Singleton Design Pattern in Asp.net using C#

codeproject Introduction When we want to make a only one instance of a class and also making sure that there is a global access point to that object then the design pattern we user is called Singleton. The pattern ensures that the class is instantiated only once and that all requests are di

Introduction

When we want to make a only one instance of a class and also making sure that there is a global access point to that object then the design pattern we user is called Singleton. The pattern ensures that the class is instantiated only once and that all requests are directed to that one and only object.

Usage

In asp.net you can use singleton through sessions or application variables easily however i will show you how to implement singleton object to User class.

Problem

In Asp.net to get user information like first name, surname or username through Memebership object does not look neat because to get UserID first you need to know user User.Identity.Name then use Membership.GetUser in order to get more detail for user.

Solution

I have created a interface called IUser which you can use anywhere on the page.

	public interface IUser
      {
          string Email { get; set; }
          string Firstname { get; set; }
          string Surname { get; set; }
          string UserID { get; set; }
          string Username { get; set; }
      }

Here is our Singleton class implementing IUser.

 public sealed class Singleton
       {
           private const string IUserSessionName = "User";
           private static readonly object padlock = new object();
           private static IUser objUser ;
           Singleton()
           {

           }
           /// <summary>
           /// Loading user information
           /// </summary>
           public static IUser IUserInstance
           {
               get
               {
                   lock (padlock)
                   {
                                              
                          if (null == Session[IUserSessionName])
                          {
                           
                           string userID = Membership.GetUser().ProviderUserKey.ToString();
                           // getting userinformation from database
                           objUser = new UserClass().GetUserInformation(userID);
                           Session[IUserSessionName] = objUser;
                          }
                          else
                          {
                          objUser = (IUser)Current.Session[IUserSessionName];
                          }
                      
           
                      return objUser;
                  }
               }
               set
               {
                   Session[IUserSessionName] = value;
               }
           }
          
           public static void UserInstanceFlush()
           {
               Session[IUserSessionName] = null;
           }

       }

Because of IuserSessionName you are also making sure that you will keep this session name unique and at only one place.

IUser is a static property which can be used on any page from Singleton.IUserInstance.UserID.

UserInstanceFlush flushes the session if you want to remove the session value.

Note: People may argue its not a pure Singleton object example because its one instance of object per user and i agree with all of them its a one instance of object per user when they get authenticated throughout for all pages in application and give you extra user properties through the interface IUser.

your feed is welcome.

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