I am confused with the URL and Uri in dart/flutter.
I created this function to be used in my PDF viewer.
static Future<File> loadNetwork(String url) async {
final response = await http.get(Uri.parse(url));
final bytes = response.bodyBytes;
return _storeFile(url, bytes);
}
and I want to call this function to display the specific PDF after clicking a button.
onTap: () async {
setState(() {
isLoading = true;
});
final url = 'http://www.africau.edu/images/default/sample.pdf';
final file = await PDFApi.loadNetwork(url);
openPDF(context, file);
setState(() {
isLoading = false;
});
},
But, still, how do I properly use the Uri and fetch the pdf link. There is an error and I suspect I am using the function wrongly.
It says invalid internet address.
Thanks!
To convert a url to Uri use Uri.parse("url here")
Related
I have a question regarding how to view a PDF from URL.
I’m using flutter_pdfview library and I try to get a PDF from an URL and to view it in my Flutter app.
The problem is that my URL can be accessed ONLY with a token (session ID/header), but I don’t know how to pass it because is not working on the way I do it at the moment.
Here is an example of how the owner of the flutter_pdfview library is getting the PDF from an URL (without a Header): https://github.com/endigo/flutter_pdfview/blob/master/example/lib/main.dart#L49
And here is my code where I don’t know how else to pass the header than like this:
Future<File> createFileOfPdfUrl() async {
Completer<File> completer = Completer();
if (kDebugMode) {
print("Start download file from internet!");
}
try {
String url =
"$customURL.pdf";
if (kDebugMode) {
print("url: $url");
}
final filename = url.substring(url.lastIndexOf("/") + 1);
var client = HttpClient();
HttpClientRequest request = await client.getUrl(Uri.parse(url));
request.headers.add(
HttpHeaders.acceptHeader,
HeaderValue(
"text/plain", {'APPAUTH': '${widget.authService.loginToken}'})); // this method doesn't seems to work for me. I'm getting an empty PDF.
var response = await request.close();
var bytes = await consolidateHttpClientResponseBytes(response);
var dir = await getApplicationDocumentsDirectory();
if (kDebugMode) {
print("Download files");
print("${dir.path}/$filename");
}
File file = File("${dir.path}/$filename");
await file.writeAsBytes(bytes, flush: true);
completer.complete(file);
} catch (e) {
throw Exception('Error parsing asset file!');
}
return completer.future;
}
DO NOT do this:
request.headers.add(
HttpHeaders.acceptHeader, // here is the problem
HeaderValue(
"text/plain", {'APPAUTH': '${widget.authService.loginToken}'}));
SOLUTION for me:
request.headers.add("APPAUTH", "12345abcde67890defgh");
For some reason if you provide a HeaderValue you also need to provide a string value before it, which can be HttpHeaders.acceptHeader or HttpHeaders.serverHeader etc. I tried a lot of them from that enum list and none worked for me so I used the above solution where you don't need to pass that HttpHeader value type.
I have this button that uploads to Firestore a picture that the user selects and stores the picture url into a varialble to be used to update the user's information.
SELECTION BUTTON calls selectFile().
// SELECTING FILE FOR UPLOAD
Future selectFile() async {
final result = await FilePicker.platform
.pickFiles(allowMultiple: false, type: FileType.image, withData: true);
if (result == null) return;
setState(() {
pickedFile = result.files.first;
texto = Text(pickedFile!.name);
});
}
This successfully changes the state of pickedFiles and Texto variable.
Then I have this other button later in the code that calls uploadFile() and then exits the page with navigator.pop(context).
// UPLOADING FILE AND RETRIEVING DOWNLOAD LINK
Future uploadFile() async {
var fileBytes = pickedFile?.bytes;
var fileName = pickedFile?.name;
var ref = FirebaseStorage.instance.ref().child('UserImages/$fileName');
if (fileBytes == null) {
return '';
}
TaskSnapshot uploadedFile = await ref.putData(fileBytes);
url = await ref.getDownloadURL();
log(url);
if (uploadedFile.state == TaskState.success) {
setState(() { <<<<<<<<--------- setState() called after dispose() ERROR HERE
_petImage = url;
});
}
}
The function does upload the picture to FireStore and even produces a link (tested by using log(url)) but when it reaches the set state it fails.
I have no idea why this is not updating the state of the _petImage variable which stored outside of the main build(context) together with the other variables suck as pickedFile and texto. the setState work fine in other functions but in this function is not working .
what could I be doing wrong here?
It is safe to check if the state is mounted on async and then perform setState.
_() async {
if (mounted) {
setState(() {});
}
}
I am getting an error in the url part of the code, I have shown the error in the screenshot. How can I fix my code without changing its function.
Future<List<Articles>?> getNews() async {
String url = "https://jsonplaceholder.typicode.com/posts";
final response = await http.get(url);
if (response.body.isEmpty) {
final responseJson = json.decode(response.body);
News news = News.fromJson(responseJson);
return news.articles;
}
return null;}
You need to pass Uri instead of string.
final response = await http.get(Uri.parse(url));
You can assign uri something like this
var uri= Uri.https('jsonplaceholder.typicode.com', 'posts');
And if you want to add queryparametrs then use below code
final queryParameters =
{
'key' : 'value',
};
var uri= Uri.https('jsonplaceholder.typicode.com', 'posts',queryParameters);
And use this uri in place of Url.
final response = await http.get(uri);
I tried to find an answer but my problem is still there.
In my asynchronous upload function I return at the and the generated name of the image, which I want to use to make my database request.
This is my upload function:
Future<String> upload(File imageFile) async {
var stream =
new http.ByteStream(DelegatingStream.typed(imageFile.openRead()));
// get file length
var length = await imageFile.length();
var uri = Uri.parse("http://localhost:8080/upload");
var request = new http.MultipartRequest("POST", uri);
var multipartFile = new http.MultipartFile('file', stream, length,
filename: basename(imageFile.path));
request.files.add(multipartFile);
var response = await request.send();
print(response.statusCode);
var createdFileName = "";
response.stream.transform(utf8.decoder).listen((value) {
createdFileName = value;
print(createdFileName);
});
return createdFileName;
}
I call it like this:
List createdFileNames = [];
for (var e in imagefiles) {
createdFileNames.add(await upload(File(e)));
}
I don't know why, but the createdFileNames are ["",""], but the upload gives as result the right name. In debug mode I can see, that the loop does not wait until the upload has finished.
Do you have any suggestions?
Thank you very much!
response.stream.transform(utf8.decoder).listen((value) {
createdFileName = value;
print(createdFileName);
});
This part in your function is asynchronous, it uses a callback.
But you don't wait for it to finish in any form. You just continue to return the createdFileName, that by that time most likely has not been filled.
I don't know what your stream looks like, if you only need the first value, you could await that instead of listening:
createdFileName = await response.stream.transform(utf8.decoder).first;
Replace
response.stream.transform(utf8.decoder).listen((value) {
createdFileName = value;
print(createdFileName);
});
with
createdFileName=await response.stream.bytesToString();
change code
for (var e in imagefiles) {
upload(File(e)).then((value) => createdFileNames.add(value));
}
I've created a function which uploads an imageFile to Node.js server & AWS Bucket
If I call response.stream.transform(utf8.decoder).listen((value) async {} the value is equal to the CloudFront URL where my picture is stored
I'm trying to extract this URL from my Upload function to use it in my app but I can't find how :
Future<String> upload(File imageFile) async {
String url = '';
[...] // some code
// add file to multipart
request.files.add(multipartFile);
// send
var response = await request.send();
// listen for response
response.stream.transform(utf8.decoder).listen((value) async {
print(value); // prints the URL
url = value; // this value is the url where my picture is stored
// I'd like to use it outside this function
// I thought of returning it but I get an empty string
});
return url;
}
response.stream is a ByteStream. Rather than calling listen, call bytesToString - details here.
So you replace the whole transform section with:
return await response.stream.bytesToString();