How to decode base64 PDF string in Flutter?

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.

hello, did you manage to do it??

Andrii Havrylyak
– Andrii Havrylyak

2022-08-09 16:57:16 +00:00
Commented Aug 9, 2022 at 16:57 — Andrii Havrylyak
– Andrii Havrylyak, Commented Aug 9, 2022 at 16:57

Daanzel · Accepted Answer · 2019-09-26 06:21:22Z

15

@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

answered Sep 26, 2019 at 6:21

Daanzel

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2 Comments

Mohd Sadham Over a year ago

'File' isn't a function. Try correcting the name to match an existing function, or define a method or function named 'File'. How to fix it.

Nikolay Atanasov Over a year ago

Import dart:io instead of dart:http

Mehedi Hasan Shifat · Accepted Answer · 2021-07-09 17:24:02Z

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

answered Jul 9, 2021 at 17:24

Mehedi Hasan Shifat

7409 silver badges22 bronze badges

Comments

Swift · Accepted Answer · 2019-04-10 01:41:45Z

1

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
...

edited Apr 10, 2019 at 1:41

answered Apr 9, 2019 at 19:26

Swift

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4 Comments

markhorrocks Over a year ago

I get "The argument type "int' can't be assigned to the parameter type 'String'"

markhorrocks Over a year ago

There's not enough code here for me to figure out how this works. Where do II get "pdf"?

Swift Over a year ago

@markhorrocks pdf is a flutter plugin from here. I did hyperlink it in my answer

Andrii Havrylyak Over a year ago

@markhorrocks hello, did you manage to do it??

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