Azure SignalR Service无服务器Hub问题咨询：连接事件与消息发送

问题1、2：OnConnected/OnDisconnected 无日志输出 #

你的SignalRTrigger属性缺少必要配置，无服务器模式下必须明确指定Hub名称和触发事件类型。修改代码如下：

[FunctionName(nameof(OnConnected))]
public async Task OnConnected(
    [SignalRTrigger("MyHub", "connected")] InvocationContext invocationContext, 
    ILogger logger)
{
    logger.LogInformation($"{invocationContext.ConnectionId} has connected");
}

[FunctionName(nameof(OnDisconnected))]
public async Task OnDisconnected(
    [SignalRTrigger("MyHub", "disconnected")] InvocationContext invocationContext, 
    ILogger logger)
{
    logger.LogInformation($"{invocationContext.ConnectionId} has disconnected");
}

另外检查Negotiate方法：当前返回Negotiate()（ServerlessHub默认方法），但你已注入SignalRConnectionInfo，建议直接返回该对象确保连接信息正确传递：

return new OkObjectResult(connectionInfo);

问题3：向指定客户端发送直接消息 #

使用Azure Functions的SignalR输出绑定，在函数中注入IAsyncCollector<SignalRMessage>，指定目标ConnectionId发送消息：

[FunctionName("SendToSpecificClient")]
public async Task SendToSpecificClient(
    [HttpTrigger(AuthorizationLevel.Anonymous, "post")] ClientMessage req,
    [SignalR(HubName = "MyHub")] IAsyncCollector<SignalRMessage> signalRMessages,
    ILogger log)
{
    await signalRMessages.AddAsync(new SignalRMessage
    {
        Target = "OrderEvent", // 客户端监听的方法名
        ConnectionId = req.TargetConnectionId, // 目标客户端的ConnectionId
        Arguments = new[] { req.Order, req.Msg } // 传递的参数
    });
}

// 定义接收请求的模型
public class ClientMessage
{
    public string TargetConnectionId { get; set; }
    public string Order { get; set; }
    public string Msg { get; set; }
}

问题4：向群组发送消息 #

步骤1：让客户端加入群组 #

可以在OnConnected事件中自动将客户端加入指定群组，或提供单独函数让客户端主动调用加入：

// 方式1：OnConnected时自动加入群组
[FunctionName(nameof(OnConnected))]
public async Task OnConnected(
    [SignalRTrigger("MyHub", "connected")] InvocationContext invocationContext,
    [SignalR(HubName = "MyHub")] IAsyncCollector<SignalRGroupAction> signalRGroupActions,
    ILogger logger)
{
    logger.LogInformation($"{invocationContext.ConnectionId} has connected");
    // 将当前连接加入名为"OrderGroup"的群组
    await signalRGroupActions.AddAsync(new SignalRGroupAction
    {
        ConnectionId = invocationContext.ConnectionId,
        GroupName = "OrderGroup",
        Action = GroupAction.Add
    });
}

// 方式2：提供HTTP函数让客户端主动加入群组
[FunctionName("AddToGroup")]
public async Task AddToGroup(
    [HttpTrigger(AuthorizationLevel.Anonymous, "post")] GroupJoinRequest req,
    [SignalR(HubName = "MyHub")] IAsyncCollector<SignalRGroupAction> signalRGroupActions,
    ILogger log)
{
    await signalRGroupActions.AddAsync(new SignalRGroupAction
    {
        ConnectionId = req.ConnectionId,
        GroupName = req.GroupName,
        Action = GroupAction.Add
    });
}

public class GroupJoinRequest
{
    public string ConnectionId { get; set; }
    public string GroupName { get; set; }
}

步骤2：向群组发送消息 #

使用SignalR输出绑定，指定GroupName即可：

[FunctionName("SendToGroup")]
public async Task SendToGroup(
    [HttpTrigger(AuthorizationLevel.Anonymous, "post")] GroupMessage req,
    [SignalR(HubName = "MyHub")] IAsyncCollector<SignalRMessage> signalRMessages,
    ILogger log)
{
    await signalRMessages.AddAsync(new SignalRMessage
    {
        Target = "OrderEvent",
        GroupName = req.GroupName,
        Arguments = new[] { req.Order, req.Msg }
    });
}

public class GroupMessage
{
    public string GroupName { get; set; }
    public string Order { get; set; }
    public string Msg { get; set; }
}

内容的提问来源于stack exchange，提问作者John