using LinqToDB.Mapping; using System; namespace SeniorAssistant.Models { public class Step : IHasTime { [PrimaryKey] [NotNull] public string Username { get; set; } [PrimaryKey] [NotNull] public DateTime Time { get; set; } [Association(ThisKey = nameof(Username), OtherKey = nameof(User.Username), CanBeNull = false)] public User user { get; set; } public long Value { get; set; } } }