Command & Query Domain - Data Validation - Custom Validator

CQD_DataValidation_CustomValidator.cs

public class CreateUserNameValidator : IValidator<CreateUserCommand>
{
    public CreateUserNameValidator(/* dependencies */) { }

    public async ValueTask<Result<bool>> ValidateAsync(CreateUserCommand command, CancellationToken cancellation)
    {
        if (await IsValidName(command.Name)) 
            return true;

        return new ValidationError(message: "Name is not valid.");
    }
    
    public Task<bool> IsValidName(string name) => // check if name is valid somehow
}