Automapper 5.2(当前最新)如果在Base Data Transfer Object的映射中配置,则忽略ExplicitExpansion()配置.但是,如果直接在Derived DTO中配置了映射,它仍然可以正常工作.我有一对DTO类,它们在字段集和映射配置中包含很多重复,我试图将它隔离到公共基础DTO类,但是这个问题阻止了我这样做.
下面的代码说明了这种奇怪的行为.有四个测试,其中两个未能断言未扩展基础DTO的属性.如果我将1-1..1-4行移动到2.1,则所有测试都通过.
我是否错过了一些代码或者这是Automapper中的错误,我必须向Automapper的错误跟踪器报告此问题？或者它可能是“按设计”,但为什么呢？ (Ivan Stoev提出了一个有效的解决方案,但请允许我推迟接受答案,因为我面临的问题不是那么简单,我在下面的更新中添加了更多细节).
的UnitTest1.cs：
using System.Collections.Generic;
using System.Linq;
using AutoMapper;
using AutoMapper.QueryableExtensions;
using Microsoft.VisualStudio.TestTools.UnitTesting;
namespace AutoMapperIssue
{
public class Source { public string Name; public string Desc; }
public class DtoBase { public string Name { get; set; } }
public class DtoDerived : DtoBase { public string Desc { get; set; } }
[TestClass] public class UnitTest1
{
[AssemblyInitialize] public static void AssemblyInit(TestContext context)
{
Mapper.Initialize(cfg =>
{
cfg.CreateMap<Source,DtoBase>()
.ForMember(dto => dto.Name,conf => { // line 1-1
conf.MapFrom(src => src.Name); // line 1-2
conf.ExplicitExpansion(); // line 1-3
}) // line 1-4
.Include<Source,DtoDerived>();
cfg.CreateMap<Source,DtoDerived>()
// place 2.1
.ForMember(dto => dto.Desc,conf => {
conf.MapFrom(src => src.Desc);
conf.ExplicitExpansion();
});
});
Mapper.Configuration.CompileMappings();
Mapper.AssertConfigurationIsValid();
}
private readonly IQueryable<Source> _iq = new List<Source> {
new Source() { Name = "Name1",Desc = "Descr",},} .AsQueryable();
[TestMethod] public void ProjectAll_Success()
{
var projectTo = _iq.ProjectTo<DtoDerived>(_ => _.Name,_ => _.Desc);
Assert.AreEqual(1,projectTo.Count()); var first = projectTo.First();
Assert.IsNotNull(first.Desc); Assert.AreEqual("Descr",first.Desc);
Assert.IsNotNull(first.Name); Assert.AreEqual("Name1",first.Name);
}
[TestMethod] public void SkipDerived_Success()
{
var projectTo = _iq.ProjectTo<DtoDerived>(_ => _.Name);
Assert.AreEqual(1,projectTo.Count()); var first = projectTo.First();
Assert.IsNotNull(first.Name); Assert.AreEqual("Name1",first.Name);
Assert.IsNull(first.Desc,"Should not be expanded.");
}
[TestMethod] public void SkipBase_Fail()
{
var projectTo = _iq.ProjectTo<DtoDerived>(_ => _.Desc);
Assert.AreEqual(1,first.Desc);
Assert.IsNull(first.Name,"Should not be expanded. Fails here. Why?");
}
[TestMethod] public void SkipAll_Fail()
{
var projectTo = _iq.ProjectTo<DtoDerived>();
Assert.AreEqual(1,projectTo.Count()); var first = projectTo.First();
Assert.IsNull(first.Desc,"Should not be expanded.");
Assert.IsNull(first.Name,"Should not be expanded. Fails here. Why?");
}
}
}
packages.config：
<package id="AutoMapper" version="5.2.0" targetFramework="net452" />
UPD. Ivan Stoev全面回答了如何解决上面编码的问题.除非我被迫使用字段名称的字符串数组而不是MemberExpressions,否则它的效果非常好.这与这种方法与Value类型的成员(例如int,int？)崩溃有关.在下面的第一个单元测试中演示了崩溃堆栈跟踪.我会在另一个问题中询问它,或者更确切地说是在bug跟踪器中创建一个问题,因为崩溃肯定是一个bug.
UnitTest2.cs – 修复了Ivan Stoev的回答
using System;
using System.Collections.Generic;
using System.Linq;
using AutoMapper;
using AutoMapper.QueryableExtensions;
using Microsoft.VisualStudio.TestTools.UnitTesting;
namespace AutoMapperIssue.StringPropertyNames
{ /* int? (or any ValueType) instead of string - .ProjectTo<> crashes on using MemberExpressions in projction */
using NameSourceType = Nullable<int> /* String */; using NameDtoType = Nullable<int> /* String */;
using DescSourceType = Nullable<int> /* String */; using DescDtoType = Nullable<int> /* String*/;
public class Source
{
public NameSourceType Name { get; set; }
public DescSourceType Desc { get; set; }
}
public class DtoBase { public NameDtoType Name { get; set; } }
public class DtoDerived : DtoBase { public DescDtoType Desc { get; set; } }
static class MyMappers
{
public static IMappingExpression<TSource,TDestination> Configure<TSource,TDestination>(this IMappingExpression<TSource,TDestination> target)
where TSource : Source
where TDestination : DtoBase
{
return target.ForMember(dto => dto.Name,conf =>
{
conf.MapFrom(src => src.Name);
conf.ExplicitExpansion();
});
}
}
[TestClass] public class UnitTest2
{
[ClassInitialize] public static void ClassInit(TestContext context)
{
Mapper.Initialize(cfg =>
{
cfg.CreateMap<Source,DtoBase>()
.Configure()
.Include<Source,DtoDerived>()
.Configure()
.ForMember(dto => dto.Desc,conf => {
conf.MapFrom(src => src.Desc);
conf.ExplicitExpansion();
})
;
});
Mapper.Configuration.CompileMappings();
Mapper.AssertConfigurationIsValid();
}
private static readonly IQueryable<Source> _iq = new List<Source> {
new Source() { Name = -25 /* "Name1" */,Desc = -12 /* "Descr" */,} .AsQueryable();
private static readonly Source _iqf = _iq.First();
[TestMethod] public void ProjectAllWithMemberExpression_Exception()
{
_iq.ProjectTo<DtoDerived>(_ => _.Name,_ => _.Desc); // Exception here,no way to use Expressions with current release
//Test method AutoMapperIssue.StringPropertyNames.UnitTest2.ProjectAllWithMemberExpression_Exception threw exception:
//System.NullReferenceException: Object reference not set to an instance of an object.
//
// at System.Linq.Enumerable.<SelectManyIterator>d__16`2.MoveNext()
// at System.Linq.Enumerable.<distinctIterator>d__63`1.MoveNext()
// at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
// at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
// at AutoMapper.QueryableExtensions.ProjectionExpression.To[TResult](IDictionary`2 parameters,IEnumerable`1 memberPathsToExpand)
// at AutoMapper.QueryableExtensions.ProjectionExpression.To[TResult](Object parameters,Expression`1[] membersToExpand)
// at AutoMapper.QueryableExtensions.Extensions.ProjectTo[TDestination](IQueryable source,IConfigurationProvider configuration,Object parameters,Expression`1[] membersToExpand)
// at AutoMapperIssue.StringPropertyNames.UnitTest2.ProjectAllWithMemberExpression_Exception() in D:\01\AutoMapperIssue\UnitTest2.cs:line 84
}
#pragma warning disable 649
private DtoDerived d;
#pragma warning restore 649
[TestMethod] public void ProjectAll_Fail()
{
var projectTo = _iq.ProjectTo<DtoDerived>(null,new string[] { nameof(d.Name),nameof(d.Desc) } /* _ => _.Name,_ => _.Desc */);
Assert.AreEqual(1,projectTo.Count()); var first = projectTo.First();
Assert.IsNotNull(first.Desc,"Should be expanded."); Assert.AreEqual(_iqf.Desc,first.Desc);
Assert.IsNotNull(first.Name,"Should be expanded. Fails here,why?"); Assert.AreEqual(_iqf.Name,first.Name);
}
[TestMethod] public void BaSEOnly_Fail()
{
var projectTo = _iq.ProjectTo<DtoDerived>(null,new string[] { nameof(d.Name) } /* _ => _.Name */);
Assert.AreEqual(1,"Should NOT be expanded.");
Assert.IsNotNull(first.Name,first.Name);
}
[TestMethod] public void DerivedOnly_Success()
{
var projectTo = _iq.ProjectTo<DtoDerived>(null,new string[] { nameof(d.Desc) } /* _ => _.Desc */);
Assert.AreEqual(1,"Should be expanded."); Assert.AreEqual(_iqf.Desc,"Should NOT be expanded.");
}
[TestMethod] public void SkipAll_Success()
{
var projectTo = _iq.ProjectTo<DtoDerived>(null,new string[] { });
Assert.AreEqual(1,"Should NOT be expanded.");
Assert.IsNull(first.Name,"Should NOT be expanded.");
}
}
}
UPD2.上面更新的问题肯定无法在外面修复,请参阅接受的答案下的评论.这是AutoMapper本身的问题.如果您迫不及待地想要修复更新的问题,可以使用以下简单(但不是次要)差异来制作AutoMapper补丁：https://github.com/moudrick/AutoMapper/commit/65005429609bb568a9373d7f3ae0a535833a1729
解决方法
Have I missed some piece of code
你没有错过任何东西.
or is this a bug in Automapper and I have to report this issue to Automapper’s bug tracker? Or is it probably “by design”,but why?
我怀疑这是“按设计”,很可能是错误或不完整的快速和脏实施.可以在PropertyMap类的ApplyInheritedPropertyMap方法的source code内部看到,该方法负责组合基本属性和派生属性配置. “继承的”映射属性目前是：
> CustomExpression
> Customresolver
>条件
>前提条件
> NullSubstitute
> MappingOrder
> ValueResolverConfig
而以下(基本上所有bool类型)属性(包括有问题的属性)不是：
> AllowNull
> UseDestinationValue
> ExplicitExpansion
IMO的问题是当前的实现无法确定是否明确设置了bool属性.当然,通过用显式bool替换auto属性可以很容易地解决它？支持字段和默认值逻辑(以及其他流畅的配置方法,以便在基类配置中打开它时将其关闭).不幸的是,它只能在源代码中完成,因此我建议您将问题报告给他们的问题跟踪器.
直到(以及如果)他们修复它,我可以建议将所有常用代码移动到自定义扩展方法,如
static class MyMappers
{
public static IMappingExpression<TSource,TDestination> target)
where TSource : Source
where TDestination : DtoBase
{
return target
.ForMember(dto => dto.Name,conf =>
{
conf.MapFrom(src => src.Name);
conf.ExplicitExpansion();
});
}
}
并从主配置代码中使用它们：
Mapper.Initialize(cfg =>
{
cfg.CreateMap<Source,DtoBase>()
.Configure();
cfg.CreateMap<Source,DtoDerived>()
.Configure()
.ForMember(dto => dto.Desc,conf => {
conf.MapFrom(src => src.Desc);
conf.ExplicitExpansion();
});
});
编辑：关于其他问题.两者都是更严重的AM处理错误,与配置无关.
问题是他们尝试使用MemberInfo实例比较来过滤投影.
第一种情况(带表达式)对于值类型失败,因为尝试从Expression< Func< T,object>>中提取MemberInfo的实现我只期待MemberExpression,但是在值类型的情况下,它包含在Expression.Convert中.
第二种情况(带有属性名称)失败,因为他们没有考虑这样的事实：从编译时lambda表达式中提取的基类继承的属性的MemberInfo与反射或运行时创建的表达式检索的属性不同,这与以下测试：
// From reflection var nameA = typeof(DtoDerived).GetMember(nameof(DtoDerived.Name)).Single(); // Same as //var nameA = typeof(DtoDerived).GetProperty(nameof(DtoDerived.Name)); // From compile time expression Expression<Func<DtoDerived,NameDtoType>> compileTimeExpr = _ => _.Name; var nameB = ((MemberExpression)compileTimeExpr.Body).Member; // From runtime expression var runTimeExpr = Expression.PropertyOrField(Expression.Parameter(typeof(DtoDerived)),nameof(DtoDerived.Name)); var nameC = runTimeExpr.Member; Assert.AreEqual(nameA,nameC); // Success Assert.AreEqual(nameA,nameB); // Fail
你肯定需要报告这两个问题.我会说,在提供表达式列表时,任何值类型属性都会泄露该功能,并且在提供名称时,任何继承的属性都会泄露.