.NET\06_Microservices_Users\Users.APP\Domain\User.cs

                
                    using CORE.APP.Domain;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace Users.APP.Domain
{
    public class User : Entity
    {
        [Required, StringLength(30)]
        public string UserName { get; set; } // Reference Type: null can't be assigned since Required is used

        [Required, StringLength(15)]
        public string Password { get; set; } // Reference Type: null can't be assigned since Required is used

        [StringLength(50)]
        public string FirstName { get; set; } // Reference Type: null can be assigned, default value is null if no assignment

        [StringLength(50)]
        public string LastName { get; set; } // Reference Type: null can be assigned, default value is null if no assignment

        public Genders Gender { get; set; } // Value Type: null can't be assigned, default value is the first element's value if no assignment

        public DateTime? BirthDate { get; set; } // Value Type: null can be assigned since ? is used, default value is null if no assignment

        public DateTime RegistrationDate { get; set; } // Value Type: null can't be assigned, default value is
                                                       // 0001-01-01 00:00:00 (year-month-day hours-minutes-seconds) if no assignment

        // Way 1: decimal value type
        //public float Score { get; set; } // Value Type: null can't be assigned, default value is 0.0F if no assignment
        // Way 2: decimal value type
        //public double Score { get; set; } // Value Type: null can't be assigned, default value is 0.0 if no assignment
        // Way 3: decimal value type
        public decimal Score { get; set; } // Value Type: null can't be assigned, default value is 0.0M if no assignment

        public bool IsActive { get; set; } // Value Type: null can't be assigned, default value is false if no assignment

        public string Address { get; set; } // Reference Type: null can be assigned, default value is null if no assignment

        public int? CountryId { get; set; } // Value Type: null can be assigned since ? is used, default value is null if no assignment

        public int? CityId { get; set; } // Value Type: null can be assigned since ? is used, default value is null if no assignment



        // for group-users one to many relationship
        public int? GroupId { get; set; } // foreign key that references to the Groups table's Id primary key,
                                          // Value Type: null can be assigned since ? is used, default value is null if no assignment,
                                          // change int? to int if each user must have a group

        public Group Group { get; set; } // navigation property for retrieving related Group entity data of the User entity data in queries,
                                         // Reference Type: null can be assigned, default reference is null if no assignment



        // for users-roles many to many relationship
        public List<UserRole> UserRoles { get; set; } = new List<UserRole>(); // navigation property for retrieving related UserRole
                                                                              // entities data of the User entity data in queries,
                                                                              // initialized for preventing null reference exception

        [NotMapped] // no column in the Users table will be created for this property since NotMapped attribute is defined
        public List<int> RoleIds // helps to easily manage the UserRoles relational entities by Role Id values
        {
            // returns the Role Id values of the User entity
            get => UserRoles.Select(userRoleEntity => userRoleEntity.RoleId).ToList();

            // sets the UserRoles relational entities of the User entity by the assigned Role Id values
            set => UserRoles = value.Select(roleId => new UserRole() { RoleId = roleId }).ToList();
        }



        /// <summary>
        /// Gets or sets the refresh token assigned to the user.
        /// This token is used to obtain a new JWT without requiring re-authentication.
        /// </summary>
        public string RefreshToken { get; set; }

        /// <summary>
        /// Gets or sets the expiration date and time of the refresh token.
        /// This value determines when the refresh token becomes invalid. A null value implies no expiration is set.
        /// </summary>
        public DateTime? RefreshTokenExpiration { get; set; }
    }
}