Question

I have the next static class:

public static class GlobalVar
{
    public static string DatabaseName = "ProjectDatabase.mdf";

    public static AdminClass Admin;

    public static string TruePath = AppDomain.CurrentDomain.BaseDirectory;

    public static string TimeStampPattern = "dd/MM/yyyy HH:mm";

    static GlobalVar()
    {
        TruePath = TruePath.Remove(TruePath.Length - 1);
        Admin = new AdminClass("Admin", "Admin");
        GlobalStatus = new Dictionary<string, string>();
        string Query = "SELECT * FROM global_status";
        DataTable Types = MyAdoHelper.ExecuteDataTable(GlobalVar.DatabaseName, Query);
        foreach (DataRow Status in Types.Rows)
        {
            GlobalStatus.Add(Status["title"].ToString(), Status["info"].ToString());
        }
    }

    public static Dictionary<string, string> GlobalStatus; 

    public static string BasePath = HttpContext.Current.Request.ApplicationPath;
}

The GlobalStatus is a dictionary receives the custom errors the site may return. When I launch the project (Microsoft Visual Web developer 2008), it gives an error:

Object reference not set to an instance of an object.

when trying to get a value from GlobalStatus (eg. GlobalVar.GlobalStatus[“Page_NoAccess”]).

Only after a minute, when I launch the project again, it runs fine.

How can I fix this, like force it the browser to wait until it fills GlobalStatus. I need this class to initialize only once, since it contains global variables which I don’t want to be recalled every browser request.

Thanks

Answer 1

First of all, I want to suggest you global vars concept in an object-oriented code is a bad idea.

In order to solve your problem, you need to use built-in, out-of-the-box ASP.NET approaches: global application class.

Use Application_Start event handler and invoke initialization processes during this event .

Anything opposed to above statement is a bad idea.

Now… how to do it better

1. For everything that you find that are settings use AppSettings or settings files.
2. Using static constructors for application initialization is a bad idea. Create a static class with static methods like Initialize(), Start()…. Call them in Application_Start event of global application class.
3. Static classes with static fields and data in a multi-threaded environment like ASP.NET are a big fail. More than a thread can initialize your application at once. How your code manages this situation?.
4. Forget global variables concept in an object-oriented piece of software. Use settings (like I said in 1st point) or create constants or fields (static or instance ones) as part of the class that’s going to consume it.

UPDATE & NOTE
I suggest this MSDN article about static constructors in order to understand why these are a bad idea in ASP.NET initialization.