How start sqldepndency with daynamic connection string in ASP.NET MVC 5

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I have some databases that work with single ASP.NET MVC project and all of the databases are the same and i used real time alarm with signalr but when i want to start sqldependencyin Application_Start method needed connection string, i set company name to cookie when user want to login and pass cookie to Application_Start to know which sqldependencyin which database started . but Application_Start run for first user,then for another user in another database i cant start sqldependency, and cookie is null in this method. please help

What I have tried:

protected void Application_Start(object sender, EventArgs e)
   {
       SqlConnectionString = ConfigurationManager.ConnectionStrings[HttpContext.Current.Request.Cookies["zone"].Value.ToString()].ConnectionString;

       if (!String.IsNullOrEmpty(SqlConnectionString))
           {
               if (SqlConnectionString.ToLower().StartsWith("metadata") && SqlConnectionString != null)
               {
                   System.Data.Entity.Core.EntityClient.EntityConnectionStringBuilder efbeulder = new System.Data.Entity.Core.EntityClient.EntityConnectionStringBuilder(SqlConnectionString);

                   SqlConnectionString = efbeulder.ProviderConnectionString;

                   SqlDependency.Start(SqlConnectionString);
               }

           }

   }

Posted 9-May-20 20:12pm

mohamad_ali

Updated 12-May-20 0:25am

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Richard Deeming · Accepted Answer · 2020-05-11T07:45:00

As the name suggests, the Application_Start event fires when the application starts. It doesn't run again until the application is restarted.

It will also potentially run before any user has logged in, which would mean you wouldn't have a cookie value.

According to the documentation[^], you can safely call SqlDependency.Start multiple times for the same connection, and only one listener will start for each connection string. So the simplest solution is to move your code to the Application_BeginRequest event instead:

C#

protected void Application_BeginRequest(object sender, EventArgs e)
{
    // Make sure we have a cookie value:
    var cookie = HttpContext.Current.Request.Cookies["zone"];
    if (cookie == null || string.IsNullOrEmpty(cookie.Value)) return;
    
    // Make sure the connection string exists:
    var connectionStringSetting = WebConfigurationManager.ConnectionStrings[cookie.Value];
    if (connectionStringSetting == null) return;
    
    // Make sure the connection string has a value:
    string sqlConnectionString = connectionStringSetting.ConnectionString;
    if (string.IsNullOrEmpty(sqlConnectionString)) return;
    
    // Turn an Entity Framework connection string into a SQL connection string:
    if (sqlConnectionString.StartsWith("metadata", StringComparison.OrdinalIgnoreCase))
    {
        var efBuilder = new System.Data.Entity.Core.EntityClient.EntityConnectionStringBuilder(sqlConnectionString);
        sqlConnectionString = efBuilder.ProviderConnectionString;
    }
    
    // Start the SQL dependency:
    SqlDependency.Start(sqlConnectionString);
}