参考:

• https://code-maze.com/action-filters-aspnetcore/
• https://github.com/aspnet/AspNetCore.Docs/issues/12157
• https://docs.microsoft.com/en-us/aspnet/core/web-api/?view=aspnetcore-3.0#automatic-http-400-responses

1. 关闭默认模型验证过滤器
   [ApiController] 默认自带有400模型验证，且优先级比较高，如果需要自定义模型验证，则需要先关闭默认的模型验证
   在StartUp.cs 中的MVC服务配置修改

   #region MVC
   services.AddMvc(o =>
   {
   }).SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
   .ConfigureApiBehaviorOptions(o =>
   {
       o.SuppressModelStateInvalidFilter = true;
   });
    #endregion

2. 首先定义统一输出的格式为

   {
       code:
       errors:[
           filed:
           message:
       ]
   }

3. 添加自定义模型验证DTO

    public class ErrorResultDTO
       {
           /// <summary>
           /// 参数领域
           /// </summary>
           public string Field { get; set; }
   
           /// <summary>
           /// 错误信息
           /// </summary>
           public string Message { get; set; }   
       }

4. 添加过滤器
   过滤器继承自:ActionFilterAttribute, IActionFilter

   public class ModelActionFiter :ActionFilterAttribute, IActionFilter
       {
           public ModelActionFiter()
           {
           }
           public override void OnActionExecuted(ActionExecutedContext context)
           {
   
           }
   
          public override void OnActionExecuting(ActionExecutingContext context)
           {
               if (!context.ModelState.IsValid)
               {     
                   List<ErrorResultDTO> errorResults = new List<ErrorResultDTO>();
                   foreach (var item in context.ModelState)
                   {
                       var result = new ErrorResultDTO
                       {
                           Field = item.Key,
                           Msg = "",
                       };
                       foreach (var error in item.Value.Errors)
                       {
                           if (!string.IsNullOrEmpty(result.Msg))
                           {
                               result.Msg += '|';
                           }
                           result.Msg += error.ErrorMessage;
                       }
                       errorResults.Add(result);
                   }
                   context.Result = new BadRequestObjectResult(new
                   {
                       Code = StatusCodes.Status400BadRequest,
                      Errors = errorResults
                   });  
               }
           }
       }

5. 将写的过滤器注册到全局

     services.AddMvc(o =>
           {
               o.Filters.Add(new ModelActionFiter());
      })

6. 结果测试
   

7. 扩展
   • 利用拦截器来测试action 的运行时间，记录日志，并设置时间限制，超过某个时间段自动发送邮件通知维护人员

DOTNET CORE WEB API 统一模型验证拦截器