ASP.NET Core WebApi Post/IValidatableObjext/添加类级别验证/自定义错误报告

Post 从body提交（json或其他格式）

  [HttpPost]
        public async Task<ActionResult<CompanyDto>> CreateCompany([FromBody] CompanyAddDto companyAddDto)
        {
            var entity = _mapper.Map<Company>(companyAddDto);
            _companyRepository.AddCompany(entity);//执行到这里仅仅提交到了DbContext，还没有保存到数据库
            await _companyRepository.saveAsync();
            var dot = _mapper.Map<CompanyDto>(entity);
            //创建成功定位到GetCompanie方法上，传入值
            return CreatedAtRoute(nameof(GetCompanie), routeValues: new { companyId = dot.Id }, dot);
        }

实现IValidatableObjext接口添加自定义验证

 [CompanyNameMustLessThanNighteenAttribute]
    public class CompanyAddDto:IValidatableObject
    {
        //ID不需要的，它要在api后台自动生成，当然客户端提供也是可以的
        //公司类，公司输出类，公司添加类，分别创建（便于以后改动！）
        [Display(Name="Company Name!")]
        [Required(ErrorMessage ="{0} is Required!!!!!")] //{0} is name
        public string Name { get; set; }
        public string Introduction { get; set; }

        //add user Validation with complex 
        public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
        {
            if (Name.Length >= 15)
            {
                yield return new ValidationResult(errorMessage: "Errormsg", memberNames: new[] { nameof(Name) });
            }
        }

        //the other validation : FluentValidation(recommendation)
        //1.easy create complex validation
        //2.validation rules seprate form Model
        //3.to unit Test
        
    }

添加类级别的验证
类前面添加[CompanyNameMustLessThanNighteenAttribute]
实现ValidationAttribute

  //Define user's Validation for Class Level
    public class CompanyNameMustLessThanNighteenAttribute:ValidationAttribute
    {
        protected override ValidationResult IsValid(object value, ValidationContext validationContext)
        {
            var addDto = value as CompanyAddDto;//another method:validationContext.ObjectInstance
            if (addDto.Name.Length >= 15)
            {
                return new ValidationResult(errorMessage: "名字太长了");
            }
            return ValidationResult.Success;
        }
    }

自定义错误信息和错误报告.ConfigureApiBehaviorOptions

 services.AddControllers(
                configure: setup =>
                {
                    setup.ReturnHttpNotAcceptable = true;
                    // setup.OutputFormatters.Add(new XmlDataContractSerializerOutputFormatter());
                }
                )
                .AddXmlDataContractSerializerFormatters()
                .ConfigureApiBehaviorOptions(
                setup => setup.InvalidModelStateResponseFactory = context =>
                    {
                        var problemDetails = new ValidationProblemDetails(context.ModelState)
                        {
                            Type = "www.baidu.com",
                            Title = "error",
                            Status = StatusCodes.Status422UnprocessableEntity,
                            Detail = "请看详细信息",
                            Instance = context.HttpContext.Request.Path
                        };
                        problemDetails.Extensions.Add("traceId", context.HttpContext.TraceIdentifier);
                        return new UnprocessableEntityObjectResult(problemDetails)
                        {
                            ContentTypes = { "application/problem+json" }
                        };
                    }
                );