calling SignalR hub from WebAPI controller issues
Question
I cannot figure out how I can call into a SignalR hub from a WebAPI ApiController. I have put together a sample you can download here that simplifies the problem and demonstrates the issue.
- I created a new project from the ASP.NET MVC WebAPI template.
- I added a new SignalR Hub to the project called ChatHub.
- Added a HTML page that on load, connects to ChatHub, joins to a group and sends a message to that group. This works great.
- HTML page also has a button that when clicked will fire an ajax call to the ValuesController's post method. In the ValuesController's post method, I want to broadcast a message to all the connected clients of the group. I cannot get this to work.
I have a simple SignalR hub with just 2 methods.
[HubName("chat")]
public class ChatHub : Hub
{
public void Join(string room)
{
// NOTE: this is not persisted - ....
Groups.Add(Context.ConnectionId, room);
}
public void Send(string room, string message)
{
var msg = String.Format(
"{0}: {1}", Context.ConnectionId, message);
Clients.Group(room).newMessage(msg);
}
}
I created a very simple HTML page that connects to the Chat hub when the DOM is ready as shown here.
<html>
<head>
<title>Simple Chat</title>
<script src="Scripts/jquery-1.8.2.js" type="text/javascript"></script>
<script src="Scripts/jquery.signalR-1.0.0.js"></script>
<script src="signalr/hubs"></script>
<script type="text/javascript">
var chat;
//$(function () {
// connectToHubs();
//});
$(connectToHubs);
function connectToHubs() {
$.connection.hub.logging = true;
chat = $.connection.chat;
chat.client.newMessage = onNewMessage;
$.connection.hub.start({ transport: 'longPolling' }).done(function () {
chat.server.join("TestGroup").done(function () {
chat.server.send("TestGroup", "message from html");
});
});
$('#controller').click(postProficiencyUserAction);
}
var postProficiencyUserAction = function () {
//var token = $('[name=__RequestVerificationToken]').val();
var headers = {};
//headers["__RequestVerificationToken"] = token;
//var userAction = { createdOn: "2013-05-21T00:00:00", userId: "12345678-1234-1234-1234-000000000001", actionId: "12345678-1234-1234-1234-000000000003" };
$.ajax({
type: 'POST',
url: 'http://localhost:58755/api/values',
cache: false,
headers: headers,
contentType: 'application/json; charset=utf-8',
data: 'test',
dataType: "json",
success: function () {
},
error: function () {
}
});
};
function onNewMessage(message) {
// ... todo: validation !!!! :)
$('#messages').append('<li>' + message + '</li>');
};
</script>
</head>
<body>
<div>
<h2>Chat</h2>
<input type="button" id="controller" value="Controller Method" />
<div>
<h2>Message(s) Received</h2>
<ul id="messages"></ul>
</div>
</div>
</body>
</html>
Nothing fancy. Whenever the connected hub receives a new message, a new item is added to the unordered list. There is a button that makes an Ajax call into the ValuesController post method.
public class ValuesController : ApiController
{
// POST api/values
public void Post([FromBody]string value)
{
var hubContext = GlobalHost.ConnectionManager.GetHubContext<ChatHub>();
hubContext.Clients.Group("TestGroup").send("TestGroup", "Called from Controller");
}
The Hub call does not work. An error is not thrown, but, the message is never received. Putting a breakpoint in the "Send" method of the Hub does not work either. I feel like I am doing it right. Anyone help? Again, source code can be found here
2 answers
solution1
15 ACCPTED 2013-05-22 16:28:03
You are calling different methods on the client:
API controller
hubContext.Clients.Group("TestGroup").send("TestGroup", "Called from Controller");
Hub
Clients.Group(room).newMessage(msg);
The method you want to call is newMessage not send
chat.client.newMessage = onNewMessage;
solution2
0 2022-07-29 16:49:50
For ASP.NET Core you can now do the following:
[Route("some-route")]
public class MyController : ControllerBase
{
private readonly IHubContext<MyHub> _hubContext;
public MyController(IHubContext<MyHub> hubContext)
{
_hubContext = hubContext;
}
[HttpPost("message")]
public async Task<ActionResult> SendMessage(string message)
{
await _hubContext.Clients.All.SendAsync("Message", message);
return Ok();
}
}
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