generic method validating data using FluentValidation

Question

I am using FluentValidator in a C# project. I would like to make a generic method that can validate data from 2 possible types:

public class MyClassAValidator : AbstractValidator<MyClassA> {...}
public class MyClassBValidator : AbstractValidator<MyClassB> {...}

public void MyMt<T>(T param)
{
  AbstractValidator<T> validator = null;
  if(param is MyClassA)
  {
   var validator = new MyClassAValidator(); // Generatescompiler error
  }
  else if (cCOSLDto is CCOSLLoyerDto)
  {
    validator = new MyClassBValidator(); // Generatescompiler error
  }
  ValidationResult result = validator.Validate(param);
 }

Compiler cannot convert MyClassAValidator() or MyClassBValidator() to AbstractValidator

How can I handle this? I suspect (just a suspicion though) that it would work if I set a base class to MyClassA and MyClassB. But I would like to avoid this if possible as MyClassA and MyClassB are actually DTO classes so I would prefer them to stay without inheritence relationship.

Answer 1

Actually, if you need to validate two different types of objects in one method, you dont have to mess with inheritance from a generic class.

There is an easy way to do this. Any Validate method returns ValidationResult, so you can use something like this:

using FluentValidation;
using FluentValidation.Results;
using System;

namespace FluentValidatorTranslation
{
    class Program
    {
        static void Main(string[] args)
        {
            
        }

        public ValidationResult MyMt<T>(T param)
        {
            ValidationResult result;
            if(param is MyClassA myClassA)
            {
                var validator = new MyClassAValidator();
                result = validator.Validate(myClassA);
            }
            else if (param is MyClassB myClassB)
            {
                var validator = new MyClassBValidator();
                result = validator.Validate(myClassB);
            }
            else
            {
                throw new ArgumentException("Type not supported");
            }

            return result;
        }

    }

    public class MyClassA { }

    public class MyClassB { }

    public class MyClassAValidator : AbstractValidator<MyClassA>
    {

    }

    public class MyClassBValidator : AbstractValidator<MyClassB>
    {

    }

}