System.ComponentModel.DataAnnotations attribute not recognized. Unable to use StringLength attibute to verify empty string

Question

I am looking for a way to validate data contracts in ASP.net web API. When a client hits POST request, I want to validate the request body before doing any processing. Request:

curl --location --request POST 'http://some-url/PersonService/Person' \
--header 'Content-Type: application/json' \
--header 'Content-Type: text/plain' \
--data-raw '{
  "Name": "John",
  "Age": 23
}'

Data contract:

namspace Person.DataContracts {
    [DataContract]
    class Person{

        [DataMember(IsRequired = true)]
        [StringLength(30, MinimumLength = 1)]
        private string Name {get; set;}

        [DataMember]
        private int Age {get; set;}
    }
}

Controller:

namespace Person.Controllers
{
    public sealed class PersonController : Controller, IPersonController
    {
        [HttpPost]
        [ValidatModel]
        [Route("Person")]
        public Task<Person> RegisterOrUpdateDataset([FromBody] Person person)
        {
            // Method body
        }
     }
}

ValidateModel Attribute:

namespace Person.Filters
{
    using System;
    using Microsoft.AspNetCore.Mvc.Filters;

    [AttributeUsage(AttributeTargets.Method, AllowMultiple = false)]
    public class ValidateModelAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext actionContext)
        {
            if (actionContext.ModelState.IsValid == false)
            {
                // handle validation failure
            }
        }
    }
}

I want to verify that the request body should not contain empty person name. For that, I tried using System.ComponentModel.DataAnnotations StringLength attribute but somehow this attribute is not honoured. I have also tried using MinLength(1) attribute but still facing the same issue.

Answer 1

Add [Required] to your model. It should work!