Class Diagram for Social Media Platform

Question

In a professional social network, how would I represent connections between users? (like Linkedin) Should I create a connection class for which there would be an instance for every connection between 2 users or is that redundant? Should the user class instead have a self-association (reflexive association)?

Answer 1

Your User class would have a collection of Followings:

public class User
{
    // ... the other code is omitted for the brevity
    public IEnumerable<User> Followings { get; set; }
}

So if your database has the Following table:

CREATE TABLE Followings(
    User_Id INT NOT NULL, 
    Following_Id INT NOT NULL,
    DateCreated DATE NOT NULL,
);

Do not forget to create constraints and foreign keys in your table. Then it is possible to have Following class:

public class Followings {
    public UserId int { get; set; }
    public FollowingId int { get; set; }
    public DateCreated DateTime { get; set; }
}

and then you can write easily the following query:

select * from Following where UserId = x.id -- or vice versa