如何将聊天保存到数据库上下文 c#

Question

I'm trying to save chats on the database but I think I'm missing some part.

The context is inizialized:

public DbSet<ChatDB>? Chats { get; set; }

This is the class:

[Serializable]
public class ChatDB
{
    [Key]
    public string? ConnectionId { get; set; }
    public string? Username { get; set; }
    public List<MessagesDB> MessagesList { get; set; }

}

[Keyless]
[NotMapped]
public class MessagesDB
{
    public string? Body { get; set; }
    public bool Mine { get; set; }
    public string CSS => Mine ? "sent" : "received";
}

Here I'm adding messages to the database when the server receives them:

var FindUser = _context.Chats!.AsEnumerable();
foreach(var chat in FindUser)
{
     if(chat.Username == sender)
     {
        var messageslist = new MessagesDB(message, false);
        chat.MessagesList.Add(messageslist); //Here it gives me error - returned null.
        _context.Entry(chat).State = EntityState.Modified;
        await _context.SaveChangesAsync();
    }
}

when I go through all the chats by username:

var FindUser = _context.Chats.AsEnumerable();
foreach (var chat in FindUser)
{
      if (chat.Username == PassUserNameClicked)
      {
           foreach(var messages in chat.MessagesList)
           {
                <div class="@messages.CSS">
                <div class="user">@chat.Username</div>
                <div class="msg">@messages.Body</div>
                </div>
            }
       }
 }

when I build the migration it gives me all empty:

public partial class AddChatsToDb : Migration
{
    protected override void Up(MigrationBuilder migrationBuilder)
    {

    }

    protected override void Down(MigrationBuilder migrationBuilder)
    {

    }
}

Do you guys no what is going on? I believe the "list" inside the class broke the migration.

Answer 1

If anyone needs I figured it out, this is the class:

[Serializable]
public class ChatDB
{
    [Key]
    public string? ConnectionId { get; set; }
    public string? Username { get; set; }
    public MessagesDB? MessagesDBs { get; set; }
}

[Serializable]
public class MessagesDB
{
    [Key]
    public string? Id { get; set; }
    public string? WhoIs { get; set; }
    public string? Body { get; set; }
    public bool Mine { get; set; }
    public DateTime Time { get; set; }
    public string? ConnectionId { get; set; }
    public string CSS => Mine ? "sent" : "received";
}

Just compile it, c# will connect the two classes via "ConnectionId".