C#•3mo ago

Beginner in EF Core and SQL Server in need for help

Hello, I am new here but I needed some help using my project. I need to connect to a SQL Server DB using .NET Core with EF Core. This is a simple example of my problem:

internal class UserModel
{
    [Key]
    [Column("ID")]
    [Required]
    public int Id { get; set; }
    [Column("Discord ID")]
    [Required]
    public long DiscordId { get; set; }
    [Column("Discord Name")]
    [Required]
    [MaxLength(32)]
    public required string DiscordName { get; set; }
}

internal class UserModel
{
    [Key]
    [Column("ID")]
    [Required]
    public int Id { get; set; }
    [Column("Discord ID")]
    [Required]
    public long DiscordId { get; set; }
    [Column("Discord Name")]
    [Required]
    [MaxLength(32)]
    public required string DiscordName { get; set; }
}

This would be the table mapped to a C# class, right? However, I need to work with User objects to perform methods and have fields that need to have private setters and getters etc. How would I do that? I was told to user another class like this to wrap around UserModel:

internal class User(UserModel model)
{
    public int Id { get; private set; } = model.Id;
    public long DiscordId { get; private set; } = model.DiscordId;
    public string DiscordName { get; private set; } = model.DiscordName;
        // Methods
}

internal class User(UserModel model)
{
    public int Id { get; private set; } = model.Id;
    public long DiscordId { get; private set; } = model.DiscordId;
    public string DiscordName { get; private set; } = model.DiscordName;
        // Methods
}

But I ended up in an unsolved problem. When using my code I will work with User objects, right? But I have some questions surrounding this idea (if the best - correct me please if there is any better way).

1) How do I create an instance of User if I don't have a UserModel object? 2) When adding a new UserModel to the DB, how do I do it if I am using User objects throughtout the project, not UserModel objects?

Probably dumb questions but basically, how I keep alternating between their uses? There is probably a better way to do it. If so, please I want to do this the best way possible. I am new to EF Core and SQL Server in general but willing to learn anything to make my project the best version possible.

3 Replies

Pagano•3mo ago

Another unrelated question that has been bugging my mind recently. I have four classes: User, Player, CoachingStaff and Team. Every Player and CoachingStaff are a User and their Primary Key is the User's Primary Key as a One-One relationship and the relationships between Team and the other classes which are defined by:

public class User {
  [Key]
  public int Id { get; set; }
}
public class Player {
  [Key]
  public required User User { get; set; }
}
public class CoachingStaff {
  [Key]
  public required User User { get; set; }
}
public class Team {
  [Key]
  public int Id { get; set; }
  public ICollection<Player> MainRoster { get; set; }
  public ICollection<Player> SubRoster { get; set; }
  public ICollection<CoachingStaff> Staff { get; set; }
}

public class User {
  [Key]
  public int Id { get; set; }
}
public class Player {
  [Key]
  public required User User { get; set; }
}
public class CoachingStaff {
  [Key]
  public required User User { get; set; }
}
public class Team {
  [Key]
  public int Id { get; set; }
  public ICollection<Player> MainRoster { get; set; }
  public ICollection<Player> SubRoster { get; set; }
  public ICollection<CoachingStaff> Staff { get; set; }
}

This is example is simplified for an easier understanding of the question

In this case, how do I limit a User to be either a Player, a CoachingStaff or nothing? I was told this One-Many relationship is wrong and Player and CoachingStaff should have a property like instead:

public class Player {
  [Key]
  public required User User { get; set; }
  public required Team Team { get; set; }
  [Required]
  public bool IsSub { get; set; }
}
public class CoachingStaff {
  [Key]
  public required User User { get; set; }
  public required Team Team { get; set; }
}

public class Player {
  [Key]
  public required User User { get; set; }
  public required Team Team { get; set; }
  [Required]
  public bool IsSub { get; set; }
}
public class CoachingStaff {
  [Key]
  public required User User { get; set; }
  public required Team Team { get; set; }
}

Pagano•3mo ago

This is the diagram for this part of the project

Pagano•3mo ago

As told earlier, I am a beginner when it comes to SQL Server and EF Core. I am more used to the Object Oriented Programming way of coding so my thought process tends to go on that way. Thanks for any help anyone can give me. Appreciate it! I have other questions too that I would love if someone could help me find out how some stuff work about EF Core. Let me know if so.

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Beginner in EF Core and SQL Server in need for help