实现一个对象验证库系列 -- 3) Fluent以及扩展方法实现 (请大神批评)

前情回顾：

上一篇 2) 验证器实现简单描述了下验证器的简单实现

本文将说说Fluent方式的实现，欢迎大神们指点指点

3) Fluent以及扩展方法实现

我们按照之前 Fluent 的设想以及我们解耦的方式，所以我们先实现一个创建验证器创建者的静态类：

public static class Validation{	public static IValidatorBuilder<T> NewValidatorBuilder<T>()  // 创建验证器创建者	{		return Container.Resolve<IValidatorBuilder<T>>();	}	public static ValidateContext CreateContext(object validateObject,		ValidateOption option = ValidateOption.StopOnFirstFailure, params string[] ruleSetList)  // 创建验证数据上下文参数	{		var result = Container.Resolve<ValidateContext>();		result.Option = option;		result.RuleSetList = ruleSetList;		result.ValidateObject = validateObject;		return result;	}}

我们接着实现 IValidatorBuilder

public class ValidatorBuilder<T> : IValidatorBuilder<T>{	public ObservableCollection<IValidateRuleBuilder> Builders { get; set; }	public ValidatorBuilder()	{		Builders = new ObservableCollection<IValidateRuleBuilder>();	}	public IValidator Build()	// 最终build 方法	{		var result = Container.Resolve<IValidatorSetter>();		result.SetRules(Builders.Select(i => i.Build()));		return result;	}	public IFluentRuleBuilder<T, TProperty> RuleFor<TProperty>(Expression<Func<T, TProperty>> expression)  // 验证规则创建者方法	{		ParamHelper.CheckParamNull(expression, "expression", "Can't be null");		var builder = Container.Resolve<IRuleBuilder<T, TProperty>>();		builder.SetValueGetter(expression);		Builders.Add(builder as IValidateRuleBuilder);		return builder;	}	public void RuleSet(string ruleSet, Action<IValidatorBuilder<T>> action)   // 规则分组标志设置方法	{		ParamHelper.CheckParamEmptyOrNull(ruleSet, "ruleSet", "Can't be null");		ParamHelper.CheckParamNull(action, "action", "Can't be null");		var upRuleSet = ruleSet.ToUpper();		var updateRuleSet = new NotifyCollectionChangedEventHandler<IValidateRuleBuilder>((o, e) =>		{			if (e.Action != NotifyCollectionChangedAction.Add) return;			foreach (var item in e.NewItems)			{				item.RuleSet = upRuleSet;			}		});		Builders.CollectionChanged += updateRuleSet;		action(this);		Builders.CollectionChanged -= updateRuleSet;	}	    // 规则分组标志设置方法这样实现可以简化设置的格式，让代码更清晰    // 比如    //	      var builder = Validation.NewValidatorBuilder<Student>();    //        builder.RuleSet("A", b =>    //        {    //            b.RuleFor(i => i.Name).NotNull()    //                    .Must(i=>i.Length > 10)    //                    .OverrideName("student name")    //                    .OverrideError("no name")    //              .ThenRuleFor(i => i.Age)    //                    .Must(i => i >= 0 && i <= 18)    //                    .OverrideName("student age")    //                    .OverrideError("not student");    //        });}

接着我们实现 IRuleBuilder：

public class RuleBuilder<T, TValue> : IRuleBuilder<T, TValue>{	public string RuleSet { get; set; }	public Func<object, TValue> ValueGetter { get; protected set; }	public Expression<Func<T, TValue>> ValueExpression { get; protected set; }	public string ValueName { get; set; }	public string Error { get; set; }	public IValidateRuleBuilder NextRuleBuilder { get; set; }	public Func<ValidateContext, bool> Condition { get; set; }	public Func<ValidateContext, string, string, IValidateResult> ValidateFunc { get; set; }	public void SetValueGetter(Expression<Func<T, TValue>> expression)  // 设置获取值的方法	{		ValueExpression = expression;		var stack = new Stack<MemberInfo>();		var memberExp = expression.Body as MemberExpression;		while (memberExp != null)		{			stack.Push(memberExp.Member);			memberExp = memberExp.Expression as MemberExpression;		}		var p = Expression.Parameter(typeof(object), "p");		var convert = Expression.Convert(p, typeof(T));		Expression exp = convert;		if (stack.Count > 0)		{			while (stack.Count > 0)			{				exp = Expression.MakeMemberAccess(exp, stack.Pop());			}			ValueName = exp.ToString().Replace(convert.ToString() + ".", "");  // 设置默认的属性名		}		else		{			ValueName = string.Empty;		}		ValueGetter = Expression.Lambda<Func<object, TValue>>(exp, p).Compile(); // 用表达式生成动态获取不同对象的值的方法	}	public IFluentRuleBuilder<T, TProperty> ThenRuleFor<TProperty>(Expression<Func<T, TProperty>> expression) // 创建子级规则接口方法	{		var builder = Utils.RuleFor(expression);		NextRuleBuilder = builder as IValidateRuleBuilder;		return builder;	}	public IValidateRule Build() // 规则创建方法	{		var rule = Container.Resolve<IValidateRule>();		rule.ValueName = ValueName;		rule.Error = Error;		rule.ValidateFunc = ValidateFunc;		rule.Condition = Condition;		rule.RuleSet = RuleSet;		var nextBuilder = NextRuleBuilder;		if (nextBuilder != null)			rule.NextRule = nextBuilder.Build();		return rule;	}}

貌似我们完成了大部分了，但是好像哪里不对，

回忆一下，好像这个持有如何验证逻辑方法的属性没有相关代码处理

public class ValidateRule : IValidateRule{	public Func<ValidateContext, string, string, IValidateResult> ValidateFunc { get; set; }}

好吧，我们来建立一个基类先：

public abstract class BaseChecker<T, TProperty>{	public virtual IRuleMessageBuilder<T, TProperty> SetValidate(IFluentRuleBuilder<T, TProperty> builder) // 设置验证规则逻辑方法	{		ParamHelper.CheckParamNull(builder, "builder", "Can't be null");		var build = builder as IRuleBuilder<T, TProperty>;		build.ValidateFunc = (context, name, error) =>		{			var value = build.ValueGetter(context.ValidateObject);			var result = Container.Resolve<IValidateResult>();			return Validate(result, value, name, error);		};		return build as IRuleMessageBuilder<T, TProperty>;	}	public IValidateResult GetResult()        // 获取验证结果实例对象	{		return Container.Resolve<IValidateResult>();	}	public void AddFailure(IValidateResult result, string name, object value, string error) // 添加错误信息	{		result.Failures.Add(new ValidateFailure()		{			Name = name,			Value = value,			Error = error		});	}	public abstract IValidateResult Validate(IValidateResult result, TProperty value, string name, string error); // 验证规则逻辑接口}

再接着我们实现一个Must check 类：

public class MustChecker<T, TProperty> : BaseChecker<T, TProperty>{	private Func<TProperty, bool> m_MustBeTrue;	public MustChecker(Func<TProperty, bool> func)	{		ParamHelper.CheckParamNull(func, "func", "Can't be null");		m_MustBeTrue = func;	}	public override IValidateResult Validate(IValidateResult result, TProperty value, string name, string error)	{		if (!m_MustBeTrue(value))		{			AddFailure(result, name, value, error);		}		return result;	}}

然后我们接口绑定加上：

public static class Container{	public static ILifetimeScope CurrentScope { get; set; }	public static void Init(Action<ContainerBuilder> action)	{		ParamHelper.CheckParamNull(action, "action", "Can't be null");		Clear();		var builder = new ContainerBuilder();		action(builder);		var container = builder.Build();		CurrentScope = container.BeginLifetimeScope();	}	public static void Init()	{		Init(builder =>		{			builder.RegisterType<RuleSelector>().As<IRuleSelector>().SingleInstance();			builder.RegisterGeneric(typeof(RuleBuilder<,>)).As(typeof(IRuleBuilder<,>)).InstancePerDependency();			builder.Register(c => new ValidateContext() { RuleSelector = c.Resolve<IRuleSelector>() });			builder.RegisterType<ValidateRule>().As<IValidateRule>().InstancePerDependency();			builder.RegisterType<ValidateResult>().As<IValidateResult>().InstancePerDependency();			builder.RegisterGeneric(typeof(ValidatorBuilder<>)).As(typeof(IValidatorBuilder<>)).InstancePerDependency();			builder.RegisterType<Validator>().As<IValidatorSetter>().InstancePerDependency();		});	}	public static void Clear()	{		var scope = CurrentScope;		if (scope != null)			scope.Dispose();	}	public static T Resolve<T>()	{		return CurrentScope.Resolve<T>();	}}

再然后我们添加 must 的扩展方法：

public static class Syntax{	public static IRuleMessageBuilder<T, TProperty> Must<T, TProperty>(this IFluentRuleBuilder<T, TProperty> builder, Func<TProperty, bool> func)	{		return new MustChecker<T, TProperty>(func).SetValidate(builder);	}}

我们再添加一些消息设置相关的扩展方法：

public static class Syntax{	....	public static IRuleMessageBuilder<T, TProperty> When<T, TProperty>(this IRuleMessageBuilder<T, TProperty> builder, Func<TProperty, bool> func)	{		ParamHelper.CheckParamNull(func, "func", "Can't be null");		var ruleBuilder = builder as IRuleBuilder<T, TProperty>;		ruleBuilder.Condition = (context) =>		{			var value = ruleBuilder.ValueGetter(context.ValidateObject);			return func(value);		};		return builder;	}	public static IRuleMessageBuilder<T, TProperty> OverrideName<T, TProperty>(this IRuleMessageBuilder<T, TProperty> builder, string name)	{		(builder as IValidateRuleBuilder).ValueName = name;		return builder;	}	public static IRuleMessageBuilder<T, TProperty> OverrideError<T, TProperty>(this IRuleMessageBuilder<T, TProperty> builder, string error)	{		(builder as IValidateRuleBuilder).Error = error;		return builder;	}}

大功告成，我们现在就可以这样使用了：

Container.Init();var builder = Validation.NewValidatorBuilder<Student>();builder.RuleSet("A", b =>{	b.RuleFor(i => i.Name).Must(i=>i.Length > 10)			.OverrideName("student name")			.OverrideError("no name")	  .ThenRuleFor(i => i.Age)			.Must(i => i >= 0 && i <= 18)			.OverrideName("student age")			.OverrideError("not student");});var v = builder.Build();var student = new BigStudent() { Age = 13, Name = "v" };var context = Validation.CreateContext(student);var result = v.Validate(context);Assert.IsNotNull(result);Assert.True(result.IsValid);Assert.True(result.Failures.Count == 0);

最后代码和dll可以通过如下方法获取：

nuget：https://www.nuget.org/packages/ObjectValidator/

github：https://github.com/fs7744/ObjectValidator

PS: 大神们快快给我些批评吧，冰天雪地跪求了

2楼Little Ming: 看你写出来这么多,也是听不容易的.长篇大论的,我都不知道具体要验证什么.，看到最后,知道是写的一个验证的规则. 我想问一下,大概会在什么时候使用到这些验证规则.查数据的时候,sql都有过滤, 这样验证有什么好处吗?因为之前都没有想到过要用验证器,不知道lz是怎么想到要用这个的?

1楼RainbowSky: https://github.com/JeremySkinner/FluentValidation，我想说的是，有什么好批评的，都是抄袭