Flutter/ get PDF file from URL - flutter

Question

void getFileFromUrl(String uri) async {
var fileName = 'testonline';
try {
var _uri = Uri.parse(uri);
var data = await http.get(_uri);
var bytes = data.bodyBytes;
var dir = await getApplicationDocumentsDirectory();
File file = File("${dir.path}/" + fileName + ".pdf");
print(dir.path);
File urlFile = await file.writeAsBytes(bytes);
_pdfController = PdfController(document: PdfDocument.openFile(dir.path));
} catch (e) {
throw Exception("Error opening url file");
}
}
Hello I am developing website with Flutter,
I would like to present PDF file on my website.
getFileFromUrl(
'https://www.w3.org/WAI/ER/tests/xhtml/testfiles/resources/pdf/dummy.pdf');
I am calling this function in inistate on my web site, this link is the testing pdf link which is valid link.
But I am getting this error.
Error: Exception: Error opening url file
at Object.throw_ [as throw] (http://localhost:58701/dart_sdk.js:5037:11)
at membership_agreement_screen._MembershipAgreementScreenState.new.getFileFromUrl
(http://localhost:58701/packages/clio_application_portal/screens/membership_agreement_screen.dart.lib.js:1312:23)
at getFileFromUrl.throw (<anonymous>)
at http://localhost:58701/dart_sdk.js:37379:38
at _RootZone.runBinary (http://localhost:58701/dart_sdk.js:37249:59)
at _FutureListener.thenAwait.handleError (http://localhost:58701/dart_sdk.js:32511:48)
at handleError (http://localhost:58701/dart_sdk.js:33044:51)
at Function._propagateToListeners (http://localhost:58701/dart_sdk.js:33070:17)
at _Future.new.[_completeError] (http://localhost:58701/dart_sdk.js:32920:23)
at async._AsyncCallbackEntry.new.callback (http://localhost:58701/dart_sdk.js:32956:31)
at Object._microtaskLoop (http://localhost:58701/dart_sdk.js:37497:13)
at _startMicrotaskLoop (http://localhost:58701/dart_sdk.js:37503:13)
at http://localhost:58701/dart_sdk.js:33274:9
Please let me know what is wrong...
I am waiting for you help..
Thanks for reading.

Answer 1

I would assume the problem is that this is a cross origin call, which is not allowed in a website. This has nothing to do with flutter though. But is a security feature enforced by the browsers.
If you want to serve some pdf file from another host than you are serving the JavaScript you have to either have control over the server hosting the PDF to add CORS headers, or add a reverse proxy on the same host of your JavaScript which proxies all requests.
Flutter describs this problem for images, but it just as well effects any http connections: https://flutter.dev/docs/development/platform-integration/web-images#cross-origin-images