C# 使用AutoMapper展平嵌套对象的更好方法?
我一直在将域对象展平为DTO,如下例所示:C# 使用AutoMapper展平嵌套对象的更好方法?,c#,nested,automapper,flatten,C#,Nested,Automapper,Flatten,我一直在将域对象展平为DTO,如下例所示: public class Root { public string AParentProperty { get; set; } public Nested TheNestedClass { get; set; } } public class Nested { public string ANestedProperty { get; set; } } public class Flattened { public s
public class Root
{
public string AParentProperty { get; set; }
public Nested TheNestedClass { get; set; }
}
public class Nested
{
public string ANestedProperty { get; set; }
}
public class Flattened
{
public string AParentProperty { get; set; }
public string ANestedProperty { get; set; }
}
// I put the equivalent of the following in a profile, configured at application start
// as suggested by others:
Mapper.CreateMap<Root, Flattened>()
.ForMember
(
dest => dest.ANestedProperty
, opt => opt.MapFrom(src => src.TheNestedClass.ANestedProperty)
);
// This is in my controller:
Flattened myFlattened = Mapper.Map<Root, Flattened>(myRoot);
公共类根目录
{
公共字符串AParentProperty{get;set;}
公共嵌套的TheNestedClass{get;set;}
}
公共类嵌套
{
公共字符串属性{get;set;}
}
公务舱被夷为平地
{
公共字符串AParentProperty{get;set;}
公共字符串属性{get;set;}
}
//在应用程序启动时配置的配置文件中,我添加了与以下内容等效的内容
//正如其他人所建议的那样:
Mapper.CreateMap()
福门博先生
(
dest=>dest.ANestedProperty
,opt=>opt.MapFrom(src=>src.TheNestedClass.ANestedProperty)
);
//这在我的控制器中:
展平MyFlatted=Mapper.Map(myRoot);
我已经看了很多例子,到目前为止,这似乎是一种扁平化嵌套层次结构的方法。但是,如果子对象具有多个属性,则这种方法不会节省太多编码
我发现这个例子:
但它需要Map()函数所需的映射对象的实例,据我所知,该函数不适用于概要文件
我是汽车制造商的新手,所以我想知道是否有更好的方法来做到这一点 在最新版本的AutoMapper中,有一个命名约定,可以用来避免多个.formMember语句 在您的示例中,如果将展开类更新为:
public class Flattened
{
public string AParentProperty { get; set; }
public string TheNestedClassANestedProperty { get; set; }
}
您可以避免使用FormMember语句:
Mapper.CreateMap<Root, Flattened>();
Mapper.CreateMap();
自动映射将(按照约定)将
根.TheNestedClass.ANestedProperty
映射到展平的.TheNestedClassANestedProperty
。老实说,当你使用真实的类名时,它看起来不那么难看 2种可能的解决方案:
Mapper.CreateMap<Nested, Flattened>()
.ForMember(s=>s.AParentProperty, o=>o.Ignore());
Mapper.CreateMap<Root, Flattened>()
.ForMember(d => d.ANestedProperty, o => o.MapFrom(s => s.TheNestedClass));
我编写了扩展方法来解决类似的问题:
public static IMappingExpression<TSource, TDestination> FlattenNested<TSource, TNestedSource, TDestination>(
this IMappingExpression<TSource, TDestination> expression,
Expression<Func<TSource, TNestedSource>> nestedSelector,
IMappingExpression<TNestedSource, TDestination> nestedMappingExpression)
{
var dstProperties = typeof(TDestination).GetProperties().Select(p => p.Name);
var flattenedMappings = nestedMappingExpression.TypeMap.GetPropertyMaps()
.Where(pm => pm.IsMapped() && !pm.IsIgnored())
.ToDictionary(pm => pm.DestinationProperty.Name,
pm => Expression.Lambda(
Expression.MakeMemberAccess(nestedSelector.Body, pm.SourceMember),
nestedSelector.Parameters[0]));
foreach (var property in dstProperties)
{
if (!flattenedMappings.ContainsKey(property))
continue;
expression.ForMember(property, opt => opt.MapFrom((dynamic)flattenedMappings[property]));
}
return expression;
}
publicstaticimappingexpression(
这个IMappingExpression表达式,
表达式嵌套选择器,
IMappingExpression嵌套的映射表达式)
{
var dstProperties=typeof(tdestinition).GetProperties().Select(p=>p.Name);
var flattedMappings=nestedMappingExpression.TypeMap.GetPropertyMaps()
.Where(pm=>pm.IsMapped()&&!pm.IsIgnored())
.ToDictionary(pm=>pm.DestinationProperty.Name,
pm=>Expression.Lambda(
表达式.MakeMemberAccess(nestedSelector.Body,pm.SourceMember),
nestedSelector.Parameters[0]);
foreach(dstProperties中的var属性)
{
如果(!FlattedMappings.ContainsKey(属性))
继续;
expression.ForMember(属性,opt=>opt.MapFrom((动态)flattedMappings[property]);
}
返回表达式;
}
因此,在您的情况下,它可以这样使用:
var nestedMap = Mapper.CreateMap<Nested, Flattened>()
.IgnoreAllNonExisting();
Mapper.CreateMap<Root, Flattened>()
.FlattenNested(s => s.TheNestedClass, nestedMap);
var nestedMap=Mapper.CreateMap()
.ignoreall不存在();
Mapper.CreateMap()
.flatternested(s=>s.TheNestedClass,nestedMap);
ignoreallnoexisting()
来自
虽然它不是通用的解决方案,但对于简单的情况应该足够了
所以
要改进另一个答案,请为这两个映射指定
MemberList.Source
,并将嵌套属性设置为忽略。然后验证通过OK
Mapper.Initialize(cfg =>
{
cfg.CreateMap<SrcNested, DestFlat>(MemberList.Source);
cfg.CreateMap<SrcRoot, DestFlat>(MemberList.Source)
.ForSourceMember(s => s.Nested, x => x.Ignore())
.AfterMap((s, d) => Mapper.Map(s.Nested, d));
});
Mapper.AssertConfigurationIsValid();
var dest = Mapper.Map<SrcRoot, DestFlat>(src);
Mapper.Initialize(cfg=>
{
CreateMap(MemberList.Source);
CreateMap(MemberList.Source)
.ForSourceMember(s=>s.Nested,x=>x.Ignore())
.AfterMap((s,d)=>Mapper.Map(s.Nested,d));
});
assertConfigurationsValid();
var dest=Mapper.Map(src);
不确定这是否为以前的解决方案增加了价值,但您可以通过两步映射来实现。如果父级和子级之间存在命名冲突(最后一次获胜),请小心按正确顺序映射
Mapper.CreateMap();
CreateMap();
var展平=新展平();
Mapper.Map(根,展平);
Map(root.TheNestedClass,展平);
我更喜欢避免使用旧的静态方法,而是这样做
将映射定义放入配置文件中。我们首先映射根,然后应用嵌套对象的映射。注意上下文的用法
公共类映射配置文件:配置文件
{
公共映射配置文件()
{
CreateMap()
.AfterMap((src,dest,context)=>context.Mapper.Map(src.TheNestedClass,dest));
CreateMap();
}
}
定义从根到展平和嵌套到展平的映射的优点是,您可以保留对属性映射的完全控制,例如,如果目标属性名称不同,或者希望应用转换等
XUnit测试:
[Fact]
public void Mapping_root_to_flattened_should_include_nested_properties()
{
// ARRANGE
var myRoot = new Root
{
AParentProperty = "my AParentProperty",
TheNestedClass = new Nested
{
ANestedProperty = "my ANestedProperty"
}
};
// Manually create the mapper using the Profile
var mapper = new MapperConfiguration(cfg => cfg.AddProfile(new MappingProfile())).CreateMapper();
// ACT
var myFlattened = mapper.Map<Root, Flattened>(myRoot);
// ASSERT
Assert.Equal(myRoot.AParentProperty, myFlattened.AParentProperty);
Assert.Equal(myRoot.TheNestedClass.ANestedProperty, myFlattened.ANestedProperty);
}
[事实]
公共空心映射\u根\u到\u扁平\u应\u包括\u嵌套的\u属性()
{
//安排
var myRoot=新根
{
AParentProperty=“我的AParentProperty”,
TheNestedClass=新嵌套
{
ANestedProperty=“我的ANestedProperty”
}
};
//使用配置文件手动创建映射器
var mapper=new-MapperConfiguration(cfg=>cfg.AddProfile(new-MappingProfile()).CreateMapper();
//表演
var myflatted=mapper.Map(myRoot);
//断言
Assert.Equal(myRoot.AParentProperty、myflatted.AParentProperty);
Assert.Equal(myRoot.TheNestedClass.ANestedProperty、MyFlatted.ANestedProperty);
}
通过从自动添加AutoMapper的serviceCollection.AddAutoMapper()
Mapper.CreateMap<Root, Flattened>();
Mapper.CreateMap<Nested, Flattened>();
var flattened = new Flattened();
Mapper.Map(root, flattened);
Mapper.Map(root.TheNestedClass, flattened);
public class MappingProfile : Profile
{
public MappingProfile()
{
CreateMap<Root, Flattened>()
.AfterMap((src, dest, context) => context.Mapper.Map(src.TheNestedClass, dest));
CreateMap<Nested, Flattened>();
}
}
[Fact]
public void Mapping_root_to_flattened_should_include_nested_properties()
{
// ARRANGE
var myRoot = new Root
{
AParentProperty = "my AParentProperty",
TheNestedClass = new Nested
{
ANestedProperty = "my ANestedProperty"
}
};
// Manually create the mapper using the Profile
var mapper = new MapperConfiguration(cfg => cfg.AddProfile(new MappingProfile())).CreateMapper();
// ACT
var myFlattened = mapper.Map<Root, Flattened>(myRoot);
// ASSERT
Assert.Equal(myRoot.AParentProperty, myFlattened.AParentProperty);
Assert.Equal(myRoot.TheNestedClass.ANestedProperty, myFlattened.ANestedProperty);
}