.Net Core Dto映射(AutoMapper)

我們假設一個場景, 採用EF Core+Web Api, 這時候可能會出現EF Core中的Entity Model和在項目中使用的Model之間對應關係出現偏差, 如果使用屬性意一一對應, 不免會有大量的工作量, 上代碼

EntityModels.Employee.cs

public class Employee
{
    public Guid Id { get; set; }
    public Guid CompanyId { get; set; }

    public string EmployeeNo { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public Gender Gender { get; set; }
    public DateTime DateOfBirth { get; set; }

    public Company Company { get; set; }
}

Models.EmployeeDto.cs

public class EmployeeDto
{
    public Guid Id { get; set; }
    public Guid CompanyId { get; set; }

    public string EmployeeNo { get; set; }
    public string Name { get; set; }
    public string GenderDisplay { get; set; }
    public int Age { get; set; }
}

我們可以觀察到, 兩個實體之間有很多不同的地方, 比如名字拆分啊, 出生日期和年齡啊等等, 我之前的做法就是硬生生手寫代碼轉換, 但是經過學習大佬們的代碼, 發現了一個類庫, 在此算是記錄一下吧

AutoMapper.Extensions.Microsoft.DependencyInjection

可以通過NuGet安裝

使用的時候也非常簡單, 建立Profile文件夾, 新建一個EmployeeProfile類, 繼承於Profile

public class EmployeeProfile: Profile
{
    public EmployeeProfile()
    {
        CreateMap<Employee, EmployeeDto>()
            .ForMember(dest => dest.Name,
                opt => opt.MapFrom(src => $"{src.FirstName} {src.LastName}"))
            .ForMember(dest => dest.GenderDisplay,
                opt => opt.MapFrom(src => src.Gender.ToString()))
            .ForMember(dest => dest.Age,
                opt => opt.MapFrom(src => DateTime.Now.Year - src.DateOfBirth.Year));
    }
}

在使用的時候只需要這樣, 註入mapper, 然後就是很簡單的操作了, 簡直了, 功能非常強大!!!

[ApiController]
[Route("api/companies/{companyId}/employees")]
public class EmployeesController: ControllerBase
{
    private readonly IMapper _mapper;
    private readonly ICompanyRepository _companyRepository;

    public EmployeesController(IMapper mapper, ICompanyRepository companyRepository)
    {
        _mapper = mapper ?? throw new ArgumentNullException(nameof(mapper));
        _companyRepository = companyRepository ?? throw new 
            ArgumentNullException(nameof(companyRepository));
    }
    [HttpPost]
    public async Task<ActionResult<EmployeeDto>>
        CreateEmployeeForCompany(Guid companyId, EmployeeAddDto employee)
    {
        if (!await _companyRepository.CompanyExistsAsync(companyId))
        {
            return NotFound();
        }

        var entity = _mapper.Map<Employee>(employee);

        _companyRepository.AddEmployee(companyId, entity);
        await _companyRepository.SaveAsync();

        var dtoToReturn = _mapper.Map<EmployeeDto>(entity);

        return CreatedAtRoute(nameof(GetEmployeeForCompany), new
        {
            companyId = companyId,
            employeeId = dtoToReturn.Id
        }, dtoToReturn);
    }
}