Nodejs writing zip file from base64

Question

I am writing base64 encoded value to zip file. Following code i am using for writing:

var base64Data  =   base64_encoded_value;
base64Data  +=  base64Data.replace('+', ' ');
binaryData  =   new Buffer(base64Data, 'base64').toString('binary');

fs.writeFile('test.zip', binaryData, "binary", function (err) {
    console.log(err); // writes out file without error
});

Its working and test.zip file is creating, problem is then when i am extracting it, its giving me following error:

End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
unzip:  cannot find zipfile directory in one of /home/user/Node/project/public/media/written/zip4045508057.zip or
        /home/user/Node/project/public/media/written/zip4045508057.zip.zip, and cannot find /home/user/Node/project/public/media/written/zip4045508057.zip.ZIP, period.

Is there any way to do this???

score 2 · Answer 1 · answered Jan 23 '18 at 06:31

You will have to convert base64 into utf8 format. Then you can use that converted data to write file.

Try using following function to convert base64 string into utf8

/**
 * @param b64string {String}
 * @returns {Buffer}
 */
function _decodeBase64ToUtf8(b64string) {
    var buffer;
    if (typeof Buffer.from === "function") {
        // Node 5.10+
        buffer = Buffer.from(b64string, 'base64');
    } else {
        // older Node versions
        buffer = new Buffer(b64string, 'base64');
    }

    return buffer;
}

I have used this to create ZIP file using base64 data

score 0 · Answer 2 · answered Jun 28 '19 at 13:24

Alternative way to extract .zip file from a base64 string is to using npm package mws-extract-document

const mwsExtract = require('mws-extract-document');

const dist = './folder/to/document.zip';
const base64String = ''; //located at PdfDocument data response from MWS api.

// PROMISE
mwsExtract(base64String, dist)
          .then((msg)=>{
            // file saved. do something here...
            console.log(msg);
          })
          .catch(err)=>{
            console.log(err);
          });

Nodejs writing zip file from base64

2 Answers2