Question

我知道当服务器发出invokation时，SignalR无法从客户端返回。在SignalR的github存储库中，我要求一个解决方法（https://github.com/aspnet/SignalR/issues/1329），他们建议我通过将它从客户端发送到服务器到集线器中的另一个方法来获得结果，因此使用TaskCompletionSource和一些连接元数据来捕获结果，但我仍然坚持如何做到这一点

控制器服务器：

[HttpPut("send/{message}")]
public async Task<IActionResult> SendMessage(string message)
{
    if (!ModelState.IsValid) return BadRequest(ModelState.Values);

    string connectionId = Request.Headers["connectionId"];
    await _chatHubContext.Clients.Client(connectionId).InvokeAsync("send");

    // Catch the call of MessageReceived and get the chat status

    return new OkObjectResult(new EmptyJsonResult() { Result = "OK" }); 

}

Hub服务器

public class ChatHub : Hub
{
    public Task MessageReceive(bool chatStatus)
    {
        // Tell controller that message is received
    }
}

Angular 4客户端

import { Component, Inject } from '@angular/core';
import { HubConnection } from '@aspnet/signalr-client';

@Component({
  selector: 'chat',
  templateUrl: './chat.component.html',
  styleUrls: ['./chat.component.css']
})
/** chat component*/
export class ChatComponent {
  hubConnection: HubConnection;
  chatStatus = false;

  /** chat ctor */
  constructor( @Inject('BASE_URL') private originUrl: string) {
    this.hubConnection = new HubConnection(`${this.originUrl}chat`);

    setInterval(() => {
      this.chatStatus = !this.chatStatus;
    },
      5000);

    this.hubConnection
      .start()
      .then(() => {
        this.hubConnection.on('send', (message: string) => {
          if (this.chatStatus) {
            //send message
          }
          this.hubConnection
            .invoke('messageReceived', this.chatStatus);
        });
      });

  }
}

正如您在此代码中看到的那样，我不知道在控制器方法和Hub方法中要做什么来知道调用MessageReceive方法并让他返回将其发送回控制器请求

Answer 1

＆＃34;稍微破解连接元数据和TaskCompletionSource，你也可能看起来很像一个返回值的方法调用。＆＃34; < / p>

控制器服务器：

注入HttpConnectionManager。

// using Microsoft.AspNetCore.Http.Connections.Internal;

public async Task<IActionResult> SendMessage(string message)
{
    string connectionId = Request.Headers["connectionId"];

    var chatStatus = await Send(connectionId, message);

    return new OkObjectResult(new { Result = "OK", ChatStatus = chatStatus });
}

private async Task<bool> Send(string connectionId, string message)
{
    var tcs = new TaskCompletionSource<bool>();

    _connectionManager.TryGetConnection(connectionId, out HttpConnectionContext connection);

    connection.Items.Add("tcs", tcs);

    await _chatHubContext.Clients.Client(connectionId).SendAsync("send", message);

    var chatStatus = await tcs.Task;

    connection.Items.Remove("tcs");

    return chatStatus;
}

中心服务器：

public Task MessageReceived(bool chatStatus)
{
    Context.Items.TryGetValue("tcs", out object obj);

    var tcs = (TaskCompletionSource<bool>)obj;

    tcs.SetResult(chatStatus);

    return Task.CompletedTask;
}

Angular 4客户：

// No change

SignalR解决方法从服务器获取客户端数据

控制器服务器：

Hub服务器

Angular 4客户端

1 个答案: