EF Core-使用Automapper从OData返回映射的多对多关系 [英] EF Core - Return mapped Many-to-Many relationship from OData using Automapper
问题描述
该应用程序类型是Hosted Blazor Web程序集。以下是我正在使用的nuget软件包的版本。尝试展开多对多关系的导航属性时，发生错误。这些类映射到展平中间关系类的DTO类。
The app type is a Hosted Blazor web-assembly. And below are the versions of the nuget packages I am using. There is an error that occurs when trying to expand a navigation property that is a many-to-many relationship. The classes are mapped to DTO classes that flattens the middle relationship class.
- .Net core Version = 3.1
- AutoMapper版本= 10.0.0
- AutoMapper.AspNetCore.OData.EFCore Version = 2.0.1
- AutoMapper .Extensions.ExpressionMapping Version = 4.0.1
- AutoMapper.Extensions.Microsoft.DependencyInjection Version = 8.0.1
- Microsoft .AspNetCore.Components.WebAssembly.Server Version = 3.2.1
- Microsoft.AspNetCore.OData Version = 7.5.0&
- .Net core Version="3.1"
- AutoMapper Version="10.0.0"
- AutoMapper.AspNetCore.OData.EFCore Version="2.0.1"
- AutoMapper.Extensions.ExpressionMapping Version="4.0.1"
- AutoMapper.Extensions.Microsoft.DependencyInjection Version="8.0.1"
- Microsoft.AspNetCore.Components.WebAssembly.Server Version="3.2.1"
- Microsoft.AspNetCore.OData Version="7.5.0"
要运行此存储库，您将需要SQL Server的免费版本或更高版本
To run this repo, you will need the free version of SQL Server or better
将EfCoreAutomapperOdata.Server项目设置为启动项目，然后导航到课程页面（https：// localhost：5001 / courses），然后单击任一课程。这将引发以下错误：
Set the EfCoreAutomapperOdata.Server project as the startup project and navigate to the Courses page (https://localhost:5001/courses) and click on either course. This will throw the following error:
System.InvalidOperationException：类型'Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions'上的通用方法'Include'与提供的类型参数兼容和争论。如果方法是非泛型的，则不应该提供任何类型参数。在System.Linq.Expressions.Expression.FindMethod（Type type，String methodName，Type [] typeArgs，Expression [] args，BindingFlags标志）...
public class AutomapperConfig : Profile
{
public AutomapperConfig()
{
CreateMap<Instructor, InstructorDto>();
CreateMap<InstructorDto, Instructor>();
CreateMap<Course, CourseDto>()
.ForMember(dto => dto.Students, opt => {
opt.MapFrom(_ => _.Students.Select(y => y.Student));
});
CreateMap<CourseDto, Course>()
.ForMember(ent => ent.Students, ex => ex
.MapFrom(x => x.Students.Select(y => new CourseStudent {
CourseId = x.Id,
StudentId = y.Id
})));
CreateMap<Student, StudentDto>()
.ForMember(dto => dto.Courses, opt => {
opt.MapFrom(x => x.Courses.Select(y => y.Course));
})
.ForMember(dto => dto.Friends, opt => {
opt.MapFrom(x => x.Friends.Select(y => y.Friend));
});
CreateMap<StudentDto, Student>()
.ForMember(ent => ent.Courses, ex => ex
.MapFrom(x => x.Courses.Select(y => new CourseStudent
{
StudentId = x.Id,
CourseId = y.Id
})));
}
}
启动
Startup
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
public void ConfigureServices(IServiceCollection services)
{
// ------ Some code removed for brevity ------
services.AddOData();
services.AddAutoMapper(cfg => { cfg.AddExpressionMapping(); },typeof(AutomapperConfig));
// ------ Some code removed for brevity ------
}
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
// ------ Some code removed for brevity ------
app.UseHttpsRedirection();
app.UseBlazorFrameworkFiles();
app.UseStaticFiles();
app.UseRouting();
app.UseEndpoints(endpoints =>
{
endpoints.MapRazorPages();
endpoints.MapControllers();
endpoints.EnableDependencyInjection();
endpoints.Select().Filter().OrderBy().Count().Expand().MaxTop(1000);
endpoints.MapODataRoute("odata", "odata", GetEdmModel());
endpoints.MapFallbackToFile("index.html");
});
}
private IEdmModel GetEdmModel()
{
var builder = new ODataConventionModelBuilder();
builder.EntitySet<CourseDto>("Courses");
builder.EntitySet<InstructorDto>("Instructors");
builder.EntitySet<StudentDto>("Students");
return builder.GetEdmModel();
}
}
课程负责人
Course Controller
public class CourseController : ODataController
{
protected readonly BlazorContext _context;
protected readonly IMapper _mapper;
public CourseController(BlazorContext context, IMapper mapper)
{
_context = context;
_mapper = mapper;
}
[HttpGet]
[ODataRoute("Courses")]
public async Task<IActionResult> Get(ODataQueryOptions<CourseDto> options)
{
return Ok(await _context.Course.GetAsync(_mapper, options));
}
[HttpGet]
[ODataRoute("Courses({id})")]
public async Task<IActionResult> Get([FromODataUri] int id, ODataQueryOptions<CourseDto> options)
{
return Ok((await _context.Course.GetAsync(_mapper, options)).Where(s => s.Id == id).ToList());
}
}
失败的示例odata api查询
/ odata / Courses？$ expand =学生
我已经为这个问题制作了演示Blazor WASM应用程序
I have built demo Blazor WASM app for this issue to reproduce
推荐答案
常规设置
要使扩展正常工作，您需要允许 $ expand 查询选项。像这样明确配置：
General Setup
To make expansions work, you need to allow for the $expand query option to be used. Configure it explicitly like so:
private IEdmModel GetEdmModel()
{
var builder = new ODataConventionModelBuilder();
builder.EntitySet<EstimateDto>(nameof(MyContext.Estimates))
.EntityType
.Expand(); // <-- allow expansion
builder.EntitySet<TypeDto>(nameof(MyContext.Types))
.EntityType
.Expand(); // <-- allow expansion
builder.EntitySet<SubTypeDto>(nameof(MyContext.SubTypes));
return builder.GetEdmModel();
}
您还需要更新AutoMapper映射，以使查询成功映射到DTO：
You will also need to update your AutoMapper map, to allow the queries to be successfully mapped to a DTOs:
public class AutoMapperConfig : Profile
{
public AutoMapperConfig()
{
CreateMap<Estimate, EstimateDto>()
.ForMember(
dto => dto.Types,
opt => opt.MapFrom(x => x.EstimateTypes.Select(y => y.Type)));
// The following mapping is needed for expansion to work:
CreateMap<EstimateTypeRel, TypeDto>()
.ForMember(
dto => dto.SubTypes,
opt => opt.MapFrom(x => x.Type));
CreateMap<Type, TypeDto>()
.ForMember(
dto => dto.SubTypes,
opt => opt.MapFrom(x => x.SubTypes.Select(y => y.SubType)));
CreateMap<SubTypeRel, SubTypeDto>();
}
}
设置该配置后，至少有两种可能的解决方案问题，具体取决于您的要求：
With that configuration being setup, there are at least two possible solutions to this issue, depending on your requirements:
如果仅要扩展 Types ，您需要通过添加来更改AutoMapper映射。where（z => z！= null）子句，因为异常告诉您，集合中不允许 null 值，但是OData包含未扩展的 SubType的值实体：
If you only want to expand Types, you will need to change your AutoMapper mappings by adding a .Where(z => z != null) clause, because as the exception tells you, null values are not allowed in collections, but OData includes them for the non-expanded SubType entities:
public class AutoMapperConfig : Profile
{
public AutoMapperConfig()
{
CreateMap<Estimate, EstimateDto>()
.ForMember(
dto => dto.Types,
opt => opt.MapFrom(
x => x.EstimateTypes.Select(y => y.Type)
.Where(z => z != null))); // <-- filter out null values
CreateMap<EstimateTypeRel, TypeDto>()
.ForMember(
dto => dto.SubTypes,
opt => opt.MapFrom(x => x.Type));
CreateMap<Type, TypeDto>()
.ForMember(
dto => dto.SubTypes,
opt => opt.MapFrom(
x => x.SubTypes.Select(y => y.SubType)
.Where(z => z != null))); // <-- filter out null values
CreateMap<SubTypeRel, SubTypeDto>();
}
}
然后您可以使用以下查询：
Then you can use the following query:
https://localhost:5001/odata/Estimates(1)?$expand=Types
B）同时扩展 SubTypes
另一种方法是扩展 SubTypes 属性，因此可以正确填充集合。要将DTO映射的属性扩展到多个级别，请在查询字符串中使用 $ expand 查询选项，如下所示：
B) Also expand SubTypes
The alternative is to expand the SubTypes property as well, so the collection can be properly filled. To expand DTO mapped properties over multiple levels, use the $expand query option in your query string like so:
https://localhost:5001/odata/Estimates(1)?$expand=Types($expand=SubTypes)
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