EF Code First ASP.NET C# Design

Question

I am trying to use EF Code first to create a database but I am not sure how to define the classes for the following relationship so that it is efficient.

We have a User and User has Friends, which in turn is a collection of User, so I was thinking of the following POCO Class

`//Class User
public class User
{
  public Guid UserId{get;set;}
  public string UserName{get;set;}
  public String UserAddress{get;set;}
  // other user properties
}

//Class Friend
public class Friend
{ 
  public Guid FriendId{get;set;} //unique identifier for Friend Table
  public virtual User CurrentUser{get;set;}
  public List<User> lstUserFriends {get;set;} //contains list of all friends that the     user has

}`

Does this look good performance-wise or do you think you can suggest an alternative?

It looks a bit strange to me... What is Friend? What not make "Friends" a property of User? (self referencing foreign key) — turtlepick
– turtlepick, Commented May 6, 2011 at 1:56

Andrew Cooper · Accepted Answer · 2011-05-06 01:59:35Z

4

Why not just do

public class User
{
  public Guid UserId{get;set;}
  public string UserName{get;set;}
  public String UserAddress{get;set;}
  public IList<User> Friends{get;set;}
  // other user properties
}

answered May 6, 2011 at 1:59

Andrew Cooper

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1 Comment

Sanchit Sharma Over a year ago

This seems to be only create one to one relation ship between each user as it has MembermemberId column created on each member row within the same table.

Ladislav Mrnka · Accepted Answer · 2011-05-06 08:00:03Z

3

You need self referencing many-to-many relation because use can have many friends but also can be friend of many users.

public class User
{
    public Guid UserId { get; set; }
    public string UserName { get; set; }
    public String UserAddress { get; set; }

    [InverseProperty("Friends")]
    public virtual ICollection<User> FriendWith { get; set; }
    [InverseProperty("FriendWith")]
    public virtual ICollection<User> Friends { get; set;} 
}

Or you can omit InverseProperty data annotation and use fluent mapping:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<User>()
                .HasMany(u => u.Friends)
                .WithMany(f => f.FriendWith);
    // I'm not sure but you can also need to add this:
    //          .WillCascadeOnDelete(false);
}

answered May 6, 2011 at 8:00

Ladislav Mrnka

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1 Comment

croisharp Over a year ago

Excellent answer, you just saved me a couple of hours.

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