Download file from API, encoding problem

[akshaychand0585]

Hello there,

Hope everyone is doing well! I am new to ServiceNow and I am struggling to download a file from API. This API returns file content with mimetype and contentdisposition. Mainly I have 2 problems with my code.

First, this code will download the file, but I am getting an error opening the pdf, error says: "This file is damaged and could not be repaired". So not sure what is going wrong. Even if I hardcode some string, I still cannot download any pdf with this code.

Second, I cannot see the contents of the file (English characters) in console. Am I doing encoding and decoding correctly? 

I have attached the images of data conversion at each step: data.responseBody (from Server Script), after converting it into bytes via atob, blob and pdf error. Your help is greatly appreciated. Thanks in advance.

This is my ServerSide script:

if (input && input.action == 'downloadFile') {

var dwnld = new sn_ws.RESTMessageV2('xxxxxxx Api', 'Download File');

dwnld.setStringParameterNoEscape('docType', input.selectedContainer);

dwnld.setQueryParameter('xxx', input.xx.xxx);

    dwnld.setQueryParameter('xxx', input.xx.xx); 

    dwnld.setHttpMethod('GET');

    var dwnld_response = dwnld.execute();

    var dwnld_responseBody = dwnld_response.getBody();

    var base64ResponseBody = GlideStringUtil.base64Encode(dwnld_responseBody);

gs.info(base64ResponseBody);

    var contentDisposition = dwnld_response.getHeader('Content-Disposition');

    var filename = extractFilename(contentDisposition);

    var mimeType = dwnld_response.getHeader('Content-Type') || 'application/octet-stream';

data.mimeType = mimeType;

data.responseBody = base64ResponseBody;

data.fileName = filename;

data.contentDisposition = contentDisposition; 

}

This is my Client Script:

$scope.downloadFile = function(item){

    $scope.downloadDetails = item;

    c.data.action = 'downloadFile';

    c.data.fileObj = item;

c.data.selectedContainer = $scope.xxx;

  c.server.update().then(function(results) {

        c.data.action = '';

        // Decode base64 response

        var binaryString = window.atob(c.data.responseBody);

        var len = binaryString.length;

        var bytes = new Uint8Array(len);

        for (var i = 0; i < len; i++) {

            bytes[i] = binaryString.charCodeAt(i);

        } 

        var blob = new Blob([bytes], { type: c.data.mimeType }); 

        var url = URL.createObjectURL(blob);

        var a = document.createElement('a');

        a.href = url;

        a.download = c.data.fileName;

        a.style.display = 'none';

        document.body.appendChild(a);

        a.click();

        document.body.removeChild(a);

        window.URL.revokeObjectURL(url);

    });