C# Lazy loading & Ajax

Question

I have a class where some properties are going back to the database, ONLY when they are called. So, let consider the following example:

class User
{
   public int UserID { get; internal set; }
   public string UserName { get; set; }
   public Role[] Roles
   {
      get
      {
         if (this.UserID > 0)
            return RoleRepository.GetByUserID(this.UserID).ToEntityArray();
         else
            return RoleRepository.GetByUserName(this.UserName).ToEntityArray();
      }
   }
}

There is also a Role class, but that's probably not important. The 'Roles' property in the 'User' class is kind of like lazy loading. It is only retrieving the info when that property is accessed. The question is how can I use JQuery to ensure that the lazy loading occurs or is that even possible? Any articles on this concept would also be helpful.

Thanks

Which technology are you using to interact with your C# from jQuery? — Cᴏʀʏ
– Cᴏʀʏ, Commented Nov 12, 2010 at 14:13
Do you mean like windows forms or ASP.NET? Or do u mean the back-end? For the front end, its ASP.net mvc and backend its sql server '05. — Skadoosh
– Skadoosh, Commented Nov 12, 2010 at 15:10

hunter · Accepted Answer · 2010-11-12 14:24:42Z

I don't see what jQuery has to do with this at all.

Touching that Property will trigger the lazy-load.

If you use JQuery to call some HttpHandler/WebMethod/ActionMethod/etc, as soon as you try to iterate through or access that Property it is going to load that data

Also, rather than having that biz logic in your domain object you could try a delegate approach to keep "how" data is bound to that Property in its proper place

class User
{
   public int UserID { get; internal set; }
   public string UserName { get; set; }

   public delegate Role[] GetRolesDelegate(int userId, string username);

   public GetRolesDelegate GetRoles { get; set; }

   Role[] _roles;
   public Role[] Roles
   {
      get
      {
          if (_roles == null)
          {
              _roles = GetRoles == null 
                  ? new Role { } 
                  : GetRoles(UserID, UserName).ToEntityArray();
          }
          return _roles;
      }
   }
}

Then you could bind that like so:

User user = new User();

user.GetRoles = RoleRepository.GetRoles;

hunter · Accepted Answer · 2010-11-12 15:12:35Z

0

Like hunter I'm not sure what jQuery has to do with this. To make the Roles property lazy load add a private backing property that stores the value the first time it is accessed from the repository. Then, for subsequent accesses, you can just return that private backing variable, rather than going through the RoleRepository. Something like:

class User
{
   public int UserID { get; internal set; }
   public string UserName { get; set; }
   private Role[] _roles;

   public Role[] Roles
   {
      get
      {
         if (_roles == null)
         {    
             if (this.UserID > 0)
                _roles = RoleRepository.GetByUserID(this.UserID).ToEntityArray();
             else
                _roles = RoleRepository.GetByUserName(this.UserName).ToEntityArray();
         }

         return _roles;
      }
   }
}

edited Nov 12, 2010 at 15:12

hunter

63.7k19 gold badges115 silver badges115 bronze badges

answered Nov 12, 2010 at 14:20

Dan Diplo

25.4k4 gold badges71 silver badges90 bronze badges

2 Comments

Aurelien Ribon Over a year ago

You mean if (_roles == null) ? If not, it's not lazy-loading, it's never-loading :)

Richard Friend Over a year ago

could call that bone-idle-loading ;-)

Collectives™ on Stack Overflow

C# Lazy loading & Ajax

2 Answers 2

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related