Does anyone know how to get an argument pass by MethodChannel in windows?
Here is my code to send and receive data.
I need to get data value in string type
String data = "Some data";
await platform.invokeMethod("OpenViewer", {"data":data});
channel->SetMethodCallHandler([](const flutter::MethodCall<>& call, std::unique_ptr<flutter::MethodResult<>> result)
{
// check method name called from dart
if (call.method_name().compare("OpenViewer") == 0) {
}
else {
result->NotImplemented();
}
});
you could use something like below
if (method_call.method_name().compare("launch") == 0) {
std::string url = GetUrlArgument(method_call);
if (url.empty()) {
result->Error("argument_error", "No URL provided");
return;
}
std::optional<std::string> error = LaunchUrl(url);
if (error) {
result->Error("open_error", error.value());
return;
}
result->Success(EncodableValue(true));
For more read here from url_launcher
Related
In my app, a user can send a file to others in a group chat. First, the user records some audio using their mic. The file is then touched up using FFMPEG. Then, the file is uploaded to Firebase Cloud Storage and if this is successful, a record is written in Firebase Realtime Database.
I'm getting the error below when the user records a long audio file and then presses submit. It almost seems as though FFMPEG hasn't finished processing the file...but I thought I used my async/await correctly to make sure that this processing is finished before moving on?
##MyAppFile## saveMyAppFileToCloudStorage Error: 'package:firebase_storage/src/reference.dart': Failed assertion: line 127 pos 12: 'file.absolute.existsSync()': is not true.
Psuedo-code:
User records audio
Audio file is processed using FFMPEG and the new processed file is created on the user's phone
User hits submit, uploading the file to Cloud Storage and, if successful, writing a record to Realtime Database
Order of Functions After User Hits Submit:
msgInput.dart -> sendMyAppFile()
msgInput.dart -> prepareMyAppFileForSending()
msgInput.dart -> runFFMPEGHighLow()
message_dao.dart -> sendMyAppFile()
message_dao.dart -> saveMyAppFileToCloudStorage() //ERROR COMES FROM THIS FUNCTION
The Code:
//msgInput.dart
Future<void> sendMyAppFile() async {
if (sendableMyAppFileExists == 1) {
final MyAppFileReadyToBeSent = await prepareMyAppFileForSending();
if (MyAppFileReadyToBeSent == '1') {
messageDao.sendMyAppFile(MyAppFile, filepath, filename);
} else {
}
}
setState(() {
sendableMyAppFileExists = 0;
});
}
Future<String> prepareMyAppFileForSending() async {
if (sendableMyAppFileExists == 1) {
if (recordedMyAppFileFilterID == '1') {
await runFFMPEGHighLow('1');
return '1';
}
if (recordedMyAppFileFilterID == '2') {
await runFFMPEGHighLow('2');
return '1';
}
}
return '0';
}
Future<void> runFFMPEGHighLow(String filterID) async {
if (filterID != '1' && filterID != '2') {
return;
}
if (sendableMyAppFileExists == 1) {
if (filterID == '1') {
await FFmpegKit.executeAsync(/*...parms...*/);
setState(() {
currentMyAppFileFilename = currentMyAppFileFilename + '1.mp3';
});
}
if (filterID == '2') {
await FFmpegKit.executeAsync(/*...parms...*/);
setState(() {
currentMyAppFileFilename = currentMyAppFileFilename + '2.mp3';
});
}
}
}
//message_dao.dart
void sendMyAppFile(ChatData MyAppFile, String filepath, String filename) {
saveMyAppFileToCloudStorage(filepath, filename).then((value) {
if (value == true) {
saveMyAppFileToRTDB(MyAppFile);
}
});
}
Future<bool> saveMyAppFileToCloudStorage(String filepath, String filename) async {
//filepath: /data/user/0/com.example.MyApp/app_flutter/MyApp/MyAppAudioFiles/MyAppFiles/2d7af6ae-6361-4be5-8209-8498dd17d77d1.mp3
//filename: 2d7af6ae-6361-4be5-8209-8498dd17d77d1.mp3
_firebaseStoragePath = MyAppFileStorageDir + filename;
File file = File(filepath);
try {
await _firebaseStorage
.ref(_firebaseStoragePath)
.putFile(file);
return true;
} catch (e) {
print('##MyAppFile## saveMyAppFileToCloudStorage Error: ' + e.toString()); //ERROR COMES FROM THIS LINE
return false;
}
return true;
}
I assume you're using the package ffmpeg_kit_flutter.
First, why it's not working: execute and executeAsync return FFmpegSession objects. The run of FFmpeg doesn't need to be finished for these methods to complete. In fact, the returned session object has methods like getState to monitor whether the run of FFmpeg has completed.
A good way to fix this: The documentation for executeAsync has a hint for what to do here.
Note that this method returns immediately and does not wait the execution to complete. You must use an FFmpegSessionCompleteCallback if you want to be notified about the result.
You can set a completion callback by passing a function to executeAsync. Here's the full function signature from the docs:
Future<FFmpegSession> executeAsync(
String command,
[FFmpegSessionCompleteCallback? completeCallback = null,
LogCallback? logCallback = null,
StatisticsCallback? statisticsCallback = null]
)
FFmpegSessionCompleteCallback is just a function that accepts an FFmpegSession and returns nothing. You can provide your own.
void someCompletionFunction() {
setState(() {
currentMyAppFileFilename = currentMyAppFileFilename + '1.mp3';
});
}
await FFmpegKit.executeAsync(/*...parms...*/, someCompletionFunction);
Future vs callback: If you prefer to use Futures and async-await instead of callbacks, you'll need to create your own Future and update it in the callback. See Dart, how to create a future to return in your own functions? for an example.
I am new in flutter.
I am building an app to print on the ble label printer via Bluetooth.
I use flutter_blue library. I had successfully connected to the device and found the target characteristic. My problem is that when I call write() function of the characteristic printer show on display “waiting for data” and nothing is printed.
Could you please help me with the data format I need to put into the method?
I use utf8 encoded string as data.
Future<void> _print() async {
var serviceUuid = '0000ff00-0000-1000-8000-00805f9b34fb';
var characteristicsUuid = '0000ff02-0000-1000-8000-00805f9b34fb';
_services.forEach((service) {
if(service.uuid.toString().toLowerCase() == serviceUuid) {
printService = service;
for (var c in printService!.characteristics) {
if(c.uuid.toString().toLowerCase() == characteristicsUuid) {
var ZPL_TEST_LABEL = 'Hello WeChat!\r\n';
printCharacteristic = c;
writeData(printCharacteristic, ZPL_TEST_LABEL);
}
}
}});
}
Future<void> writeData(characteristic, data) async{
if (characteristic == null) return;
try {
var utf8Encoded = utf8.encode(data);
debugPrint(data.toString());
var result = await characteristic.write(utf8Encoded);
debugPrint(result.toString());
} catch (e) {
debugPrint(e.toString());
}
}
My first step is to print at least a string, could you pls help me?
I'm migrating my old version flutter code to latest version with null safety feature.
In a function call I am getting the error "The body might complete normally, causing 'null' to be returned, but the return type is a potentially non-nullable type". I have enclosed my code in try catch block and in catch block I added rethrow statement to prevent null exception.
This is my code.
Future<Map<String, dynamic>> fetchTimeline(http.Client client) async {
try {
print('INVOICE URL: ${globals.ursl.getURL(URLS.GETINVOICEURL)}');
Response response;
Dio dio = new Dio();
response = await dio.get(globals.ursl.getURL(URLS.GETINVOICEURL));
print('INVOICE GET RESPONSE: $response');
if (response.statusCode == 200) {
Map mapobject = (json.decode(response.toString()));
var succes = mapobject['success'];
if (succes == 1) {
if (mapobject['Invoice'][0]['address'] == null ||
mapobject['Invoice'][0]['address'] == '') {
address = '';
} else {
address = mapobject['Invoice'][0]['address'];
}
if (mapobject['Invoice'][0]['contact'] == null ||
mapobject['Invoice'][0]['contact'] == '')
phone = '';
else
phone = mapobject['Invoice'][0]['contact'];
if (mapobject['Invoice'][0]['restaurant_name'] == null ||
mapobject['Invoice'][0]['restaurant_name'] == '') {
name = ' ';
} else {
name = mapobject['Invoice'][0]['restaurant_name'];
}
logo = mapobject['Invoice'][0]['logo'];
globals.invoiceData = mapobject['Invoice'][0];
startTime();
return mapobject['Invoice'][0];
} else {
return {};
}
}
} catch (error) {
client.close();
print("CONNECTION CLOSED: $error");
rethrow;
}
}
I have added rethrow in catch block but still error is there.
Anyone there to help me out.
Thanks
It's a little hard to see with all the nested if statements, but you aren't returning a Map<String, dynamic> in every branch. This condition if (response.statusCode == 200) { ... } does not have a corresponding else branch, and so if the statusCode is some value other than 200 you are not returning anything (which means you are implicitly returning null in that case).
i have an http Get method like below
public async Task<Ricetta> GetRicettaByNome(string nome)
{
Ricetta exist = default(Ricetta);
var ExistRicetta = await appDbContext.Ricetta.FirstOrDefaultAsync(n => n.Nome == nome);
if(ExistRicetta != null)
{
exist = ExistRicetta;
return exist;
}
exist = null;
return exist;
}
It gets called by a controller like this:
[HttpGet("exist/{nome}")]
public async Task<ActionResult<Ricetta>> GetRicettaByNome(string nome)
{
try
{
if (string.IsNullOrEmpty(nome))
{
return BadRequest();
}
var result = await ricetteRepository.GetRicettaByNome(nome);
if (result != null)
return result;
return default(Ricetta);
}
catch (Exception)
{
return StatusCode(StatusCodes.Status500InternalServerError, "NON HAI INTERNET!");
}
}
But when i call my api to get the resposne by an httpclient like this:
public async Task<Ricetta> GetRicettaByNome(string nome)
{
return await httpClient.GetJsonAsync<Ricetta>($"api/Ricette/exist/{nome}");
}
i got this error:
the input does not contain any JSON tokens. Expected the input to start with a valid JSON token, when isFinalBlock is true. Path: $ | LineNumber: 0 | BytePositionInLine: 0.'
This is the expected result when you return null from your API. And default(Ricetta) is the same as null.
You will have to handle this some other way. GetJsonAsync<T>() is convenient shorthand when you know you will always have data. It is not the best option for dealing with null.
You can see (in dev tools) that the status code is 204 (No Content) for null. You can detect that or catch the error from GetJsonAsync.
Your error exist in your repository part where GetJsonAsync<>. You need to use HttpResponseMessage and check the content before Deserialize for example:
private async ValueTask<T> GetJsonAsync(string ur)
{
using HttpResponseMessage response = awiat _client.GetAsync(url);
//some method to validate response
ValidateResponse(response);
//then validate your content
var content = await ValidateContent(response).ReadAsStringAsync();
return JsonSerializer.Desrialize<T>(content, new JsonSerializerOptions() { PropertyNameCaseInsensitive = true });
}
//Here is the method that you need
private HttpContent ValidateContent(HttpResponseMessage response)
{
if(string.IsNullOrEmpty(response.Content?.ReadingAsString().Result))
{
return response.Content= new StringContent("null",Encoding.UTF8, MediaTypeNames.Application.Json);
}
else
{
return response.Content;
}
}
I am new to Unity i have created a Post Request from that i want to return the Authentication-Token Header and authorization header and some required json data here is my code
private IEnumerator BasketId()
{
string url = "http://hololens5.northeurope.cloudapp.azure.com/INTERSHOP/rest/WFS/inSPIRED-inTRONICS-Site/-/baskets/";
using (UnityWebRequest request = UnityWebRequest.Post(url, "Hello"))
{
yield return request.SendWebRequest();
string token = request.GetResponseHeader("Authentication-token");
if (request.isNetworkError || request.isHttpError)
{
Debug.Log(request.error);
}
else
{
string jsonResut = System.Text.Encoding.UTF8.GetString(request.downloadHandler.data);
obj = JsonConvert.DeserializeObject<BasketId>(jsonResut);
Debug.Log(obj.Uri);
Debug.Log("Authentication-Token: " + token);
yield return obj.Title;
yield return token;
}
}
}
so i could i return the values. Please help me.
Because Coroutine is not immediate (blocking) so you won't be able to return the response directly. What you need to do is to have an event or callback that will be called when your request completed.
Here is how you can achieve it by passing the callback as argument:
private IEnumerator GetBasketId(System.Action<string, BasketId> callback)
{
string url = "http://hololens5.northeurope.cloudapp.azure.com/INTERSHOP/rest/WFS/inSPIRED-inTRONICS-Site/-/baskets/";
using (UnityWebRequest request = UnityWebRequest.Post(url, "Hello"))
{
yield return request.SendWebRequest();
if (request.isNetworkError || request.isHttpError)
{
Debug.Log(request.error);
if (callback != null)
{
callback(null, null);
}
// callback?.Invoke(null, null); // for short
}
else
{
if (callback != null)
{
string token = request.GetResponseHeader("Authentication-token");
string jsonResut = System.Text.Encoding.UTF8.GetString(request.downloadHandler.data);
obj = JsonConvert.DeserializeObject<BasketId>(jsonResut);
if (callback != null)
{
callback(token, obj);
}
// callback?.Invoke(token, obj); // for short
}
}
}
}
so when you want to start the request simply call something like:
StartCoroutine(GetBasketId((token, basketId) =>
{
if (string.IsNullOrEmpty(token))
{
// Handle error
}
else
{
// Handle success
Debug.Log("Token: " + token);
Debug.Log(basketId.Title);
}
});