I have been dealing this error for a long time. I just want to make signalr to listen my 2 method. When i comment the (this) methods it works perfectly.
But it doesnt work. Can someone help me? Sometimes i can get the value but then it gets me the error like below the image. I researched some pages but cant find any answer actually.
Vuejs
const hubConnection = new signalR.HubConnectionBuilder()
.configureLogging(signalR.LogLevel.Debug)
.withUrl("http://localhost:7002/ChatHub", {
skipNegotiation: true,
transport: signalR.HttpTransportType.WebSockets,
})
.build();
hubConnection.start();
this.connectionId = hubConnection.connectionId;
this.connection = hubConnection;
hubConnection.on("UserConnected",(users) => console.log(users));(this)
hubConnection.on(categoryId, (all) => {
all = JSON.parse(all);
this.userMessage = {
id: all.Id,
text: all.Text,
userId:all.UserId,
userName:all.UserName,
categoryName: all.CategoryName,
createdOn: all.CreatedOn,
};
this.messages.push(this.userMessage);
console.log(this.userMessages);
});
},
using Microsoft.AspNetCore.SignalR;
using System.Text;
using Microsoft.AspNetCore.SignalR.Client;
using Microsoft.AspNetCore.Http;
using System;
using System.Web;
using System.Net.Http.Headers;
using System.Linq;
using System.IdentityModel.Tokens.Jwt;
using System.IdentityModel.Tokens;
using System.Collections.Generic;
using System.Threading.Tasks;
using Message.Dal.Concrete;
using Message.Dal.Abstract;
using Message.Dal.Model;
using Microsoft.Extensions.Configuration;
namespace Message.Dal.SignalRHub
{
public class ChatHub : Hub
{
private readonly IHubContext<ChatHub> _chatHub;
private readonly IHttpContextAccessor _httpContextAccessor;
private readonly IElasticRepository<OnlineUserModel> _elasticRepository;
private readonly string _indexName;
public ChatHub(IHubContext<ChatHub> chatHub,IElasticRepository<OnlineUserModel> elasticRepository,IConfiguration configuration)
{
_chatHub = chatHub;
_httpContextAccessor = new HttpContextAccessor();
_elasticRepository = elasticRepository;
_indexName = configuration["elasticsearchserver:User"].ToString();
}
public async Task SendMessage(Guid categoryId,string message)
{
await _chatHub.Clients.All.SendAsync(categoryId.ToString(),message);
}
public override Task OnConnectedAsync()
{
var token = string.Empty;
var httpContext = _httpContextAccessor.HttpContext.Request.Cookies;
var onlineUserModel = new OnlineUserModel();
onlineUserModel.Id = Context.ConnectionId;
if(!httpContext.Any())
{
return Task.CompletedTask;
}
token = httpContext.Where(x=> x.Key == "CodeChatBackend").FirstOrDefault().Value;
if(AuthenticationHeaderValue.TryParse(token,out var headerVal))
{
var handler = new JwtSecurityTokenHandler();
var val = handler.ReadJwtToken(headerVal.ToString());
onlineUserModel.UserName = val.Claims.FirstOrDefault(x => x.Type == "Name").Value;
}
var checkOnlineUser = _elasticRepository.GetUserAsync(onlineUserModel.UserName,_indexName);
if(checkOnlineUser.Result == null)
{
_elasticRepository.CreateUserAsync(onlineUserModel.Id,onlineUserModel,_indexName);
}
var getOnlineUser = _elasticRepository.GetAllAsync(_indexName);
_chatHub.Clients.All.SendAsync("UserConnected",getOnlineUser);(this)
base.OnConnectedAsync();
return Task.CompletedTask;
}
public override Task OnDisconnectedAsync(Exception exception)
{
var httpContext = _httpContextAccessor.HttpContext.Request.Cookies;
var token = string.Empty;
var result = _elasticRepository.DeleteUserAsync(Context.ConnectionId,_indexName);
var getOnlineUser = _elasticRepository.GetAllAsync(_indexName);
_chatHub.Clients.All.SendAsync("UserConnected",getOnlineUser);(this)
base.OnDisconnectedAsync(exception);
return Task.CompletedTask;
}
}
}
When i delete the onconnectedasync client method. It works perfectly. Am i missing something?
I fixed it! My mistake totally. I was trying to make one hub to connect different methods. To fix this: Create second hub class and configure your startup, then call hub method with a new connection.
Related
I use signalR in my project. It works fine. In a part on my project, I need to use instant notification when a delete button is clicked. The button is in jQuery datatable. I used the following code:
var connection = new signalR.HubConnectionBuilder().withUrl("/signalRServer").withAutomaticReconnect().build();
connection.start();
function DeleteData(pmId, mainFileName, fileName) {
if (confirm("Are you sure")) {
connection.invoke("PmPageUpdate", pmId).catch(function(err){
return console.error(err);
});
Delete(pmId, mainFileName, fileName);
} else {
return false;
}
}
When I debug, the hub method is not called. Console shows the following error:
PmManagement:692 Error: Failed to invoke 'PmPageUpdate' due to an
error on the server.
at H. (signalr.js:1:13973)
at L.I (signalr.js:1:14804)
at X.L.connection.onreceive (signalr.js:1:10649)
at WebSocket.r.onmessage (signalr.js:1:27565)
How can I fix this?
Update:
The followings are codes I've written for the hub. Some methods that are not related to this question has been ignored.
Hub:
private readonly IUserRepository _userRepository;
private readonly ICostCenterRepository _costcenterRepository;
private readonly IHttpContextAccessor _httpContext;
private readonly INotificationRepository _notificationRepository;
private readonly IMessageRepository _messageRepository;
private readonly IPmRepository _pmRepository;
public MessageHub(IUserRepository userRepository, ICostCenterRepository costcenterRepository, IHttpContextAccessor httpContext,
INotificationRepository notificationRepository, IMessageRepository messageRepository, IPmRepository pmRepository)
{
_userRepository = userRepository;
_costcenterRepository = costcenterRepository;
_httpContext = httpContext;
_notificationRepository = notificationRepository;
_messageRepository = messageRepository;
_pmRepository = pmRepository;
}
//define a dictionary to store the userid.
private static Dictionary<string, List<string>> NtoIdMappingTable = new Dictionary<string, List<string>>();
public Task JoinNotificationGroup(string groupName)
{
return Groups.AddToGroupAsync(Context.ConnectionId, groupName);
}
public Task LeaveNotificationGroup(string groupName)
{
return Groups.RemoveFromGroupAsync(Context.ConnectionId, groupName);
}
public override async Task OnConnectedAsync()
{
var username = Context.User.Identity.Name;
var userId = Context.UserIdentifier;
List<string> userIds;
//store the userid to the list.
if (!NtoIdMappingTable.TryGetValue(username, out userIds))
{
userIds = new List<string>();
userIds.Add(userId);
NtoIdMappingTable.Add(username, userIds);
}
else
{
userIds.Add(userId);
}
await base.OnConnectedAsync();
}
public override async Task OnDisconnectedAsync(Exception exception)
{
var username = Context.User.Identity.Name;
//remove userid from the List
if (NtoIdMappingTable.ContainsKey(username))
{
NtoIdMappingTable.Remove(username);
}
await base.OnDisconnectedAsync(exception);
}
string username = _userRepository.GetUsernameByCostCenter(pmId).ToString();
var userId = NtoIdMappingTable.GetValueOrDefault(username);
await Clients.User(userId.ToString()).SendAsync("SignalReceiver");
}
I am having difficulty running JS in CefSharp due to the command running straight after each other. Basically, I need a wait command to await the page to load after executing the last script.
Hence it would be:
await Browser.ExecuteScriptAsync(script1);
Browser.WaitForLoad();
Task<JavascriptResponse> test = await Browser.EvaluateScriptAsync(script2);
I have found a few resources but I'm only new to programming so I'm finding it a bit difficult to work out how I can do what I want.
using System.Threading;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using CefSharp;
using CefSharp.Wpf;
namespace WpfApp2
{
public partial class MainWindow : Window
{
private string MessagesInbox;
public MainWindow()
{
InitializeComponent();
}
private void Browser_Loaded(object sender, RoutedEventArgs e)
{
Browser.LoadingStateChanged += async (Sender, args) => {if (args.IsLoading == false)
{
await Browser.EvaluateScriptAsync(#"document.getElementById('User').value = 'test'; document.getElementById('Password').value = 'password'; document.getElementById('LoginButton').click();");
}};
Task<JavascriptResponse> test = Browser.EvaluateScriptAsPromiseAsync(#"return new Promise(function(resolve, reject) { setTimeout(resolve.bind(null, { var test = ''; document.querySelectorAll('.MasterAction').forEach(el => test += el.children[3].children[0].href + ', ')}), 2000);");
MessagesInbox = test.Result.ToString();
MessageBox.Show(MessagesInbox);
}
}
}
You should also check the IsLoading for your second method, you can use a bool to track if you are already logged in, and use the second method inside that function aswell like this:
public bool loggedIn = false;
private void Browser_Loaded(object sender, EventArgs e)
{
Browser.LoadingStateChanged += async (Sender, args) =>
{
if (args.IsLoading == false)
{
if (!loggedIn)
{
await Browser.EvaluateScriptAsync(#"document.getElementById('User').value = 'test'; document.getElementById('Password').value = 'password'; document.getElementById('LoginButton').click();")
.ContinueWith(x =>
{
var response = x.Result;
System.Diagnostics.Debug.WriteLine(response.Result);
if (response.Result == null)
{
System.Diagnostics.Debug.WriteLine("should be changed to true");
loggedIn = true;
}
});
}
else
{
JavascriptResponse test = await Browser.EvaluateScriptAsync(#"var test = ''; document.querySelectorAll('.MasterAction').forEach(el => test += el.children[3].children[0].href + ', ');test.substr(0,test.length-2)");
MessagesInbox = test.Result.ToString();
System.Diagnostics.Debug.WriteLine(MessagesInbox);
}
}
};
}
I have tried to execute JavaScript on an external url (ie: http://facebook.com) using WebView from Visual Studio Mac 2019, and so far no results.
To do so, I have tried to follow along with the official tutorial here https://learn.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/custom-renderer/hybridwebview, and also tried a simpler one here: https://xamarinhelp.com/xamarin-forms-webview-executing-javascript/
Here is what I did with explanations:
On my shared folder, I created an HybridWebView class with the following code:
public class HybridWebView : WebView
{
Action<string> action;
public static readonly BindableProperty UriProperty = BindableProperty.Create(
propertyName: "Uri",
returnType: typeof(Func<string, Task<string>>),
declaringType: typeof(HybridWebView),
defaultValue: default(string));
public string Uri
{
get => (string)GetValue(UriProperty);
set
{
SetValue(UriProperty, value);
}
}
public void RegisterAction(Action<string> callback)
{
action = callback;
}
public void Cleanup()
{
action = null;
}
public void InvokeAction(string data)
{
if (action == null || data == null)
{
return;
}
action.Invoke(data);
}
public Func<string, Task<string>> ExecuteJavascript
{
get { return (Func<string, Task<string>>)GetValue(UriProperty); }
set { SetValue(UriProperty, value); }
}
}
From The macOS project which I use to test my cross-platform app, I tried the following custom renderer:
public class HybridWebViewRenderer : ViewRenderer<HybridWebView, WKWebView>
{
protected override void OnElementChanged(ElementChangedEventArgs<HybridWebView> e)
{
base.OnElementChanged(e);
var webView = e.NewElement as HybridWebView;
if (webView != null)
{
Control.LoadRequest(new NSUrlRequest(new NSUrl(Element.ExecuteJavascript.ToString())));
}
}
}
To note that the following part wouldn't work:
var webView = e.NewElement as HybridWebView;
if (webView != null)
webView.ExecuteJavascript = (js) =>
{
return Task.FromResult(this.ExecuteJavascript(js)); // issue at ExecuteJavascript with following error ('HybridWebViewRenderer' does not contain a definition for 'ExecuteJavascript' ), hence replaced by Control.LoadRequest ...
};
From my ViewModel, I did the following:
public Func<string, Task<string>> EvaluateJavascript { get; set; }
public async Task OnConnectTapped()
{
Console.WriteLine("on connect tapped");
// passing the url onto a connection service
var hybridWebView = new HybridWebView
{
Uri = "https://facebook.com/"
};
//hybridWebView.InvokeAction("document.getElementById('td');");
//var result = await hybridWebView.RegisterAction(data => DisplayAlert("Alert", "Hello " + data, "OK"));
var result = await hybridWebView.ExecuteJavascript("document.cookie;");
Console.WriteLine("result is {0}", result);
}
Here is the error when trying to execute my code:
System.NullReferenceException: Object reference not set to an instance of an object
at MyApp.ViewModel.MainModel.OnConnectTapped () [0x00031] in .../../././/ViewModel/MainModel.cs:451
at .......<.ctor>g__c5|48_9 () [0x0001f] in /../../../.cs:143
at System.Runtime.CompilerServices.AsyncMethodBuilderCore+<>c.<ThrowAsync>b__7_0 (System.Object state) [0x00000] in /Users/builder/jenkins/workspace/xamarin-macios/xamarin-macios/external/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/AsyncMethodBuilder.cs:1021
at Foundation.NSAsyncSynchronizationContextDispatcher.Apply () [0x00002] in /Library/Frameworks/Xamarin.Mac.framework/Versions/6.6.0.12/src/Xamarin.Mac/Foundation/NSAction.cs:178
at at (wrapper managed-to-native) AppKit.NSApplication.NSApplicationMain(int,string[])
at AppKit.NSApplication.Main (System.String[] args) [0x00040] in /Library/Frameworks/Xamarin.Mac.framework/Versions/6.6.0.12/src/Xamarin.Mac/AppKit/NSApplication.cs:100
at redacted.macOS.MainClass.Main (System.String[] args) [0x00017] in /Users/dom-bruise/Projects/redacted/redacted.macOS/Main.cs:11
For me, it could either be because I can't execute external pages, or the part where I replaced by the following messing up my attempt.
if (webView != null)
{
Control.LoadRequest(new NSUrlRequest(new NSUrl(Element.ExecuteJavascript.ToString())));
}
My main goal here is to have my app execute JavaScript underneath the hood on pages using WebView, and fill in forms automatically calling back C# from my app.
I've created a plugin which connects and subscribes to pusher channel successfully via NativeScript using this Java plugin,
now I'm trying to create an eventListener to get events in Nativescript,
this is my Java plugin:
public class PusherAndroid {
public void connectToPusher(String app_key, String channel_name, String event_name) {
PusherOptions options = new PusherOptions().setCluster("eu");
Pusher pusher = new Pusher(app_key, options);
pusher.connect(new ConnectionEventListener() {
#Override
public void onConnectionStateChange(ConnectionStateChange change) {
System.out.println("State changed to " + change.getCurrentState() +
" from " + change.getPreviousState());
}
#Override
public void onError(String message, String code, Exception e) {
System.out.println("There was a problem connecting!");
}
}, ConnectionState.ALL);
Channel channel = pusher.subscribe(channel_name);
channel.bind(event_name, new SubscriptionEventListener() {
#Override
public void onEvent(PusherEvent event) {
System.out.println("Received event with data: " + event.toString());
}
});
}
}
and this is my module:
module.exports = {
connect:function(app_key, channel_name, event_name) {
var psh = new com.pxb.pusherandroid.PusherAndroid();
psh.connectToPusher(app_key, channel_name, event_name);
var EventListener;
function initializeEventListener() {
if (EventListener) {
return;
}
EventListener = com.pxb.pusherandroid.PusherAndroid.extend({
interfaces: [com.pusher.client.channel.SubscriptionEventListener],
onEvent: event => {
console.log(event);
}
});
}
initializeEventListener();
<HERE I NEED MY CHANNEL>.bind(event_name, new EventListener());
}
};
Now, how can I get this channel in Javascript, to use it as my defined connected channel and bind eventListener to it?
Channel channel = pusher.subscribe(channel_name);
thank you
I dont really know how NativeScript works, but couldn't you just searialize your Channel to a json string, store it in a global variable on your PusherAndroid class and then access and desearialize it on your module?
thanks to #Manoj, there's no need to code in Java and try to use them in Javascript,
we can directly use Java classes and methods with Javascript,
there's really not enough reference for this.
here is my module after deleting all java code and just calling the classes and methods from pusher-java-library directly:
module.exports = {
connect:function(app_key, channel_name, event_name) {
PusherOptions = com.pusher.client.PusherOptions;
Pusher = com.pusher.client.Pusher;
Channel = com.pusher.client.channel.Channel;
SubscriptionEventListener = com.pusher.client.channel.SubscriptionEventListener;
PusherEvent = com.pusher.client.channel.PusherEvent;
var options = new PusherOptions().setCluster("eu");
var pusher = new Pusher(app_key, options);
pusher.connect();
var channel = new Channel(pusher.subscribe(channel_name));
}
};
now going to add my eventlistener with Javascript <3
I am using ServiceStack.Client to consume, the data pushed by my server(which is an aspx page).
Below is the code which i use to consume the data using ServiceStack Client:
using System;
using System.Net.Sockets;
using System.Net;
using System.Security.Cryptography;
using System.Threading;
using ServiceStack;
using System.Collections.Generic;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
ServerEventConnect connectMsg = null;
var msgs = new List<ServerEventMessage>();
var commands = new List<ServerEventMessage>();
var errors = new List<Exception>();
var client = new ServerEventsClient("https://testing.leadsquared.com/ReferralCampaign/Demo")
{
OnConnect = e => PrintMsg(e),
OnCommand = e => PrintCmdMsg(e),
OnMessage = e => PrintCmMsg(e),
OnException = e => PrintExMsg(e)
}.Start();
Console.Read();
}
private static void PrintCmMsg(ServerEventMessage e)
{
if (e != null)
{
PrintMsg(e.Data);
}
}
private static void PrintExMsg(Exception e)
{
if (e != null)
{
PrintMsg(e.Message);
}
}
private static void PrintCmdMsg(ServerEventMessage e)
{
if (e != null)
{
PrintMsg(e.Data);
}
}
private static void PrintMsg(ServerEventConnect e)
{
if (e!=null)
{
PrintMsg(e.Data);
}
}
private static void PrintMsg(string x)
{
Console.WriteLine(x);
}
}
}
When I run my code , the client does print any message on the console.
The ConnectionDisplayName property is "(not connected)".
If i subscribe to the same URL using javascript EventSource, i get the notifications.
My requirement is that I would want to consume the data by my server in C#.
How can I achieve this?
Firstly the url needs to be the BaseUri where ServiceStack is hosted, i.e. the same url used in JavaScript ServerEvents Client, e.g:
var client = new ServerEventsClient(BaseUrl).Start();
It's not clear if /ReferralCampaign/Demo is the BaseUri or not.
You will also want to call Connect() to wait for the client to make a connection, e.g:
await client.Connect();
Then to see message events you'll need to call a ServiceStack Service that publishes a Notify* Event on IServerEvents API which you can use with a separate JsonServiceClient or the ServiceClient available in ServerEventsClient, e.g:
client.ServiceClient.Post(new PostRawToChannel {
From = client.SubscriptionId,
Message = "Test Message",
Channel = channel ?? "*",
Selector = "cmd.announce",
});
This is an example calling the Chat PostRawToChannel ServiceStack Service:
public class ServerEventsServices : Service
{
public IServerEvents ServerEvents { get; set; }
public void Any(PostRawToChannel request)
{
// Ensure the subscription sending this notification is still active
var sub = ServerEvents.GetSubscriptionInfo(request.From);
if (sub == null)
throw HttpError.NotFound("Subscription {0} does not exist".Fmt(request.From));
// Check to see if this is a private message to a specific user
if (request.ToUserId != null)
{
// Only notify that specific user
ServerEvents.NotifyUserId(request.ToUserId, request.Selector, request.Message);
}
else
{
// Notify everyone in the channel for public messages
ServerEvents.NotifyChannel(request.Channel, request.Selector, request.Message);
}
}
}
I also recommend looking at the C# ServerEventTests for complete stand-alone examples using C# ServerEventClient.