handling validation exception in asp.net core web api

Question

User1838940990 posted

Hi All,

This about asp.net core web api 3.1

I am trying to handle   when the Validation of model field happens
Below mode the maximum range for SumInsured 200000 , if I put 300000 , then it throws a validation error like below 

{
  "type": "https://tools.ietf.org/html/rfc7231#section-6.5.1",
  "title": "One or more validation errors occurred.",
  "status": 400,
  "traceId": "|90e52394-484e4c602b1e5fec.",
  "errors": {
    "SumInsured": [
      "should be greater than 100000 and less than 200000"
    ]
  }
}

But I am not able to catch here validation error in ActionFilters, UseExceptionHandler extension or  custom  ExceptionFilter

below is the Action filter implementation 

Is there any filters i can access this validation errors before the  controller send the response back 

public class UserInfo
    {
       [Required]
       [Range(100000,200000,ErrorMessage ="should be greater than {1} and less than {2}")]
        public decimal SumInsured { get; set; }

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

       [Required]
        [Range(0,80,ErrorMessage ="Age should be a number  than {1} and {2}")]
        public int Age { get; set; }

       [Required]
        public DateTime? DateOfBirth { get; set; }

    }

public class ValidationFilterAttribute : IActionFilter
    {
        public void OnActionExecuted(ActionExecutedContext context)
        {
            if (!context.ModelState.IsValid)
            {
                context.Result = new BadRequestObjectResult(context.ModelState);
            }
        }

        public void OnActionExecuting(ActionExecutingContext context)
        {
            if (!context.ModelState.IsValid)
            {
                context.Result = new BadRequestObjectResult(context.ModelState);
            }
        }

       
    }





inject dependencies instartup

    services.AddControllers(options => {
                options.Filters.Add(new ApiExceptionFilter());
                options.Filters.Add(new ValidationFilterAttribute());
            });

Answer 1

User2084015983 posted

Hello,

If you are looking to catch or retrieve the validation exception thrown, you will need to iterate through the InnerException property of the ValidationException Class.

You can refer to https://docs.microsoft.com/en-us/dotnet/api/system.componentmodel.dataannotations.validationexception?view=netcore-3.1#remarks which describes this in details.