BirthdayBot/Data/UserEntry.cs

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace BirthdayBot.Data;
[Table("user_birthdays")]
public class UserEntry {
    [Key]
    [Column("guild_id")]
    public long GuildId { get; set; }
    [Key]
    [Column("user_id")]
    public long UserId { get; set; }
    [Column("birth_month")]
    public int BirthMonth { get; set; }
    [Column("birth_day")]
    public int BirthDay { get; set; }
    [Column("time_zone")]
    public string? TimeZone { get; set; }
    [Column("last_seen")]
    public DateTimeOffset LastSeen { get; set; }

    [ForeignKey(nameof(GuildConfig.GuildId))]
    [InverseProperty(nameof(GuildConfig.UserEntries))]
    public GuildConfig Guild { get; set; } = null!;

    /// <summary>
    /// Gets if this instance is new and does not (yet) exist in the database.
    /// </summary>
    [NotMapped]
    public bool IsNew { get; set; }
}