SignalR 和 MVC 的 SQLDependency。 OnChange 只触发一次答案

【问题标题】：SQLDependency with SignalR and MVC. OnChange only firing onceSignalR 和 MVC 的 SQLDependency。 OnChange 只触发一次
【发布时间】：2014-01-19 20:10:12
【问题描述】：

我能够在我的网站仪表板上显示实时行更新。但是，当尝试对通知做几乎完全相同的事情时，我的 onchange 事件只会触发一次。仪表板更新正在使用 SignalR 连接，并且它在 100% 的时间内工作。所有代码实际上都是相同的，除了我每次都在仪表板上获取每一行，并且在获取它们之后没有对数据库进行任何更新。

这就是我想要做的。

在 dbo.SystemNotifications 中插入一行，标志为 Sent = 0
订阅更改并使用 jQuery.noty 显示新插入
将记录更新为已发送 = 1

这在我第一次或任何时候刷新浏览器时都有效，但 SQLDependency onchange 要么在此之后再次触发，要么根本不再触发。

在我的 CUSTOM.JS 文件中

$(document).ready(function ( $ ) {
    var notificationHub = $.connection.notyHub;

    notificationHub.client.showNotification = function () {
        getNotifications();
        markSet();
    };

    $.connection.hub.start();
    getNotifications();

});

function getNotifications() {
    $.ajax({
        url: '../Notification/GetNotifications',
        type: 'GET',
        global: false,
        datatype: 'json',
        success: function (data) {
            if (data.length > 0) {
                for (var i = 0; i < data.length; i++) {
                    noty({
                        text: data[i].NotificationText,
                        type: 'information',
                        timeout: 0,
                        closeWith: ['hover'],
                        maxVisible: 1
                    });

                    markSent(data[i].ID);
                }
            }
        }
    });
}

function markSent(id) {
    $.ajax({                  
        url: '../Notification/MarkNotificationSent',
        type: 'POST',
        data: JSON.stringify({ notyID: id }),
        dataType: 'json',
        contentType: 'application/json',
        global: false,        
        error: function (req, status, error) {
            alert("R: " + req + " S: " + status + " E: " + error);
        }
    });
}

我的控制器

 public class NotificationController : CaseEnhancedController
    {
        private readonly NotificationRepository notyRepo = new NotificationRepository();
        private ReaderWriterLockSlim methodLock = new ReaderWriterLockSlim();

        [OutputCache(Duration = 0)]
        public JsonResult GetNotifications()
        {
            try
            {
                methodLock.EnterWriteLock();

                IEnumerable<Notification> notifications = notyRepo.GetData();
                JsonResult notysJSon = new JsonResult();
                notysJSon.JsonRequestBehavior = JsonRequestBehavior.AllowGet;
                notysJSon.Data = notifications;
                return notysJSon;
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (methodLock.IsWriteLockHeld)
                    methodLock.ExitWriteLock();
            }
        }

        [HttpPost]
        public JsonResult MarkNotificationSent(string notyID)
        {
            string sConn = "Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=SirenCMNew;Data Source=localhost";

            try
            {
                methodLock.EnterWriteLock();

                using (SqlConnection connection = new SqlConnection(sConn))
                {
                    if (connection.State == ConnectionState.Closed)
                        connection.Open();

                    using (SqlCommand cmd = new SqlCommand("[dbo].[spMarkNotificationSent]", connection))
                    {
                        cmd.CommandType = CommandType.StoredProcedure;

                        SqlParameter idParm = new SqlParameter
                        {
                            Value = notyID,
                            SqlDbType = SqlDbType.BigInt,
                            ParameterName = "ID"
                        };

                        cmd.Parameters.Add(idParm);
                        cmd.ExecuteNonQuery();
                    }
                }

                return Json(new { result = notyID }, JsonRequestBehavior.AllowGet);
            }
            catch (Exception ex)
            {
                return Json(new { result = 0 }, JsonRequestBehavior.AllowGet);
            }
            finally
            {
                if (methodLock.IsWriteLockHeld)
                    methodLock.ExitWriteLock();
            }
        }

我的仓库

public class NotificationRepository
{
    string sConn = "Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=SirenCMNew;Data Source=localhost";

    public IEnumerable<Notification> GetData()
    {
        try
        {
            using (var connection = new SqlConnection(sConn))
            {
                connection.Open();
                using (SqlCommand command = new SqlCommand(@"EXEC [dbo].[spGetUnsentNotifications]", connection))
                {
                    command.Notification = null;

                    SqlDependency dependency = new SqlDependency(command);
                    dependency.OnChange += new OnChangeEventHandler(OnChange);

                    if (connection.State == ConnectionState.Closed)
                        connection.Open();

                    using (var reader = command.ExecuteReader())
                        return reader.Cast<IDataRecord>()
                            .Select(x => new Notification()
                            {    
                                ID = x.GetInt64(0),
                                NotificationText = x.GetString(1)                                   
                            }).ToList();
                }
            }
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

    private void OnChange(object sender, SqlNotificationEventArgs e)
    {
        SqlDependency dependency = sender as SqlDependency;
        dependency.OnChange -= OnChange;

        if (e.Info == SqlNotificationInfo.Insert)
        {
            NotificationHub.Show();
        }
    }

我的集线器

 [HubName("notyHub")]
    public class NotificationHub : Hub
    {
        public static void Show()
        {
            IHubContext context = GlobalHost.ConnectionManager.GetHubContext<JobInfoHub>();            
            context.Clients.All.showNotification();
        }     
    }

存储过程

CREATE PROCEDURE [dbo].[spGetUnsentNotifications]
    AS

    SELECT
        ID, NotificationText
    FROM
        dbo.SystemNotifications
    WHERE
        Sent = 0

GO

CREATE PROCEDURE dbo.spMarkNotificationSent

@ID bigint

AS

UPDATE 
    dbo.SystemNotifications
SET
    Sent = 1
WHERE
    ID = @ID

【问题讨论】：

标签： jquery asp.net-mvc signalr sqldependency

【解决方案1】：

我终于想通了。我不得不采取不同的方法。这是我的做法

存储库

if (e.Info == SqlNotificationInfo.Insert)
        {
            id = GetLastRecord();
        }

        if (id != 0)
            DeleteNotification(id);

        GetData();
    }

    private long GetLastRecord()
    {
        Notification notification = null;
        long id = 0;
        try
        {
            using (var connection = new SqlConnection(sConn))
            {
                connection.Open();
                using (SqlCommand command = new SqlCommand(@"SELECT TOP 1 ID, NotificationText FROM dbo.SystemNotifications with(nolock)", connection))
                {
                    if (connection.State == ConnectionState.Closed)
                        connection.Open();

                    using (var reader = command.ExecuteReader())
                    {
                        while (reader.Read())
                        {
                            notification = new Notification
                            {
                                ID = (long)reader.GetSqlInt64(0)
                                , NotificationText = reader.GetString(1)
                            };
                        }
                    }

                    if (null != notification)
                    {
                        NotificationHub.Show(notification);
                        id = notification.ID;
                    }
                    return id;
                }
            }
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

    private static void DeleteNotification(long notyID)
    {
        string sConn = "Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=SirenCMNew;Data Source=localhost";

        try
        {

            using (SqlConnection connection = new SqlConnection(sConn))
            {
                if (connection.State == ConnectionState.Closed)
                    connection.Open();

                using (SqlCommand cmd = new SqlCommand("[dbo].[spDeleteNotification]", connection))
                {
                    cmd.CommandType = CommandType.StoredProcedure;

                    SqlParameter idParm = new SqlParameter
                    {
                        Value = notyID,
                        SqlDbType = SqlDbType.BigInt,
                        ParameterName = "ID"
                    };

                    cmd.Parameters.Add(idParm);
                    cmd.ExecuteNonQuery();
                }
            }

        }
        catch (Exception ex)
        {
            //TODO
        }
    }

集线器

[HubName("notyHub")]
public class NotificationHub : Hub
{
    public static void Show(Notification notification)
    {
        IHubContext context = GlobalHost.ConnectionManager.GetHubContext<NotificationHub>();
        context.Clients.All.showNoty(notification.ID, notification.NotificationText);

    }     
}

控制器

 public class NotificationController : CaseEnhancedController
{
    private readonly NotificationRepository notyRepo = new NotificationRepository();
    private ReaderWriterLockSlim methodLock = new ReaderWriterLockSlim();

    [OutputCache(Duration = 0)]
    public JsonResult GetNotifications()
    {
        int count = 0;

        try
        {
            methodLock.EnterWriteLock();

            IEnumerable<Notification> notifications = notyRepo.GetData();
            count = notifications.Count();
            JsonResult notysJSon = new JsonResult();
            notysJSon.JsonRequestBehavior = JsonRequestBehavior.AllowGet;
            notysJSon.Data = notifications;
            return notysJSon;
        }
        catch (Exception ex)
        {
            throw ex;
        }
        finally
        {
            if (methodLock.IsWriteLockHeld)
                methodLock.ExitWriteLock();

            if (count > 0)
                DeleteNotifications();
        }
    }

    private static void DeleteNotifications()
    {
        string sConn = "Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=SirenCMNew;Data Source=localhost";

        try
        {
            using (SqlConnection connection = new SqlConnection(sConn))
            {
                if (connection.State == ConnectionState.Closed)
                    connection.Open();

                using (SqlCommand cmd = new SqlCommand("[dbo].[spDeleteAllNotifications]", connection))
                {
                    cmd.CommandType = CommandType.StoredProcedure;
                    cmd.ExecuteNonQuery();
                }
            }
        }
        catch (Exception ex)
        {
            //TODO
        }
    }

JQUERY

$(function () {
 var notificationHub = $.connection.notyHub;

notificationHub.client.showNoty = function (id, message) {
    showNotification(id, message);
};

$.connection.hub.start();
getNotifications();
}

function showNotification(id, message)
{
    noty({
        text: message,
        type: 'information',
        timeout: 0,
        closeWith: ['hover'],
        maxVisible: 1
    });
}

function getNotifications() {
$.ajax({
    url: '../Notification/GetNotifications',
    type: 'GET',
    global: false,
    datatype: 'json',
    success: function (data) {
        if (data.length > 0) {
            for (var i = 0; i < data.length; i++) {
                showNotification(data[i].ID, data[i].NotificationText);
            }
        }
    }
});
}

【讨论】：

你找到第二次没有触发的原因了吗？我有同样的问题。

【解决方案2】：

您应该将您的 sp 写入以下方法：

CREATE PROCEDURE [dbo].[spGetUnsentNotifications]
AS

SELECT
    [ID], [NotificationText]
FROM
    [dbo].[SystemNotifications]
WHERE
    [Sent] = 0

GO

CREATE PROCEDURE [dbo].[spMarkNotificationSent]

@ID bigint

AS

UPDATE 
[dbo].[SystemNotifications]
SET [Sent] = 1 
WHERE [ID] = @ID

【讨论】：