c# - 如何在 WebAPI 的 Controller 中使用 DTO？

Question

我对如何在我的 WebAPI Controller 中使用 DTO 感到有点困惑。我正在使用 Entity Framework 的数据库优先概念。生成了以下实体数据模型:

//Generated class by EDM:
public partial class Address
    {
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
        public Address()
        {
            this.Member = new HashSet<Member>();
        }

        public int Id { get; set; }
        public string Street { get; set; }
        public Nullable<short> Street_Number { get; set; }
        public Nullable<decimal> Zip { get; set; }
        public string City { get; set; }
        public string Country { get; set; }

        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
        public virtual ICollection<Member> Member { get; set; }
    }

要使用数据注释，我需要定义一个 AddressDTO，因为每次我需要修改 EDM 时，数据模型都会再次生成，数据注释就会丢失。

接下来，我定义了 AddressDTO:

public class AddressDTO
    {
        public int Id { get; set; }
        [Required]
        [StringLength(100,ErrorMessage="The max. length of the street name is 100 characters.")]
        public string Street { get; set; }
        public Nullable<short> Street_Number { get; set; }
        [Required]
        public Nullable<decimal> Zip { get; set; }
        [Required]
        [RegularExpression(@"[a-z,A-Z]",ErrorMessage="Only characters are allowed.")]
        public string City { get; set; }
        [Required]
        public string Country { get; set; }
    }

Controller 看起来像下面的代码:

    [RoutePrefix("api/address")]
    public class AddressController : ApiController
    {
        private PersonEntities db = new PersonEntities();

        // GET: api/Address
        [HttpGet]
        [ResponseType(typeof(AddressDTO))]
        public async Task<IHttpActionResult> GetAll()
        {
            var addressList = await db.Address.ToListAsync();

            return Ok(addressList);
        }
     }

当我启动 RestAPI 以在浏览器中显示结果时，我总是得到以下 json 结果:

[
    {
        "Member": [ ],
        "Id": 1,
        "Street": "Example Street",
        "Street_Number": 1,
        "Zip": 12345.0,
        "City": "New York",
        "Country": "USA" 
    },...
]

但我需要以下预期结果:

[
        {
            "Street": "Example Street",
            "Street_Number": 1,
            "Zip": 12345.0,
            "City": "New York",
            "Country": "USA" 
        },...
    ]

有人知道我该如何解决吗？

Answer 1

您的新编辑仅意味着您不需要 Id和 Member AddressDTO 中的属性模型。你应该将结果塑造成 List<AddressDTO>当你回来的时候List<Address> .

因此只需从 AddressDTO 中删除未使用的属性即可然后通过选择新的 AddressDTO 来塑造结果和设置属性:

var result = db.Address.Select(x=> new AddressDTO()
                                   { 
                                       Street = x.Id, 
                                       Street_Number = x.Street_Number,
                                       City = x.City,
                                       Country = x.Country
                                   }).ToListAsync();

如果你想让 linq 更短，你可以将这样的构造函数添加到 AddressDTO :

public AddressDTO(Address x)
{
    Street = x.Id;
    Street_Number = x.Street_Number;
    City = x.City;
    Country = x.Country;
}

然后在 Controller 中:

var result = db.Address.Select(x=> new AddressDTO(x)).ToListAsync();

同样在大型项目中，您可以依赖一些对象映射器，如答案中提到的自动映射器。