在上篇中我們通過創建一個類並繼承autoMapper的Profile類

    public class Mappings : Profile
    {
        public Mappings()
        {
            CreateMap<UserDto, TbUser>();
        }
    }

這樣做有一種弊端，就是當傳輸對象很多的時候，還需要手動一個個的配置映射關係，維護起來相對來說也比較麻煩。

封裝AutoMapper

創建AutoMapperExtension擴展類

    /// <summary>
    /// AutoMapper擴展類
    /// </summary>
    public static class AutoMapperExtension
    {
        /// <summary>
        /// 將源對象映射到目標對象
        /// </summary>
        /// <typeparam name="T">實體類型</typeparam>
        /// <param name="obj">源對象</param>
        /// <returns>轉化之後的實體</returns>

        public static T MapTo<T>(this object obj)
        {
            if (obj == null) throw new Exception("異常");
            var config = new MapperConfiguration(ctx => ctx.CreateMap(obj.GetType(), typeof(T)));
            var mapper = config.CreateMapper();
            return mapper.Map<T>(obj);
        }

        /// <summary>
        /// 將源對象映射到目標對象
        /// </summary>
        /// <typeparam name="T">實體類型</typeparam>
        /// <param name="dto">源對象</param>
        /// <param name="entity">目標對象</param>
        /// <returns>轉化之後的實體</returns>
        public static T Map<T>(object dto, T entity)
        {
            var config = new MapperConfiguration(ctx => ctx.CreateMap(dto.GetType(), typeof(T)));
            var mapper = config.CreateMapper();
            var newModel = mapper.Map(dto, entity);
            return newModel;
        }
    }

修改業務層

去掉構造函數中IMapper註入

去掉啟動類Startup.cs中 services.AddAutoMapper(typeof(Mappings)) 方法

        /// <summary>
        /// 添加用戶
        /// </summary>
        /// <param name="dto">實體傳輸對象</param>
        /// <returns></returns>
        public int Add(UserDto dto)
        {
            //var info = _mapper.Map<UserDto, TbUser>(dto);
            var info = dto.MapTo<TbUser>();
            info.AddTime = DateTime.Now;
            info.UserId = Guid.NewGuid().ToString("N");
            //var user = new TbUser
            //{
            //    UserId = Guid.NewGuid().ToString("N"),
            //    Email = dto.Email,
            //    UserName = dto.UserName,
            //    AddTime = DateTime.Now
            //};
            _dbContext.Add(info);
            return _dbContext.SaveChanges();
        }
        /// <summary>
        /// 編輯用戶信息
        /// </summary>
        /// <param name="dto">實體傳輸對象</param>
        /// <returns></returns>
        public int Update(UserDto dto)
        {
            var user = _dbContext.TbUsers.Find(dto.UserId);
            if (user == null) throw new Exception("獲取用戶信息失敗");
            //user.UserName = dto.UserName;
            //user.Email = dto.Email;
            AutoMapperExtension.Map(dto, user);
            return _dbContext.SaveChanges();
        }

運行測試

跟封裝前一樣的效果