.Net Core3.0 WEB API 中使用FluentValidation驗證，實現批量注入

為什么要使用FluentValidation

1.在日常的開發中，需要驗證參數的合理性，不緊前端需要驗證傳毒的參數，后端也需要驗證參數 2.在領域模型中也應該驗證,做好防御性的編程是一種好的習慣（其實以前重來不寫的，被大佬教育了一番） 3.FluentValidation 是.NET 開發的驗證框架，開源,主要是簡單好用，內置了一些常用的驗證器，可以直接使用，擴展也很方便

使用FluentValidation

1.引入FluentValidation.AspNetCore NuGet包 2.建立需要驗證的類

/// <summary>
/// 創建客戶
/// </summary>
public class CreateCustomerDto
{
    /// <summary>
    /// 客戶姓名
    /// </summary>
    public string CustomerName { get; set; }
    /// <summary>
    /// 客戶年齡
    /// </summary>
    public string CustomerAge { get; set; }
    /// <summary>
    /// 客戶電話
    /// </summary>
    public string CustomerPhone { get; set; }
    /// <summary>
    /// 客戶地址
    /// </summary>
    public Address CustomerAddress { get; set; }
}

/// <summary>
/// 驗證
/// </summary>
public class CreateCustomerDtoValidator : AbstractValidator<CreateCustomerDto>
{
    public CreateCustomerDtoValidator()
    {
        RuleFor(x => x.CustomerName)
              .NotEmpty()
              .WithMessage("客戶姓名不能為空");
        RuleFor(x => x.CustomerPhone)
              .NotEmpty()
              .WithMessage("客戶電話不能為空");

    }
}

3.統一返回驗證的信息，ResponseResult為全局統一參數返回的類

    /// <summary>
    /// 添加AddFluentValidationErrorMessage
    /// </summary>
    /// <returns></returns>
    public DependencyInjectionService AddFluentValidationErrorMessage()
    {
        _services.Configure<ApiBehaviorOptions>(options =>
        {
            options.InvalidModelStateResponseFactory = (context) =>
            {
                var errors = context.ModelState
                    .Values
                    .SelectMany(x => x.Errors
                                .Select(p => p.ErrorMessage))
                    .ToList();
                var result = new ResponseResult<List<string>>
                {
                    StatusCode = "00009",
                    Result = errors,
                    Message = string.Join(",", errors.Select(e => string.Format("{0}", e)).ToList()),
                    IsSucceed = false
                };

                return new BadRequestObjectResult(result);
            };
        });
        return _dependencyInjectionConfiguration;
    }

4.注入驗證的類 使用builder.RegisterType ().As >();比較麻煩每次新增都需要添加一次注入 所以我們使用批量的注入，來減少麻煩,通過反射獲取所有的驗證的類批量注入

    /// <summary>
    /// 添加MVC
    /// </summary>
    /// <returns></returns>
    public DependencyInjectionService AddMvc()
    {
        _services.AddControllers(options => 
        { 
            options.Filters.Add(typeof(LogHelper));
        }).AddJsonOptions(options =>
        {
            //忽略循環引用
            //options.JsonSerializerOptions.IgnoreReadOnlyProperties = true;
        }).AddFluentValidation(options =>
        {
            options.RunDefaultMvcValidationAfterFluentValidationExecutes = false;
            var validatorList = GetFluentValidationValidator("ConferenceWebApi");
            foreach (var item in validatorList)
            {
                options.RegisterValidatorsFromAssemblyContaining(item);
            }
        });
        return _dependencyInjectionConfiguration;
    }

    /// <summary>
    /// 獲取所有的FluentValidation Validator的類
    /// </summary>
    public IEnumerable<Type> GetFluentValidationValidator(string assemblyName)
    {
        if (assemblyName == null)
            throw new ArgumentNullException(nameof(assemblyName));
        if (string.IsNullOrEmpty(assemblyName))
            throw new ArgumentNullException(nameof(assemblyName));

        var implementAssembly = RuntimeHelper.GetAssembly(assemblyName);
        if (implementAssembly == null)
        {
            throw new DllNotFoundException($"the dll ConferenceWebApi not be found");
        }
        var validatorList = implementAssembly.GetTypes().Where(e => e.Name.EndsWith("Validator"));
        return validatorList;
    }

5.使用起來就十分簡單了

    /// <summary>
    /// 創建客戶
    /// </summary>
    /// <param name="input"></param>
    /// <returns></returns>
    [HttpPost]
    public async Task<ResponseResult<string>> CreateCustomer([FromBody] CreateCustomerDto input)
    {
        var createCustomerCommand = new CreateCustomerCommand(input.CustomerName,input.CustomerAge,input.CustomerPhone,input.CustomerAddress);
        await _commandService.SendCommandAsync(createCustomerCommand);
        var result = new ResponseResult<string>
        {
            IsSucceed = true,
            Result = "創建客戶成功！"
        };
        return result;
    }

FluentValidation學習的資料

感謝大佬們的分享，零度編程中的教程非常的全面，包括了許多的驗證器的使用，記不住時直接可以翻閱查看 零度編程：https://www.xcode.me/post/5849 Lamond Lu：https://www.cnblogs.com/lwqlun/p/10311945.html