插入后映射外键对象

Question

插入新记录时，要求返回一个 DTO，其中包含在预期输出中的简化 FK 对象或完整 FK 对象。

问题是相关对象 ExampleOptionDto 和 ExampleOptionSimpleDto 总是为空。

我做错了什么？

// 预期输出

{
    "Id": 45,
    "Name": "Example...",
    "ExampleOptionSimple": {
        "Id": 45,
        "Name": "Example Option 7"
    },
    "ExampleOption": {
        "Id": 45,
        "Name": "Example Option 7",
        "Acronym": "",
        ...
    }
}

// 创建处理程序

public class Create
{
    public class Command : IRequest<ExampleDto>
    {
        public string Name { get; set; }
        public int ExampleOptionId { get; set; }
    }

    public class Handler : BaseHandler, IRequestHandler<Command, ExampleDto>
    {
        public Handler(ApplicationContext db, IMapper mapper, IUserContext userContext) : base(db, mapper, userContext) {}

        public async Task<ExampleDto> Handle(Command command, CancellationToken cancellationToken)
        {
            ExampleEntity entity = Mapper.Map<Command, ExampleEntity>(command);
            await Db.ExampleEntity.AddAsync(entity, cancellationToken);
            await Db.SaveChangesAsync(cancellationToken);
            
            ExampleDto model = Mapper.Map<ExampleEntity, ExampleDto>(entity);
            return model;
        }
    }
}

// DTO

public class ExampleDto
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int ExampleOptionId { get; set; }

    // Use this to return a simple related model with just Id & Name
    public ExampleOptionSimpleDto ExampleOptionSimple { get; set; }

    // Use this to return the full related object and all properties
    public ExampleOptionDto ExampleOption { get; set; }
}

public class ExampleOptionDto
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Acronym { get; set; }
    public int SortOrder { get; set; }
    public bool IsActive { get; set; }
    public Guid? DeletedBy { get; set; }
}

public class ExampleOptionSimpleDto
{
    public int Id { get; set; }
    public string Name { get; set; }
}

// 映射

CreateMap<ExampleOption, ExampleOptionSimpleDto>();
CreateMap<ExampleOption, ExampleOptionDto>();
CreateMap<ExampleEntity, ExampleDto>();

// 测试

[Theory]
[ClassData(typeof(CreateTestData))]
public async Task Create_Adds_Record_To_Store_And_Returns_It(Create.Command cmd)
{
    // Create a new record
    ExampleDto exampleDto = await _fixture.SendAsync(cmd, _accessor);
    exampleDto.ShouldNotBeNull(); // Passes
    exampleDto.Id.ShouldBe(1); // Passes
    
    exampleDto.ExampleOption.ShouldNotBeNull(); // Fails
    exampleDto.ExampleOptionSimple.ShouldNotBeNull(); // Fails
}

Answer 1

你写的一切对我来说都很有意义，我只有两个建议

1) 调试你的命令处理程序。具体来说，这里的每个值都存储了什么

ExampleEntity entity = Mapper.Map<Command, ExampleEntity>(command);
await Db.ExampleEntity.AddAsync(entity, cancellationToken);
await Db.SaveChangesAsync(cancellationToken);
        
ExampleDto model = Mapper.Map<ExampleEntity, ExampleDto>(entity);

2. 尝试添加另一个从 dto 到实体的映射

CreateMap<ExampleDto ,ExampleEntity>();