一、什么是AutoMapper?
AutoMapper是一个简单的对象映射框架(OOM)，将一个对象映射到另一个对象。
二、AutoMapper的好处
以前的时候我们将DTO对象转换为Model对象时,我们必须将每一个属性都手动映射
实体类
/// <summary> /// 用户表 /// </summary> [Table("tb_User")] public class TbUser { /// <summary> /// 用户Id /// </summary> [Key] [Column("userId")] [StringLength(32)] public string UserId { get; set; } /// <summary> /// 用户名 /// </summary> [Column("userName")] [StringLength(20)] public string UserName { get; set; } /// <summary> /// 邮箱 /// </summary> [Column("email")] [StringLength(30)] public string Email { get; set; } /// <summary> /// 添加时间 /// </summary> [Column("addTime")] [Required] public DateTime AddTime { set; get; } }
DTO传输对象
/// <summary> /// 用户传输对象 /// </summary> public class UserDto { /// <summary> /// 用户Id /// </summary> [StringLength(32, ErrorMessage = "{0}最多{1}个字符"), Display(Name = "用户Id")] public string UserId { get; set; } /// <summary> /// 用户名 /// </summary> [StringLength(20, ErrorMessage = "{0}最多{1}个字符"), Display(Name = "用户名")] public string UserName { get; set; } /// <summary> /// 邮箱 /// </summary> [StringLength(30, ErrorMessage = "{0}最多{1}个字符"), Display(Name = "邮箱")] public string Email { get; set; } }
业务层
/// <summary> /// 业务处理 /// </summary> public class UserService : IUserService { private readonly MyDbContext _dbContext; /// <summary> /// 构造函数 /// </summary> /// <param name="dbContext"></param> public UserService(MyDbContext dbContext) { _dbContext = dbContext; } /// <summary> /// 添加用户 /// </summary> /// <param name="dto">实体传输对象</param> /// <returns></returns> public int Add(UserDto dto) { var user = new TbUser { UserId = Guid.NewGuid().ToString("N"), Email = dto.Email, UserName = dto.UserName, AddTime = DateTime.Now }; _dbContext.Add(user); return _dbContext.SaveChanges(); } /// <summary> /// 编辑用户信息 /// </summary> /// <param name="dto">实体传输对象</param> /// <returns></returns> public int Update(UserDto dto) { var user = _dbContext.TbUsers.Find(dto.UserId); if(user==null) throw new Exception("获取用户信息失败"); user.UserName = dto.UserName; user.Email = dto.Email; return _dbContext.SaveChanges(); } }
这样情况还可以，属性不是很多，如果属性过多（几十，几百），还需要手动赋值，简直太头疼了，还会导致大量的时间浪费在对象转换中，用AutoMapper，只需要简单的配置就可以完成两个对象之间的属性映射，开发中省去了属性转换的时间，从而提高工作效率。
三、使用AutoMapper
安装引用
通过程序包管理器控制台安装AutoMapper
Install-Package AutoMapper -version 9.0.0
Install-Package AutoMapper.Extensions.Microsoft.DependencyInjection -version 7.0.0
配置映射关系
创建一个类并继承autoMapper的Profile类
public class Mappings : Profile { public Mappings() { CreateMap<UserDto, TbUser>(); } }
注入服务
//注入AutoMapper服务，Mappings就是自己创建的映射类 services.AddAutoMapper(typeof(Mappings));
修改业务层代码
/// <summary> /// 业务处理 /// </summary> public class UserService : IUserService { private readonly MyDbContext _dbContext; /// <summary> /// 注入接口 /// </summary> private readonly IMapper _mapper; /// <summary> /// 构造函数 /// </summary> /// <param name="dbContext"></param> /// <param name="mapper"></param> public UserService(MyDbContext dbContext,IMapper mapper) { _dbContext = dbContext; _mapper = mapper; } /// <summary> /// 添加用户 /// </summary> /// <param name="dto">实体传输对象</param> /// <returns></returns> public int Add(UserDto dto) { var info = _mapper.Map<UserDto, TbUser>(dto); 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> /// 编辑用户信息 /// </summary> /// <param name="dto">实体传输对象</param> /// <returns></returns> public int Update(UserDto dto) { var user = _dbContext.TbUsers.Find(dto.UserId); if(user==null) throw new Exception("获取用户信息失败"); //user.UserName = dto.UserName; //user.Email = dto.Email; _mapper.Map(dto, user); return _dbContext.SaveChanges(); } }
运行测试
PS：一般在使用AutoMapper转换时dto中字段名称要跟实体对象定义一样才能转换成功。