What is right usage or better way of under the two methods?
Method one
Future<bool> signout()async{
try {
await _googleSignIn.disconnect();
await _googleSignIn.signOut();
return true;
} catch (e) {
return false;
}
}
Method two
Future<bool> signout()async{
try {
await _googleSignIn.signOut();
return true;
} catch (e) {
return false;
}
}
Flutter Package Google_Sign_In
Difference between signout and disconnect is explain here :-
https://developers.google.com/identity/sign-in/android/disconnect
As my perspective this was better I use google signing my 8 apps and all are live on both stores I use this method everywhere
Future<bool> signout()async{
try {
await _googleSignIn.signOut();
return true;
} catch (e) {
return false;
}
}
Related
i am making a app. And i want to check my server state every minite and give user information
about the server. How do i do it. is stream good for it. Can some provide me a code for that.
just follow this guide
suppose your bool return value function is
Future<bool> isGpsOn() async {
return await Geolocator().isLocationServiceEnabled();
}
and this is create stream from bool value
Stream futureToStream(fn, defaultValue, Duration duration) async* {
var result;
while (true) {
try {
result = await fn();
}
catch (error) {
result = defaultValue;
}
finally {
yield result;
}
await Future.delayed(duration);
}
}
final gpsStatusStream = futureToStream(isGpsOn, false, Duration(seconds: 5));
gpsStatusStream.listen((enabled) {
print(enabled ? 'enabled' : 'disabled');
});
Use asyncMap
Stream<String> checkConnectionStream() async* {
yield* Stream.periodic(Duration(seconds: 1), (_) {
return //your function
}).asyncMap((event) async => await event);
}
For image_picker MainActivity destruction I wanted to use other plugin to pick image. And I found wechat_camera_picker as an alternative. But there was a problem while capturing the image. The captured image saved on Local Storage after selecting the image. Here is my code.
Future<File> getImageByCamera(BuildContext context) async {
try{
final AssetEntity result = await CameraPicker.pickFromCamera(
context,
pickerConfig: CameraPickerConfig(
shouldDeletePreviewFile: true,
enableRecording: false,
textDelegate: EnglishCameraPickerTextDelegate(),
),
);
if(result != null){
File pickedFile = await result.file;
pickedFile = await compressFile(pickedFile);
return pickedFile;
}else{
return null;
}
}catch(error){
print(error);
return null;
}
}
Does anyone have any solution of this problem?
you can use the below function to delete the locally stored file.
Future<bool> deleteFile(File pickedFile) async {
try {
await pickedFile.delete();
return true;
} catch (e) {
return false;
}
}
You can check the Delete Function Documation for referenece.
I upgraded Flutter from version 2.0.2 to version 2.2.2 and now the custom exceptions that are thrown from a Future function are not being catch.
For example, I got this Future function, where I call another Future that does a server request and returns back the response or throws a custom exception (ApiException) in case of error:
static Future<bool> signUpCustomerRequest(Map<String, dynamic> params) async {
try {
// Here we call this Future function that will do a request to server API.
dynamic _response = await _provider.signUpCustomer(params);
if (_response != null) {
updateUserData(_response);
return true;
}
return false;
} on ApiException catch(ae) {
// This custom exception is not being catch
ae.printDetails();
rethrow;
} catch(e) {
// This catch is working and the print below shows that e is Instance of 'ApiException'
print("ERROR signUpCustomerRequest: $e");
rethrow;
} finally {
}
}
And this is the Future function that does the request to server and throws the ApiException:
Future<User?> signUpCustomer(Map<String, dynamic> params) async {
// POST request to server
var _response = await _requestPOST(
needsAuth: false,
path: routes["signup_client"],
formData: params,
);
// Here we check the response...
var _rc = _response["rc"];
switch(_rc) {
case 0:
if (_response["data"] != null) {
User user = User.fromJson(_response["data"]["user"]);
return user;
}
return null;
default:
print("here default: $_rc");
// And here we have the throw of the custom exception (ApiException)
throw ApiException(getRCMessage(_rc), _rc);
}
}
Before upgrading to Flutter 2.2.2 the catch of custom exceptions worked perfectly. Did something change on this Flutter version? Am I doing something wrong?
Thanks!
I was able to reproduce your bug with the following code:
class ApiException implements Exception {
void printDetails() {
print("ApiException was caught");
}
}
Future<void> doSomething() async {
await Future.delayed(Duration(seconds: 1));
throw ApiException();
}
void main() async {
try {
await doSomething();
} on ApiException catch (ae) {
ae.printDetails();
} catch (e) {
print("Uncaught error: $e"); // This line is printed
}
}
There's an open issue on the dart sdk, which I think might be related, though I'm not sure: https://github.com/dart-lang/sdk/issues/45952.
In any case, I was able to correct the error by returning a Future.error, instead of throwing the error directly:
class ApiException implements Exception {
void printDetails() {
print("ApiException was caught"); // This line is printed
}
}
Future<void> doSomething() async {
await Future.delayed(Duration(seconds: 1));
return Future.error(ApiException());
}
void main() async {
try {
await doSomething();
} on ApiException catch (ae) {
ae.printDetails();
} catch (e) {
print("Uncaught error: $e");
}
}
I'm new to Flutter & Dart, trying to complete my first app.
I can't catch (with try-catch block) http.get SocketException (which happens when you call API and WiFi turned off)
I tried everything on the internet without luck, I even tried (Dio) package to catch this exception, but no success.
How to reproduce: use bottom code...turn off phone's WiFi...call API...now the app crashes with (SocketException) in your IDE.
Image: https://imgur.com/bA0rKEN
here is my simple code (updated)
RaisedButton(
child: Text("Call API"),
onPressed: () async {
try {
http.Response response = await getLoginResponse();
//do something with response
print(response.body);
} catch (e) {
print("Button onPressed Error: " + e.toString());
}
},
)
//---------------------------------------------------------------
Future<http.Response> getLoginResponse() {
return http.get(loginUrl).timeout(Duration(seconds: 10))
.then((response) {
return response;
}, onError: (e) {
print("onError: " + e.toString());
}).catchError((err) {
print("catchError: " + err.toString());
return null;
});
}
You can catch several types of errors and handle each one separately
Example:
import 'dart:io' as Io;
http.Client client = http.Client();
try {
response = await client.get(url).timeout(new Duration(seconds: 10));
} on Io.SocketException catch (_) {
throw Exception('Not connected. Failed to load data');
} on TimeoutException catch (_) {
throw Exception('Not connected. TimeOut Exception');
} catch (e) {
// Default error handling;
}
if you want to get catch in RaisedButton's try-catch block, instead of return null in getLoginInfo() methods, you must return an Exception like this:
Future<List<LoginObject>> getLoginInfo() async {
try {
List<LoginObject> loginObjectList = List<LoginObject>();
http.Response loginResponse =
await http.get(loginUrl).timeout(Duration(seconds: 10));
if (loginResponse.statusCode == 200) {
loginObjectList = loginObjectFromJson(loginResponse.body);
return loginObjectList;
} else {
throw Exception('Authentication Error');
}
} catch (e) {
print("Error: " + e.toString());
return throw Exception('Connection Error');;
}
}
Note: If you want to handle each one of error response, you can create an custom ErrorModelClass and handle error state with it and finally return your ErrorModelClass.
catch (error) {
print(error);
throw error is HttpResponseError ? error : HttpResponseError(0,"error connection");
HttpResponseError is my custom model class.
Using the code from the package I was unable to catch the exception. Note that I would like to catch this specific exception.
// from https://pub.dev/packages/url_launcher
_launchURL() async {
const url = 'myscheme://myurl';
if (await canLaunch(url)) {
await launch(url);
} else {
throw 'Could not launch $url';
}
}
// my code
try {
_launchURL();
}
catch (e)
{
// although the exception occurs, this never happens, and I would rather catch the exact canLaunch exception
}
I would try to put the try catch statement inside the function. I believe what is happening is that the try/catch statement is only applying for the function call and although it is async I dont believe that it actually tries and returns exeptions.
So the solution would look somethink like this:
_launchURL() async {
try{
const url = 'myscheme://myurl';
if (await canLaunch(url)) {
await launch(url);
} else {
throw 'Could not launch $url';
}
}
catch(e){
//debug e
}
}
// my code
launchURL();
You can use .then() for business logic.
For me, it is used to check if the app can be opened on the device.
Can be solution below,
--> url_launcher: ^6.0.2
--> https://pub.dev/packages/url_launcher
launch(appLink).then(
(bool isLaunch) {
print('isLaunch: $isLaunch');
if (isLaunch) {
// Launch Success
} else {
// Launch Fail
}
},
onError: (e) {
print('onError: $e');
},
).catchError(
(ex) => print('catchError: $ex'),
);
Work for me.
Future<void> _launch(String url) async {
await canLaunch(url)
? await launch(url)
: throw 'Could not launch $url';
}