Upgrade Solution to use FluentValidation Ver 10 Exception Issue - fluentvalidation

Question

Please I need your help to solve FluentValidation issue. I have an old desktop application which I wrote a few years ago. I used FluentValidation Ver 4 and Now I'm trying to upgrade this application to use .Net framework 4.8 and FluentValidation Ver 10, but unfortunately, I couldn't continue because of an exception that I still cannot fix.
I have this customer class:
class Customer : MyClassBase
{
string _CustomerName = string.Empty;
public string CustomerName
{
get { return _CustomerName; }
set
{
if (_CustomerName == value)
return;
_CustomerName = value;
}
}
class CustomerValidator : AbstractValidator<Customer>
{
public CustomerValidator()
{
RuleFor(obj => obj.CustomerName).NotEmpty().WithMessage("{PropertyName} is Empty");
}
}
protected override IValidator GetValidator()
{
return new CustomerValidator();
}
}
This is my base class:
class MyClassBase
{
public MyClassBase()
{
_Validator = GetValidator();
Validate();
}
protected IValidator _Validator = null;
protected IEnumerable<ValidationFailure> _ValidationErrors = null;
protected virtual IValidator GetValidator()
{
return null;
}
public IEnumerable<ValidationFailure> ValidationErrors
{
get { return _ValidationErrors; }
set { }
}
public void Validate()
{
if (_Validator != null)
{
var context = new ValidationContext<Object>(_Validator);
var results = _Validator.Validate(context); **// <======= Exception is here in this line**
_ValidationErrors = results.Errors;
}
}
public virtual bool IsValid
{
get
{
if (_ValidationErrors != null && _ValidationErrors.Count() > 0)
return false;
else
return true;
}
}
}
When I run the application test I get the below exception:
System.InvalidOperationException HResult=0x80131509 Message=Cannot
validate instances of type 'CustomerValidator'. This validator can
only validate instances of type 'Customer'. Source=FluentValidation
StackTrace: at
FluentValidation.ValidationContext1.GetFromNonGenericContext(IValidationContext context) in C:\Projects\FluentValidation\src\FluentValidation\IValidationContext.cs:line 211 at FluentValidation.AbstractValidator1.FluentValidation.IValidator.Validate(IValidationContext
context)
Please, what is the issue here and How can I fix it?
Thank you

Answer 1

Your overall implementation isn't what I'd consider normal usage however the problem is that you're asking FV to validate the validator instance, rather than the customer instance:
var context = new ValidationContext<Object>(_Validator);
var results = _Validator.Validate(context);
It should start working if you change it to:
var context = new ValidationContext<object>(this);
var results = _Validator.Validate(context);
You're stuck with using the object argument for the validation context unless you introduce a generic argument to the base class, or create it using reflection.