.NetCore3 WebApi使用模型驗證參數合法性

在接口開發過程中免不了要去驗證參數的合法性，模型驗證就是幫助我們去驗證參數的合法性。我們可以在需要驗證的model屬性上加上Data Annotations特性后就會自動幫我們在action前去驗證輸入數據的合法性。

1、定義一個class

    public class TokenRequest
    {
        [Required]
        [StringLength(6)]
        public string Username { get; set; }

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

2、在Controller接口中，使用ModelState.IsValid驗證

      if (!ModelState.IsValid)
      {
            return BadRequest();
      }

.NetCore WebApi對於參數驗證默認返回樣式。

{
  "type": "https://tools.ietf.org/html/rfc7231#section-6.5.1", "title": "One or more validation errors occurred.", "status": 400, "traceId": "|2cf913f6-46e1cc8505a94470.", "errors": { "Password": ["The Password field is required."], "Username": ["The Username field is required."] } }

3、如果想統一驗證，而不是到處都是ModelState.IsValid

(1)定義Attribute繼承ActionFilterAttribute，重寫OnActionExecuting方法

    public class ValidateModelAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext context)
        {
            var modelState = context.ModelState;
            if (!modelState.IsValid)
            {
                var validationErrors = modelState.Keys
                    .SelectMany(key => modelState[key].Errors.Select(x => new ValidationError(key, x.ErrorMessage)));
                context.Result = new ObjectResult(validationErrors);
            }
        }
    }

    public class ValidationError
    {
        public string Field { get; set; }

        public string Message { get; set; }

        public ValidationError(string field, string message)
        {
            Field = field;
            Message = message;
        }
    }

(2)Starup類ConfigureServices

            services.AddControllers(options =>
            {
                // 添加自定義驗證方式
                options.Filters.Add<ValidateModelAttribute>();
            });

            services.Configure<ApiBehaviorOptions>(options =>
            {
                // 關閉默認的驗證方式
                options.SuppressModelStateInvalidFilter = true;
            });

 

這樣就可以全局驗證參數，而不是在Controller的Action中到處都是ModelState

驗證效果

[{
  "field": "Password",
  "message": "The Password field is required."
}, {
  "field": "Username",
  "message": "The field Username must be a string with a maximum length of 6."
}]