具有Linq OrderBy子属性错误的自动映射器投影 [英] Automapper Projection with Linq OrderBy child property error

问题描述

使用AutoMapper(版本5.1.1)投影与Linq OrderBy Child属性表达式结合使用时出现问题.我正在使用Entity Framework Core(版本1.0.0).我收到以下错误:

I am having an issue using an AutoMapper (version 5.1.1) projection combined with a Linq OrderBy Child property expression. I am using Entity Framework Core (version 1.0.0). I am getting the following error:

必须是可还原节点"

"must be reducible node"

我的DTO对象如下

public class OrganizationViewModel
    {
        public virtual int Id { get; set; }
        [Display(Name = "Organization Name")]
        public virtual string Name { get; set; }
        public virtual bool Active { get; set; }
        public virtual int OrganizationGroupId { get; set; }
        public virtual string OrganizationGroupName { get; set; }
        public virtual int StrategyId { get; set; }
        public virtual string StrategyName { get; set; }
        public virtual OrganizationGroupViewModel OrganizationGroup { get; set; }
    }

public class OrganizationGroupViewModel
    {
        public virtual int Id { get; set; }
        [Display(Name = "Organization Group Name")]
        public virtual string Name { get; set; }
        public virtual bool Active { get; set; }
    }

我对应的实体模型如下:

My corresponding entity models are as follows:

public class Organization
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string TimeZone { get; set; }
        public bool Active { get; set; }
        //FKs
        public int OrganizationGroupId { get; set; }
        public int StrategyId { get; set; }
        //Navigation
        public virtual OrganizationGroup OrganizationGroup { get; set; }
        public virtual Strategy Strategy { get; set; }
        [JsonIgnore]
        public virtual List<AppointmentReminder> AppointmentReminders { get; set; }
    }

public class OrganizationGroup
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public bool Active { get; set; }

        public virtual List<Organization> Organizations { get; set; }
    }

我的AutoMapper配置文件如下:

My AutoMapper profiles are as follows:

public class OrganizationMapperProfile : Profile
    {
        public OrganizationMapperProfile()
        {
            CreateMap<Task<Organization>, Task<OrganizationViewModel>>();
            CreateMap<Organization, OrganizationViewModel>()
                .ForMember(dest => dest.OrganizationGroupName, opt => opt.MapFrom(src => src.OrganizationGroup.Name));
            CreateMap<OrganizationInput, Organization>()
                .ForMember(x => x.Id, opt => opt.Ignore());
        }
    }

public class OrganizationGroupMapperProfile : Profile
    {
        public OrganizationGroupMapperProfile()
        {
            CreateMap<Task<OrganizationGroup>, Task<OrganizationGroupViewModel>>();
            CreateMap<OrganizationGroup, OrganizationGroupViewModel>();
            CreateMap<OrganizationGroupInput, OrganizationGroup>()
                .ForMember(x => x.Id, opt => opt.Ignore());
        }
    }

运行以下语句时，我可以运行并从前两个语句中获取结果:

When I run the following statements I am able to run and get results from the first 2 statements:

var tmp = await _context.Organizations.Include(x => x.OrganizationGroup).OrderBy(x => x.OrganizationGroup.Name).ToListAsync();
var tmp4 = await _context.Organizations.Include(x => x.OrganizationGroup).OrderBy("OrganizationGroup.Name").ToListAsync();

但是当我添加ProjectTo时，出现上面列出的错误:

But when I add the ProjectTo I get the error listed above:

var tmp5 = await _context.Organizations.Include(x => x.OrganizationGroup).OrderBy(x => x.OrganizationGroup.Name).ProjectTo<OrganizationViewModel>().ToListAsync();
var tmp6 = await _context.Organizations.Include(x => x.OrganizationGroup).OrderBy("OrganizationGroup.Name").ProjectTo<OrganizationViewModel>().ToListAsync();

作为一些其他信息，我能够与Projection一起对父类的属性进行排序，例如:

As some additional information, I am able to OrderBy with Projections working on properties of the parent class, such as:

var tmp7 = await _context.Organizations.Include(x => x.OrganizationGroup).OrderBy(x => x.Name).ProjectTo<OrganizationViewModel>().ToListAsync();
var tmp8 = await _context.Organizations.Include(x => x.OrganizationGroup).OrderBy("Name").ProjectTo<OrganizationViewModel>().ToListAsync();

有人遇到过这个问题吗?看起来我正在尝试执行本来不支持的操作，这是设计使然吗?感谢您的帮助/见解.

Anyone run into this issue before? Looks like I'm trying to do something that is otherwise not supported, is that by design? Thanks for any help/insight.

推荐答案

问题似乎是由OrganizationViewModel类的OrganizationGroup属性引起的-AutoMapper会生成EF Core不喜欢的null检查.与您的OrderBy结合使用(我想只是EF Core中目前存在的许多错误之一).可以通过以下简单的手动投影查询轻松重现它:

Looks like the problem is caused by the OrganizationGroup property of the OrganizationViewModel class - AutoMapper generates a null check which EF Core doesn't like in the combination with your OrderBy (I guess just one of the many bugs currently in EF Core). It can easily be reproduced by the following simple manual projection query:

var tmp5a = _context.Organizations
    .OrderBy(x => x.OrganizationGroup.Name)
    .Select(e => new OrganizationViewModel
    {
        Id = e.Id,
        OrganizationGroup = e.OrganizationGroup != null ? new OrganizationGroupViewModel
        {
             Id = e.OrganizationGroup.Id,
             Name = e.OrganizationGroup.Name,
             Active = e.OrganizationGroup.Active,
        } : null,
    })
    .ToList();

要解决此问题，请配置AutoMapper使其不生成null检查该属性，如下所示:

To fix the issue, configure AutoMapper to not generate null check for that property as follows:

CreateMap<Organization, OrganizationViewModel>()
    .ForMember(dest => dest.OrganizationGroup, opt => opt.AllowNull())
    .ForMember(dest => dest.OrganizationGroupName, opt => opt.MapFrom(src => src.OrganizationGroup.Name));

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