EF Core Web API：外鍵驗證

Question

假設我有這些課程：

public class User
{
    public int? Id { get; set; }
    ...
}

public class Wallet
{
    public int? Id { get; set; }
    public string Title {get; set;}
    public User Owner { get; set; }
    ...
}

public class WalletCreationDTO 
{
    [Required]
    public string Title {get; set;}
    [Required]
    public int OwnerId { get; set; }
}

[HttpPost]
public async Task<ActionResult> CreateWallet(WalletCreationDto walletDTO) {...}

我必須像這樣向前端報告任何錯誤的參數：

{  
    "errors": {  
        "ownerId": "User by Id does not exist",  
        "title": "Must not exceed 8 characters"  
    }  
}

我如何 go 關於驗證 OwnerId？

• 手動查詢數據庫似乎無效
• 默認的 ASP.NET 核心驗證似乎沒有任何與數據庫訪問相關的注釋

Answer 1

我最終按照建議使用了流利的驗證。 這不是最有效的方法，但我正在權衡漂亮的錯誤和簡單的代碼。

public class WalletCreateDTO
{
    [Required]
    [MaxLength(20)]
    public string Title { get; set; }

    [Required]
    public int OwnerId { get; set; }

    [Required]
    public string CurrencyCode { get; set; }
}

public class WalletCreateDTOValidator : AbstractValidator<WalletCreateDTO>
{
    public WalletCreateDTOValidator(Data.Database database)
    {
        this.RuleFor(w => w.OwnerId)
            .Must(ownerId => database.Users.Any(user => user.Id == ownerId))
            .WithMessage("User does not exist");
        this.RuleFor(w=> w.CurrencyCode)
            .Must(currencyCode => database.Currencies.Any(currency => currency.Code == currencyCode))
            .WithMessage("Currency does not exist");
    }
}

--- To anyone reading this in the future ---

NuGet package： FluentValidation.AspNetCore

配置：

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers()
        .AddFluentValidation(config =>
        {
            config.RegisterValidatorsFromAssembly(typeof(WalletCreateDTO).Assembly);
        });
}

注意：這似乎注冊了程序集中的所有驗證器。 比如我所有的DTO都在Api.Dtos目錄/命名空間里，好像都注冊了，很方便。

此外，還有 swagger 集成： MicroElements.Swashbuckle.FluentValidation

Answer 2

您可以在簡單模式下使用它。

        [HttpPost]
        public async Task<ActionResult> CreateWallet(WalletCreationDto walletDTO)
        {
            bool isValidOwnerId = /*validationLogic => can use service or Repository or etc... */

            if (isValidOwnerId == false)
                ModelState.AddModelError("OwnerId", "errorMessage");


            if (ModelState.IsValid)
            {
                //CreateWallet Loigc......
            }

            //we can get all errors from ModelState
            List<ModelError> allErrors = ModelState.Values.SelectMany(v => v.Errors).ToList();

            /*
             return .... 
            */
        }

我還建議您閱讀以下兩個鏈接。

IValidatableObject

fluentvalidation ：流行的 .NET 庫，用於構建強類型驗證規則。