I am trying to convert a blob object to a pdf and download it.
So far I've tried the following:
var downloadLink = document.createElement('a');
downloadLink.target = '_blank';
downloadLink.download = 'name_to_give_saved_file.pdf';
// convert downloaded data to a Blob
var blob = new Blob([file.$binary], { type: 'application/pdf' });
// create an object URL from the Blob
var URL = window.URL || window.webkitURL;
var downloadUrl = URL.createObjectURL(blob);
// set object URL as the anchor's href
downloadLink.href = downloadUrl;
// append the anchor to document body
document.body.append(downloadLink);
// fire a click event on the anchor
downloadLink.click();
The file size seems to be correct, but I cant view it since it seems to be damaged.
Viewing the PDF inside of my html file works like this:
$('#test').html('<embed width=100% height=100%'
' type="application/pdf"'
' src="data:application/pdf;base64,'
escape(file.$binary)
'"></embed>')
This works without any problems!
Now to my question... why is one working and the other one isn't?
Thanks for your help...
CodePudding user response:
Your file.$binary
is not binary data (even though the object name is `$binary). It's actually a string containing the base64 representation of binary data.
So, before making a Blob
, you need to convert the string to the binary data.
You can do so using the following (from https://stackoverflow.com/a/16245768):
const b64toBlob = (b64Data, contentType='', sliceSize=512) => {
const byteCharacters = atob(b64Data);
const byteArrays = [];
for (let offset = 0; offset < byteCharacters.length; offset = sliceSize) {
const slice = byteCharacters.slice(offset, offset sliceSize);
const byteNumbers = new Array(slice.length);
for (let i = 0; i < slice.length; i ) {
byteNumbers[i] = slice.charCodeAt(i);
}
const byteArray = new Uint8Array(byteNumbers);
byteArrays.push(byteArray);
}
const blob = new Blob(byteArrays, {type: contentType});
return blob;
}
Then you can do
var blob = b64toBlob(file.$binary, 'application/pdf');
Looking at other answers on the same question (https://stackoverflow.com/a/36183085), there is a smaller way to do this:
const b64toBlob = (base64, type = 'application/octet-stream') =>
fetch(`data:${type};base64,${base64}`).then(res => res.blob())
Then you can still do
var blob = b64toBlob(file.$binary, 'application/pdf');