Question

我目前正在开发一个用ASP.NET开发的网站。我使用SignalR发布数据库中的实时更改。例如，我有一个包含消息和NewMessageCount的表。每次NewMessageCount上升时，用户都会收到通知。但是我的问题是当用户点击通知时它没有减少。例如，如果用户有两个通知并单击Message选项卡，则会下降到0而不是1，然后是0。

以下是Hub

中的代码

     [HubMethodName("removeNotifications")]
    public string RemoveNotifications()
    {
        using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString))
        {
            using (SqlCommand command = new SqlCommand("UPDATE Messages SET NewMessageCount=@NewMessageCount", connection))
                {
                    command.Parameters.AddWithValue("@NewMessageCount", totalNewMessages);
                    command.Notification = null;
                    DataTable dt = new DataTable();
                    SqlDependency dependency = new SqlDependency(command);
                    dependency.OnChange += new OnChangeEventHandler(dependency_OnChange);

                    connection.Open();
                    var reader = command.ExecuteReader();
                }
                connection.Close();
            }
                IHubContext context = GlobalHost.ConnectionManager.GetHubContext<NotificationHub>();
                return context.Clients.All.RemoveNotification(totalNewMessages);
    }

对于客户端使用的script，以下是

<script type="text/javascript">
    $(function () {
        var notifications = $.connection.notificationHub;

        notifications.client.recieveNotification = function (totalNewMessages) {   
            $('#spanNewMessages').text(totalNewMessages);
        };
        $.connection.hub.start(function () {
            notifications.server.sendNotifications();
            $('.Message').click(function () {
                notifications.server.removeNotifications();
        })
        });
});         
</script>

我可能会犯一个明显的错误，但我似乎无法弄明白。在此先感谢您的所有帮助和支持。

Answer 1

试试这个：

    $(function () {
        var notifications = $.connection.notificationHub;
        var newMessages;
        notifications.client.recieveNotification = function (totalNewMessages) { 
            newMessages = parseInt(totalNewMessages);
            $('#spanNewMessages').text(totalNewMessages);
        };
        $.connection.hub.start(function () {
            notifications.server.sendNotifications();
            $('.Message').click(function () {
                newMessages--;
                notifications.server.removeNotifications(newMessages);
        })
        });
});

服务器：

 [HubMethodName("removeNotifications")]
    public string RemoveNotifications(int newMessages)
    {
        if(newMessages < 0)
        {
            return context.Clients.All.RecieveNotification(0);
        }
        using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString))
        {
            using (SqlCommand command = new SqlCommand("UPDATE Messages SET NewMessageCount=@NewMessageCount", connection))
                {
                    command.Parameters.AddWithValue("@NewMessageCount", newMessages);
                    command.Notification = null;
                    DataTable dt = new DataTable();
                    SqlDependency dependency = new SqlDependency(command);
                    dependency.OnChange += new OnChangeEventHandler(dependency_OnChange);

                    connection.Open();
                    var reader = command.ExecuteReader();
                }
                connection.Close();
            }
                IHubContext context = GlobalHost.ConnectionManager.GetHubContext<NotificationHub>();
                return context.Clients.All.RecieveNotification(newMessages);
    }

Answer 2

我设法通过简单地将查询实现到以下

来解决这个问题

string query = "UPDATE Messages SET NewMessageCount=NewMessageCount-1 WHERE UserName=@UserName AND NewMessageCount > 0";

减少更新查询

2 个答案: