SignalR call from controller

问题

I'm needing to pass strings from my controller to a signalR hub and have it render on my page. I've followed along with the chat tutorial found at: https://docs.microsoft.com/en-us/aspnet/core/tutorials/signalr?view=aspnetcore-2.2&tabs=visual-studio

The next step from the chat tutorial is breaking it out message call to my controller like so:

[HttpPost]
public async Task<IActionResult> Upload(string engineType)
{
    try
    {
        var message = "File Upload Failed";
        
        await _errorHub.Clients.All.SendAsync("SendMessage", message);
        return Ok();
    }
    catch (Exception ex)
    {
        Log.Error("File Upload failed: " + ex);
        return NotFound();
    }
}

I have injected my hub into my controller, which is how I'm able to access the Clients.All... call.

My hub is only different from the tutorial in that I removed the user parameter:

 public class UserErrorHub : Hub
{
    public async Task SendMessage( string message)
    {
        await Clients.All.SendAsync("ReceiveMessage", message);
    }
}

Finally, in my javascript, I have the following SignalR set up:

var connection = new signalR.HubConnectionBuilder().withUrl("myURL").build();

connection.on("ReceiveMessage", function (user, message) {
    console.log("ReceiveMessage");
    var msg = message.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;");
    var encodedMsg = user + " says " + msg;
    var li = document.createElement("li");
    li.textContent = encodedMsg;
    document.getElementById("messagesList").appendChild(li);
});

When I run my project, the console output informs me that I hub is set up fine like so:

[2020-09-03T09:45:23.384Z] Information: Normalizing '/Signalr' to 'https://localhost:44336/Signalr'.

However, when I trigger my Upload method, nothing gets sent to my hub. What is it I'm doing wrong?

回答1:

await _errorHub.Clients.All.SendAsync("SendMessage", message);

"SendMessage" should be "ReceiveMessage"

回答2:

You are calling _errorHub.Clients.All.SendAsync("SendMessage", message) in your controller instead of _errorHub.SendMessage(message). This means you're controller directly is invoking SendMessage on your clients, but you're client is only listening to ReceiveMessage.

So, you'll want to call _errorHub.SendMessage(message) in your controller, which in turn calls Clients.All.SendAsync("ReceiveMessage", message) which will trigger your clients ReceiveMessage method

来源：https://stackoverflow.com/questions/63721149/signalr-call-from-controller

标签

javascript

model-view-controller

.net-core

signalr