': 'binary' in request options and in writeFile: fs.writeFile(file, body, 'binary', function(err) {.

Now I can open and send correctly image and pdf from binary string.

answered Sep 14, 2016 at 14:43

Alessandro Mercurio

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4 Comments

Hariharan AR Over a year ago

@Ciotto I tried this code. It create a pdf file. but, i can't open the file. it show me the "Can't validate the signature"

Alessandro Mercurio Over a year ago

Hi @HariharanAR unfortunately I didn't work on this project anymore and I never managed pdf with signature. Can you share your code to be sure that you do it correctly?

sudonitin Over a year ago

I am getting a blank PDF with the expected number of pages. @Ciotto

Adam Mendoza Over a year ago

Yup, works! thx

valentin · Accepted Answer · 2023-04-11 14:06:08Z

10

for those who have a blank pdf and are using axios, you have to add these axios request params:

responseType: "arraybuffer",
responseEncoding: "binary"

Source : here

edited Apr 11, 2023 at 14:06

valentin

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answered Mar 3, 2022 at 10:55

hamzawi

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