Question

I am working on a social networking site and it has a wall like facebook where user can post status, pics and stuff. Building a wall just for a user is not hard thing. I have structure like this.

Wall
  {
     Id,
     ToUserId (BigInt) (Owner of wall)
     ByUserId (The person who is posting)
     Content  (message, pic or something else)
     more fields....
  }

This wall is just for a user, I cant reuse it, For example, I am thinking site will have
other objects too like Pages, Groups etc. so all the objects will have Wall for them. I dont want to create separate table for each wall.

Then I thought, I can have ObjectId instead of ToUserId and my structure will be like this.

  Wall
  {
     Id,
     ObjectId (BigInt)(PageId/UserId/GroupId (one of them))
     ByUserId (The person who is posting)
     Content  (message, pic or something else)
     more fields....
  }

As I am using Increment field in my tables, A page can have same Id which a user has. so that is again a problem.

Next, I thought, my object should be string type

Wall
  {
     Id,
     ObjectId (string(10))(PageId/UserId/GroupId (one of them))
     ByUserId (The person who is posting)
     Content  (message, pic or something else)
     more fields....
  }

Now for a User, I will append “U” to the number so Object Id’s will be “1U”,”2U” and for pages they will be “1P”,”2P” and for a group “1G”, “2G”.

But I am still not convince, Would like to hear to expert advice on this.

Update

Thanks guys, The problem, I am having is, how can I keep one table for all types of walls.

A wall for a User
A Wall for a Page
A Wall for a Group

If you look at facebook, its one wall or atleast, I want to build it, so it should be attached to any object (to a user, to a page or to a group or to anything).

I hope this makes more sense now.

Answer 1

I don’t understand why you’re trying to create some kind of “string” reference structure. That doesn’t seem “relational”.

How about this.

A User has many Posts.

A User has one Wall.

A Post has one Wall.

A Post has one User.

A Wall has many Posts.

A Wall has one User.

POCO’s (because i can’t be bothered writing SQL)

public class User
{
   public int UserId { get; set; }
   public ICollection<Post> Posts { get; set; } // the Posts this user has written. Could be against different Wall's
   public Wall Wall { get; set; } // the User's wall.
}

public class Post
{
   public int PostId { get; set; }
   public User User { get; set; } // the User who wrote the post. 
   public Wall Wall { get; set; } // the Wall this Post belongs to. 
}

public class Wall
{
   public int WallId { get; set; }
   public ICollection<Post> Posts { get; set; } // all the posts on this Wall.
}

Assumptions:

• A Post can only be done against one Wall.