Question

Let’s say I have a list of categories for navigation on a web app. Rather than selecting from the database for every user, should I add a function call in the application_onStart of the global.asax to fetch that data into an array or collection that is re-used over and over. If my data does not change at all – (Edit – very often), would this be the best way?

Answer 1

You can store the list items in the Application object. You are right about the application_onStart(), simply call a method that will read your database and load the data to the Application object.

In Global.asax

public class Global : System.Web.HttpApplication {     // The key to use in the rest of the web site to retrieve the list     public const string ListItemKey = 'MyListItemKey';     // a class to hold your actual values. This can be use with databinding     public class NameValuePair     {          public string Name{get;set;}          public string Value{get;set;}         public NameValuePair(string Name, string Value)         {             this.Name = Name;             this.Value = Value;         }     }      protected void Application_Start(object sender, EventArgs e)     {         InitializeApplicationVariables();     }       protected void InitializeApplicationVariables()     {         List<NameValuePair> listItems = new List<NameValuePair>();         // replace the following code with your data access code and fill in the collection         listItems.Add( new NameValuePair('Item1', '1'));         listItems.Add( new NameValuePair('Item2', '2'));         listItems.Add( new NameValuePair('Item3', '3'));         // load it in the application object         Application[ListItemKey] = listItems;     }  } 

Now you can access your list in the rest of the project. For example, in default.aspx to load the values in a DropDownList:

<asp:DropDownList runat='server' ID='ddList' DataTextField='Name' DataValueField='Value'></asp:DropDownList> 

And in the code-behind file:

protected override void OnPreInit(EventArgs e) {     ddList.DataSource = Application[Global.ListItemKey];     ddList.DataBind();     base.OnPreInit(e); }