.NetCore3 WebApi使用模型验证参数合法性

在接口开发过程中免不了要去验证参数的合法性，模型验证就是帮助我们去验证参数的合法性。我们可以在需要验证的model属性上加上Data Annotations特性后就会自动帮我们在action前去验证输入数据的合法性。

1、定义一个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验证

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

.NetCore WebApi对于参数验证默认返回样式。

{
  "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、如果想统一验证，而不是到处都是ModelState.IsValid

(1)定义Attribute继承ActionFilterAttribute，重写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类ConfigureServices

            services.AddControllers(options =>
            {
                // 添加自定义验证方式
                options.Filters.Add<ValidateModelAttribute>();
            });

            services.Configure<ApiBehaviorOptions>(options =>
            {
                // 关闭默认的验证方式
                options.SuppressModelStateInvalidFilter = true;
            });

 

这样就可以全局验证参数，而不是在Controller的Action中到处都是ModelState

验证效果

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