AutoMapper 是一個(gè)對(duì)象-對(duì)象映射器，可以將一個(gè)對(duì)象映射到另一個(gè)對(duì)象。 官網(wǎng)地址：http:/// 1 入門例子public class Foo
{
public int ID { get; set; }
public string Name { get; set; }
}
public class FooDto
{
public int ID { get; set; }
public string Name { get; set; }
}
public void Map()
{
var config = new MapperConfiguration(cfg => cfg.CreateMap<Foo, FooDto>());
var mapper = config.CreateMapper();
Foo foo = new Foo { ID = 1, Name = "Tom" };
FooDto dto = mapper.Map<FooDto>(foo);
}2 注冊(cè)在使用 var config = new MapperConfiguration(cfg => cfg.CreateMap<Foo, FooDto>()); 每個(gè) AppDomain 只能進(jìn)行一次配置。這意味著放置配置代碼的最佳位置是在應(yīng)用程序啟動(dòng)中，例如 ASP.NET 應(yīng)用程序的 Global.asax 文件。 從 9.0 開(kāi)始 2.1 Profile
public class EmployeeProfile : Profile
{
public EmployeeProfile()
{
CreateMap<Employee, EmployeeDto>();
}
}
var config = new MapperConfiguration(cfg =>
{
cfg.AddProfile<EmployeeProfile>();
});
AutoMapper 也可以在指定的程序集中掃描從 var config = new MapperConfiguration(cfg =>
{
// 掃描當(dāng)前程序集
cfg.AddMaps(System.AppDomain.CurrentDomain.GetAssemblies());
// 也可以傳程序集名稱（dll 名稱）
cfg.AddMaps("LibCoreTest");
});3 配置3.1 命名約定默認(rèn)情況下，AutoMapper 基于相同的字段名映射，并且是 不區(qū)分大小寫 的。 但有時(shí)，我們需要處理一些特殊的情況。
我的理解，如果源類型和目標(biāo)類型分別采用了 蛇形命名法 和 駝峰命名法，那么就需要指定命名規(guī)則，使其能正確映射。 public class Foo
{
public int Id { get; set; }
public string MyName { get; set; }
}
public class FooDto
{
public int ID { get; set; }
public string My_Name { get; set; }
}
public void Map()
{
var config = new MapperConfiguration(cfg =>
{
cfg.CreateMap<Foo, FooDto>();
cfg.SourceMemberNamingConvention = new PascalCaseNamingConvention();
cfg.DestinationMemberNamingConvention = new LowerUnderscoreNamingConvention();
});
var mapper = config.CreateMapper();
Foo foo = new Foo { Id = 2, MyName = "Tom" };
FooDto dto = mapper.Map<FooDto>(foo);
}3.2 配置可見(jiàn)性默認(rèn)情況下，AutoMapper 僅映射 var config = new MapperConfiguration(cfg =>
{
cfg.ShouldMapProperty = p => p.GetMethod.IsPublic || p.SetMethod.IsPrivate;
cfg.CreateMap<Source, Destination>();
});需要注意的是，這里屬性必須添加 3.3 全局屬性/字段過(guò)濾默認(rèn)情況下，AutoMapper 嘗試映射每個(gè)公共屬性/字段。以下配置將忽略字段映射。 var config = new MapperConfiguration(cfg =>
{
cfg.ShouldMapField = fi => false;
});3.4 識(shí)別前綴和后綴var config = new MapperConfiguration(cfg =>
{
cfg.RecognizePrefixes("My");
cfg.RecognizePostfixes("My");
}3.5 替換字符var config = new MapperConfiguration(cfg =>
{
cfg.ReplaceMemberName("?", "A");
});這功能我們基本上用不上。 4 調(diào)用構(gòu)造函數(shù)有些類，屬性的 public class Commodity
{
public string Name { get; set; }
public int Price { get; set; }
}
public class CommodityDto
{
public string Name { get; }
public int Price { get; }
public CommodityDto(string name, int price)
{
Name = name;
Price = price * 2;
}
}AutoMapper 會(huì)自動(dòng)找到相應(yīng)的構(gòu)造函數(shù)調(diào)用。如果在構(gòu)造函數(shù)中對(duì)參數(shù)做一些改變的話，其改變會(huì)反應(yīng)在映射結(jié)果中。如上例，映射后 禁用構(gòu)造函數(shù)映射： var config = new MapperConfiguration(cfg => cfg.DisableConstructorMapping()); 禁用構(gòu)造函數(shù)映射的話，目標(biāo)類要有一個(gè)無(wú)參構(gòu)造函數(shù)。 5 數(shù)組和列表映射數(shù)組和列表的映射比較簡(jiǎn)單，僅需配置元素類型，定義簡(jiǎn)單類型如下： public class Source
{
public int Value { get; set; }
}
public class Destination
{
public int Value { get; set; }
}映射： var config = new MapperConfiguration(cfg =>
{
cfg.CreateMap<Source, Destination>();
});
IMapper mapper = config.CreateMapper();
var sources = new[]
{
new Source { Value = 5 },
new Source { Value = 6 },
new Source { Value = 7 }
};
IEnumerable<Destination> ienumerableDest = mapper.Map<Source[], IEnumerable<Destination>>(sources);
ICollection<Destination> icollectionDest = mapper.Map<Source[], ICollection<Destination>>(sources);
IList<Destination> ilistDest = mapper.Map<Source[], IList<Destination>>(sources);
List<Destination> listDest = mapper.Map<Source[], List<Destination>>(sources);
Destination[] arrayDest = mapper.Map<Source[], Destination[]>(sources);具體來(lái)說(shuō)，支持的源集合類型包括：
5.1 處理空集合映射集合屬性時(shí)，如果源值為 5.2 集合中的多態(tài)這個(gè)官方的文檔不是很好理解。我重新舉個(gè)例子。實(shí)體類如下： public class Employee
{
public int ID { get; set; }
public string Name { get; set; }
}
public class Employee2 : Employee
{
public string DeptName { get; set; }
}
public class EmployeeDto
{
public int ID { get; set; }
public string Name { get; set; }
}
public class EmployeeDto2 : EmployeeDto
{
public string DeptName { get; set; }
}數(shù)組映射代碼如下： var config = new MapperConfiguration(cfg =>
{
cfg.CreateMap<Employee, EmployeeDto>().Include<Employee2, EmployeeDto2>();
cfg.CreateMap<Employee2, EmployeeDto2>();
});
IMapper mapper = config.CreateMapper();
var employees = new[]
{
new Employee { ID = 1, Name = "Tom" },
new Employee2 { ID = 2, Name = "Jerry", DeptName = "R & D" }
};
var dto = mapper.Map<Employee[], EmployeeDto[]>(employees);可以看到，映射后， 如果去掉 6 方法到屬性映射AutoMapper 不僅能實(shí)現(xiàn)屬性到屬性映射，還可以實(shí)現(xiàn)方法到屬性的映射，并且不需要任何配置，方法名可以和屬性名一致，也可以帶有 例如下例的 public class Employee
{
public int ID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string GetFullName()
{
return $"{FirstName} {LastName}";
}
}
public class EmployeeDto
{
public int ID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string FullName { get; set; }
}7 自定義映射當(dāng)源類型與目標(biāo)類型名稱不一致時(shí)，或者需要對(duì)源數(shù)據(jù)做一些轉(zhuǎn)換時(shí)，可以用自定義映射。 public class Employee
{
public int ID { get; set; }
public string Name { get; set; }
public DateTime JoinTime { get; set; }
}
public class EmployeeDto
{
public int EmployeeID { get; set; }
public string EmployeeName { get; set; }
public int JoinYear { get; set; }
}如上例， var config = new MapperConfiguration(cfg =>
{
cfg.CreateMap<Employee, EmployeeDto>()
.ForMember("EmployeeID", opt => opt.MapFrom(src => src.ID))
.ForMember(dest => dest.EmployeeName, opt => opt.MapFrom(src => src.Name))
.ForMember(dest => dest.JoinYear, opt => opt.MapFrom(src => src.JoinTime.Year));
});8 扁平化映射對(duì)象-對(duì)象映射的常見(jiàn)用法之一是將復(fù)雜的對(duì)象模型并將其展平為更簡(jiǎn)單的模型。 public class Employee
{
public int ID { get; set; }
public string Name { get; set; }
public Department Department { get; set; }
}
public class Department
{
public int ID { get; set; }
public string Name { get; set; }
}
public class EmployeeDto
{
public int ID { get; set; }
public string Name { get; set; }
public int DepartmentID { get; set; }
public string DepartmentName { get; set; }
}如果目標(biāo)類型上的屬性，與源類型的屬性、方法都對(duì)應(yīng)不上，則 AutoMapper 會(huì)將目標(biāo)成員名按駝峰法拆解成單個(gè)單詞，再進(jìn)行匹配。例如上例中， 8.1 IncludeMembers如果屬性命名不符合上述的規(guī)則，而是像下面這樣： public class Employee
{
public int ID { get; set; }
public string Name { get; set; }
public Department Department { get; set; }
}
public class Department
{
public int DepartmentID { get; set; }
public string DepartmentName { get; set; }
}
public class EmployeeDto
{
public int ID { get; set; }
public string Name { get; set; }
public int DepartmentID { get; set; }
public string DepartmentName { get; set; }
}
var config = new MapperConfiguration(cfg =>
{
cfg.CreateMap<Employee, EmployeeDto>().IncludeMembers(e => e.Department);
cfg.CreateMap<Department, EmployeeDto>();
});9 嵌套映射有時(shí)，我們可能不需要展平。看如下例子： public class Employee
{
public int ID { get; set; }
public string Name { get; set; }
public int Age { get; set; }
public Department Department { get; set; }
}
public class Department
{
public int ID { get; set; }
public string Name { get; set; }
public string Heads { get; set; }
}
public class EmployeeDto
{
public int ID { get; set; }
public string Name { get; set; }
public DepartmentDto Department { get; set; }
}
public class DepartmentDto
{
public int ID { get; set; }
public string Name { get; set; }
}我們要將 var config = new MapperConfiguration(cfg =>
{
cfg.CreateMap<Employee, EmployeeDto>();
cfg.CreateMap<Department, DepartmentDto>();
});
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