您可以创建一个ValidationBehavior类来获取错误并重新抛出异常或将错误转换到您的模型中

public class ValidationBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
    where TRequest : class, IRequest<TResponse>
{
    private readonly IEnumerable<IValidator<TRequest>> _validators;
    public ValidationBehavior(IEnumerable<IValidator<TRequest>> validators) => _validators = validators;
     public async Task<TResponse> Handle(TRequest request, RequestHandlerDelegate<TResponse> next, CancellationToken cancellationToken)
    {
        if (!_validators.Any())
        {
            return await next();
        }
        var context = new ValidationContext<TRequest>(request);
        var errorsDictionary = _validators
            .Select(x => x.Validate(context))
            .SelectMany(x => x.Errors)
            .Where(x => x != null)
            .GroupBy(
                x => x.PropertyName,
                x => x.ErrorMessage,
                (propertyName, errorMessages) => new
                {
                    Key = propertyName,
                    Values = errorMessages.Distinct().ToArray()
                })
            .ToDictionary(x => x.Key, x => x.Values);

        if (errorsDictionary.Any())
        {
            throw new CustomValidationException(errorsDictionary);
            // throw new Exception(); 
        }
        return await next();
    }
}

CustomValidationException类：

public class CustomValidationException : Exception
{
    public CustomValidationException()
        : base("Custom validation exception have occurred.")
    {
        Errors = new List<ErrorDto>();
    }

    public CustomValidationException(Dictionary<string, string[]> failures)
        : this()
    {
        foreach (var failure in failures)
        {
            foreach (var message in failure.Value)
            {
                Errors.Add(new ErrorDto(failure.Key, message));
            }
        }
    }
    public List<ErrorDto> Errors { get; }
}

ErrorDto类：

public class ErrorDto
{
    public ErrorDto(string propertyName, string message)
    {
        PropertyName = propertyName;
        Message = message;
    }

    public string Message { get; set; }

    public string PropertyName { get; set; }
}

更新：

您应该安装FluentValidation和MediatR包。