How to decode base64 PDF string in Flutter? - node.js

Question

I know there is a package called dart:convert which let me decode base64 image. But apparently, it doesn't work with pdf files. How can I decode the base64 PDF file in Flutter?
I want to store it in Firebase Storage (I know how to do it) but I need the File variable to do it.
I have a web service written in node js where I have a POST route. There, I create a pdf file and encode it to base 64. The response is a base64 string, look at the code.
router.post('/pdf', (req, res, next) => {
//res.send('PDF');
const fname = req.body.fname;
const lname = req.body.lname;
var documentDefinition = {
content: [ write your pdf with pdfMake.org ],
styles: { write your style };
const pdfDoc = pdfMake.createPdf(documentDefinition);
pdfDoc.getBase64((data) => {
res.send({ "base64": data });
});
});
As you can see, it returns the pdf as a base64 string.
Now, in Flutter, I have written this:
http.post("https://mypostaddreess.com",body: json.encode({"data1":"data"}))
.then((response) {
print("Response status: ${response.statusCode}");
print("Response body: ${response.body}");
var data = json.decode(response.body);
var pdf = base64.decode(data["base64"]);
});
}
I have the PDF in the variable 'pdf' as you see. But I don't know how to decode it to download the pdf or show it in my Flutter app.

Answer 1

#SwiftingDuster
a little added, maybe besides decoding, it's also necessary to create a pdf file and open it.
createPdf() async {
var bytes = base64Decode(widget.base64String.replaceAll('\n', ''));
final output = await getTemporaryDirectory();
final file = File("${output.path}/example.pdf");
await file.writeAsBytes(bytes.buffer.asUint8List());
print("${output.path}/example.pdf");
await OpenFile.open("${output.path}/example.pdf");
setState(() {});
}
library needed:
1. open_file
2. path_provider
3. pdf

Answer 2

I think it's better to get the BufferArray and convert it into a pdf file.
Check out my answer from here : Get pdf from blob data

Answer 3

This should convert base64 encoded pdf data into a byte array.
import 'packages:dart/convert.dart';
List<int> pdfDataBytes = base64.decode(pdfBase64)
.map((number) => int.parse(number));
The pdf and the image plugins seems to suit your needs for displaying pdf.
The code should be roughly like so:
import 'package:pdf/pdf.dart';
import 'package:image/image.dart';
...
Image img = decodeImage(pdfDataBytes);
PdfImage image = PdfImage(
pdf,
image: img.data.buffer.asUint8List(),
width: img.width,
height: img.height);
// Display it somehow
...