.NET之AutoMapper使用
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介绍
是一个基于约定的对象-对象映射器。通俗地讲就是将一对象转换为另一个对象，前提是我们需要在这两个对象之间建立约定。支持框架：.Net 4.6.1+ 、.Net Standard 2.0+
官网：https://docs.automapper.org/
使用
本次示例环境：vs2019、.net5
生成代码
通过安装扩展或安装nuget包来更好地查看生成的代码，或者直接使用在线地址查看
详情：https://docs.automapper.org/en/latest/Understanding-your-mapping.html
var config = new MapperConfiguration(cfg => cfg.CreateMap<AddUserDto, User>());
var executionPlan = config.BuildExecutionPlan(typeof(AddUserDto), typeof(User));
//如果是操作数据库
var expression = context.Entities.ProjectTo<Dto>().Expression;
该代码不建议在发布后使用。
控制台操作
通过控制台对AutoMapper简单用法来一个了解，使用vs2019新建.Net5控制台应用
引用组件
<ItemGroup>
<PackageReference Include="AutoMapper" Version="10.1.1" />
<PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
</ItemGroup>
Newtonsoft.Json是为了显示转换为效果，序列化使用
默认约定映射
目标：将接收到的用户请求类转换为我们的用户实体类添加到数据库中
数据准备
用户实体类
public class User
{
public string Id { get; set; }
/// <summary>
/// 字符长度限制
/// </summary>
public string Name { get; set; }
/// <summary>
///图片地址
/// </summary>
public string Url { get; set; }
/// <summary>
/// 地址
/// </summary>
public string Address { get; set; }
/// <summary>
/// 生日
/// </summary>
public DateTime BirthDay { get; set; }
/// <summary>
/// 创建时间
/// </summary>
public DateTime CreateTime { get; set; }
}
添加用户请求类
public class AddUserDto
{
public string Id { get; set; }
/// <summary>
/// 字符长度限制
/// </summary>
public string Name { get; set; }
/// <summary>
///图片地址
/// </summary>
public string Url { get; set; }
/// <summary>
/// 省
/// </summary>
public string Province { get; set; }
/// <summary>
/// 市
/// </summary>
public string City { get; set; }
/// <summary>
/// 区
/// </summary>
public string Area { get; set; }
/// <summary>
/// 生日
/// </summary>
public DateTime BirthDay { get; set; }
/// <summary>
/// 创建时间
/// </summary>
public DateTime CreateTime { get; set; }
}
var addUser = new AddUserDto
{
Id = "123456",
Name = "azrng",
Province = "河南省",
City = "郑州市",
Area = "金水区",
BirthDay = DateTime.Parse("2021-05-20 13:14"),
CreateTime = DateTime.Now,
Url = "www.baidu.com/1.png"
};
//创建映射规则,第一个参数为源实体,第二个为目标实体
var config = new MapperConfiguration(cfg => cfg.CreateMap<AddUserDto, User>());
//var mapper = config.CreateMapper();
//or
var mapper = new Mapper(config);
//进行转换,得到目标实体
Console.WriteLine(JsonConvert.SerializeObject(mapper.Map<User>(addUser)));
//{"Id":"123456","Name":"azrng","Url":"www.baidu.com/1.png","Address":null,"BirthDay":"2021-05-20T13:14:00","CreateTime":"2021-05-20T16:09:08.6982869+08:00"}
自动配置
主动扫描从配置文件继承的类，并将它们加入配置
var assembly = Assembly.GetExecutingAssembly();
var config = new MapperConfiguration(cfg =>
{
cfg.AddMaps(assembly);
});
var mapper = new Mapper(config);
Console.WriteLine(JsonConvert.SerializeObject(mapper.Map<User>(addUser)));
WebAPI
安装组件
<PackageReference Include="AutoMapper" Version="10.1.1" />
<PackageReference Include="AutoMapper.Extensions.Microsoft.DependencyInjection" Version="8.1.1" />
ConfigureServices中将Automapper注入到依赖注入容器中
//只映射单个
//services.AddAutoMapper(typeof(UserProfile));
//映射程序集
//services.AddAutoMapper(typeof(Startup).Assembly);
//将继承于Profile的类批量映射
var profiles = Assembly.GetExecutingAssembly().DefinedTypes
.Where(t => typeof(Profile).GetTypeInfo().IsAssignableFrom(t.AsType()))
.Select(t => t.AsType()).ToArray();
services.AddAutoMapper(profiles);
创建包含用户实体类的WebAPI项目并且配置连接数据库。
public class User : IdentityBaseEntity
{
/// <summary>
/// 字符长度限制
/// </summary>
[Comment("名称")]
[Required]//必填
[StringLength(60, MinimumLength = 3)]//长度限制
public string Name { get; set; }
/// <summary>
/// 生日
/// </summary>
[Comment("生日")]
[Required]//必填
public DateTime BirthDay { get; set; }
/// <summary>
///头像
/// </summary>
[Comment("头像")]
[Required]//必填
[StringLength(200)]//长度限制
public string HeadImg { get; set; }
[Comment("创建时间")]
[DataType(DataType.Date)]//格式限制
public DateTime CreateTime { get; set; }
}
默认约定映射
使用添加用户场景操作
public class AddUserVm
{
/// <summary>
/// 名称
/// </summary>
public string Name { get; set; }
/// <summary>
/// 生日
/// </summary>
public DateTime BirthDay { get; set; }
/// <summary>
///头像
/// </summary>
public string HeadImg { get; set; }
}
用户映射配置
public class UserProfile : Profile
{
public UserProfile()
{
CreateMap<AddUserVm, User>();//默认映射
}
}
使用
private readonly OpenDbContext _dbContext;
private readonly IMapper _mapper;
public UserController(OpenDbContext dbContext, IMapper mapper)
{
_dbContext = dbContext;
_mapper = mapper;
}
[HttpPost]
public async Task<ActionResult<string>> AddAsync(AddUserVm dto)
{
//自行参数校验
var entity = _mapper.Map<User>(dto);
await _dbContext.AddAsync(entity).ConfigureAwait(false);
await _dbContext.SaveChangesAsync().ConfigureAwait(false);
return entity.Id;
}
添加成功
image.png
这里我们模拟存储的是头像的相对地址
自定义成员映射
这个时候我们需要查询某一个用户的信息，那么我们先来添加用户详情返回类
public class GetUserResult
{
/// <summary>
/// 名称
/// </summary>
public string Name { get; set; }
/// <summary>
///年
/// </summary>
public string Year { get; set; }
/// <summary>
/// 月
/// </summary>
public string Month { get; set; }
/// <summary>
/// 日
/// </summary>
public string Day { get; set; }
/// <summary>
///头像
/// </summary>
public string HeadImg { get; set; }
}
创建自定义成员映射
CreateMap<User, GetUserResult>()
//单独配置每一个成员
.ForMember(ur => ur.Year, u => u.MapFrom(src => src.BirthDay.Year))
.ForMember(ur => ur.Month, u => u.MapFrom(src => src.BirthDay.Month))
.ForMember(ur => ur.Day, u => u.MapFrom(src => src.BirthDay.Day))
.ForMember(ur => ur.HeadImg, u => u.MapFrom(src => "www.baidu.com/" + src.HeadImg));
查询操作
[HttpGet("{userId}")]
public async Task<ActionResult<GetUserResult>> GetDetails(string userId)
{
var result = await _dbContext.Users.Where(t => t.Id == userId).ProjectTo<GetUserResult>(_mapper.ConfigurationProvider).FirstOrDefaultAsync();
return Ok(result);
}
结果
{
"name": "azrng",
"year": "1990",
"month": "5",
"day": "29",
"headImg": "www.baidu.com/123456.png"
}
其他操作
命名公约
相互映射以下属性：property_name -> PropertyName
var config = new MapperConfiguration(cfg =>
{
//源成员的命名约定
cfg.SourceMemberNamingConvention = new LowerUnderscoreNamingConvention();
//目标成员的命名约定
cfg.DestinationMemberNamingConvention = new PascalCaseNamingConvention();
});
替换字符
替换属性名称字符 Source和Destination 的Avíator属性i不一样
var config = new MapperConfiguration(cfg =>
{
cfg.CreateMap<Source, Destination>();
//可能替换单个字符或者整个单词
cfg.ReplaceMemberName("í", "i");
//cfg.ReplaceMemberName("Airlina", "Airline");
});
var mapper = new Mapper(config);
Console.WriteLine(JsonConvert.SerializeObject(mapper.Map<Destination>(source)));
//{"Value":1,"Aviator":2,"SubAirlinaFlight":3}
识别前/后缀
因为有时候源/目标属性具有前后缀，因为名称不同，所以不能直接映射
var config = new MapperConfiguration(cfg =>
{
cfg.RecognizePrefixes("frm");//比如前缀都是frm区别
//cfg.CreateMap<a,b>
});
全局属性/字段过滤
映射时候选择一部分进行过滤
var config = new MapperConfiguration(cfg =>
{
cfg.ShouldMapField = fi => false;
cfg.ShouldMapProperty = pi => pi.GetMethod.IsPublic || pi.GetMethod.IsPrivate;
});
嵌套映射
当映射的类里面包含嵌套的类，那么需要将这个嵌套的类也给配置
var config = new MapperConfiguration(cfg =>
{
cfg.CreateMap<OuterSource, OuterDest>();
cfg.CreateMap<InnerSource, InnerDest>();//需要将嵌套的内容也配置
});
var outerSource = new OuterSource
{
Value = 2,
Inner = new InnerSource
{
OtherValue = 5
}
};
var mapper = new Mapper(config);
var outerDest = mapper.Map<OuterDest>(outerSource);
列表和数组
var config = new MapperConfiguration(cfg =>
{
cfg.CreateMap<Source, Destination>();
});
var listSourse = new List<Source>
{
new Source{ Value=1 },
new Source{ Value=2}
};
var mapper = new Mapper(config);
var listDest = mapper.Map<List<Destination>>(listSourse);
反向映射
var configuration = new MapperConfiguration(cfg =>
{
//约定映射
//cfg.CreateMap<Order, OrderDto>().ReverseMap();
//自定义反向映射
cfg.CreateMap<Order, OrderDto>()
.ForMember(od => od.CustomerName, o => o.MapFrom(src => src.Customer.Name))
.ReverseMap();
});
var mapper = new Mapper(configuration);
var order = new Order
{
Customer = new Customer
{
Name = "Bob"
},
Total = 15.8m
};
var orderDto = mapper.Map<OrderDto>(order);
忽略成员
使用IgnoreAttribute
忽略映射和/或验证中的单个目标成员：
using AutoMapper.Configuration.Annotations;
[AutoMap(typeof(Order))]
public class OrderDto {
[Ignore]
public decimal Total { get; set; }
类型映射配置
这相当于一个配置。CreateMap<Order, OrderDto>()
[AutoMap(typeof(Order))]
public class OrderDto {
// destination members
重定向到不同源成员
SourceMemberAttribute可以重定向到单独的命名成员
[AutoMap(typeof(User))]
public class GetUserResult
{
/// <summary>
/// 名称
/// </summary>
public string Name { get; set; }
/// <summary>
/// 名称2
/// </summary>
[SourceMember(nameof(User.Name))]
public string Name2 { get; set; }
/// <summary>
/// 名称3
/// </summary>
[SourceMember("Name")]
public string Name3 { get; set; }
}
注意：必须使用AutoMap，不能和CreateMap搭配使用
枚举映射
需要引用包
AutoMapper.Extensions.EnumMapping
配置操作
CreateMap<Source, Destination>()
.ConvertUsingEnumMapping(opt => opt
.MapValue(Source.First, Destination.Default))
.ReverseMap();//支持反过来映射
自定义类型转换器
特殊需求，将一种类型转换为另一种类型，例如字符串的源类型到 Int32 的目标类型可以直接使用Convert.ToInt32，复杂的需要自定义类型转换器
配置以及自定义转换器
var configuration = new MapperConfiguration(cfg => {
cfg.CreateMap<string, int>().ConvertUsing(s => Convert.ToInt32(s));
cfg.CreateMap<string, DateTime>().ConvertUsing(new DateTimeTypeConverter());
cfg.CreateMap<string, Type>().ConvertUsing<TypeTypeConverter>();
cfg.CreateMap<Source, Destination>();
});
public class DateTimeTypeConverter : ITypeConverter<string, DateTime>
{
public DateTime Convert(string source, DateTime destination, ResolutionContext context)
{
return System.Convert.ToDateTime(source);
}
}
public class TypeTypeConverter : ITypeConverter<string, Type>
{
public Type Convert(string source, Type destination, ResolutionContext context)
{
return Assembly.GetExecutingAssembly().GetType(source);
}
}
参考文档：https://docs.automapper.org/en/latest/Custom-type-converters.html
条件映射
仅当源对象中的属性baz大于或等于0时，才会映射该属性
var configuration = new MapperConfiguration(cfg => {
cfg.CreateMap<Foo,Bar>()
.ForMember(dest => dest.baz, opt => opt.Condition(src => (src.baz >= 0)));
});
通过PreCondition方法，解析值之前加条件，它在映射过程中运行更快。通过先调用先决条件，决定哪些是将要映射的源，然后调用条件，最后分配给目标值
var configuration = new MapperConfiguration(cfg => {
cfg.CreateMap<Foo,Bar>()
.ForMember(dest => dest.baz, opt => {
opt.PreCondition(src => (src.baz >= 0));
opt.MapFrom(src => {
// Expensive resolution process that can be avoided with a PreCondition
});
});
});
空替换
如果源值在成员中的任何位置为空，则空替换允许您为目标成员提供替代值。这意味着它不是从 null 映射，而是从您提供的值映射。
var config = new MapperConfiguration(cfg => cfg.CreateMap<Source, Dest>()
.ForMember(destination => destination.Value, opt => opt.NullSubstitute("Other Value")));
映射前或者映射后操作
一般不这么操作，因为经常不使用AutoMapper做该操作
var configuration = new MapperConfiguration(cfg => {
cfg.CreateMap<Source, Dest>()
.BeforeMap((src, dest) => src.Value = src.Value + 10)
.AfterMap((src, dest) => dest.Name = "John");
});
参考文档
转 https://www.modb.pro/db/77562https://docs.automapper.org/en/latest/Getting-started.html
标签：set,get,cfg,var,使用,AutoMapper,new,NET,public 来源： https://www.cnblogs.com/wl-blog/p/16403607.html