EF architecture--actual usage of FluentValidation

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In MVC, EF, and LINQ environments, we often use DataModel (DO) and ViewModel (VO). We may use characteristics to verify their properties. Of course, this is very intuitive. Even Microsoft's DEMO is like this. It usually looks like this code

        /// <summary>/// 机构ＩＤ/// </summary>[DisplayName("机构ID")]public int AgentId { get; set; }/// <summary>/// 机构名称/// </summary>[DisplayName("机构名称")]
        [MaxLength(128)]public string AgentName { get; set; }/// <summary>/// 机构负责人/// </summary>[DisplayName("机构负责人")]
        [MaxLength(128)]public string AgentUser { get; set; }

. This design method will bring many problems to our future maintenance. The specific uncle summarizes Let’s look at:

1. Mixed with data entities, without using extensions, the features you add may be lost when updating the entity

2. If there are multiple VOs , then you need to add it to the specific VO, because the semantics of DO may not be clear

3. It is not convenient for migration, and it is too highly coupled with ModelState

4. From an object-oriented perspective, its responsibilities are too single and cause too many variables

To sum up, FluentValidation was born!

Go to nuget to install it: install-package FluentValidation

You can add multiple inspection classes to one of your entity classes, which is equivalent to having multiple inspection classes. Decorating an entity class, I think it’s pretty good!

   public class CreateUserEventValidator : AbstractValidator<CreateUserEvent>{public CreateUserEventValidator()
        {
            RuleFor(command => command.UserName).NotEmpty().Length(5, 20).WithMessage("用户名升序为5－20字符！");
            RuleFor(command => command.Email).NotEmpty().EmailAddress().WithMessage("不是有效的Email！");
            RuleFor(command => command.BirthDay).NotEmpty().Must(i => i < DateTime.Now).WithMessage("你的年紀太小了！");
        }
    }

When using it, you can get the information you need through IsValid, Errors and other attributes. Of course, you can also use it on command events and domain events, such as making a Verification decorator, which handlers need to be verified, just use this decorator to decorate it, it is very elegant!

   
   BusManager.Instance.Subscribe( ValidatorDecorator<CreateUserEvent>(
 UserEventHandler(),

   BusManager.Instance.Subscribe( LoggerDecorator<CreateUserEvent>( CreateUserEvent { UserName =  });

The decorator requires you to transfer an object to be decorated and a decorator, that’s it.

    /// <summary>/// 验证装饰器/// </summary>/// <typeparam name="TEvent"></typeparam>    [Serializable]public class ValidatorDecorator<TEvent>   : IBusHandler<TEvent>where TEvent : IBusData
    {/// <summary>/// 要被装饰的处理程序/// </summary>private readonly IBusHandler<TEvent> _inner;/// <summary>/// 校验装饰器集合/// </summary>private readonly IValidator<TEvent>[] _validators;/// <summary>/// 初始化/// </summary>/// <param name="inner">要被装饰的处理程序</param>/// <param name="validators">装饰器</param>public ValidatorDecorator(IBusHandler<TEvent> inner, params IValidator<TEvent>[] validators)
        {
            _inner = inner;
            _validators = validators;
        }public void Handle(TEvent evt)
        {var failures = _validators
                           .Select(v => v.Validate(evt))
                           .SelectMany(result => result.Errors)
                           .Where(error => error != null)
                           .ToList();if (failures.Any())
            {throw new ValidationException("实体校验失败", failures);
            }

            _inner.Handle(evt);
        }
    }

The learning and understanding of a kind of knowledge requires some theoretical foundation. You can read more books such as Design Module, Introduction to Algorithms, and .netCLR!

Thank you for reading!

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