C# RulesEngine 规则引擎：从入门到看懵( 三 ) _生活百科

RuleParameter 。
var rp1 = new RuleParameter("buyer", new Buyer{Id = 666,Age = 20,Authenticated = true});var rp2 = new RuleParameter("vip", new VIP{Id = 666,IsVIP = false});

相当于表达式树：
ParameterExpression rp1 = Expression.Parameter(typeof(Buyer), "buyer");ParameterExpression rp2 = Expression.Parameter(typeof(VIP), "vip");可以参考笔者的表达式树系列文章：https://ex.whuanle.cn/

然后重新设计 JSON，增加一个 Rule：

[{	"WorkflowName": "Test",	"Rules": [{"RuleName": "CheckAuthenticated","Expression": "buyer.Authenticated == true"},{"RuleName": "CheckAge","Expression": "buyer.Age >= 18"},{"RuleName": "CheckVIP","Expression": "vip.IsVIP == true"}	]}]

然后执行此 Workflow：
List<RuleResultTree> resultList = await bre.ExecuteAllRulesAsync("Test", rp1, rp2);

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完整代码：

static async Task Main(){// 定义var rulesStr = ... ... // JSONvar workflows = JsonConvert.DeserializeObject<List<Workflow>>(rulesStr)!;var bre = new RulesEngine.RulesEngine(workflows.ToArray());var rp1 = new RuleParameter("buyer", new Buyer{Id = 666,Age = 20,Authenticated = true});var rp2 = new RuleParameter("vip", new VIP{Id = 666,IsVIP = false});List<RuleResultTree> resultList = await bre.ExecuteAllRulesAsync("Test", rp1, rp2);foreach (var item in resultList){Console.WriteLine("规则名称：{0},验证结果：{1}", item.Rule.RuleName, item.IsSuccess);}}

全局参数、本地参数全局参数在 Workflow 中可以定义全局参数，参数对 Workflow 内的所有 Rule 起效，所有 Rule 都可以使用它。
定义示例：
"WorkflowName": "Test", "GlobalParams": [{"Name": "age","Expression": "buyer.Age" }],参数的值，可以定义为常量，也可以来源于传入的参数。
修改上一个小节的示例，在 Rule CheckAge 中，使用这个全局参数。

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[{	"WorkflowName": "Test",	"GlobalParams": [{"Name": "age","Expression": "buyer.Age"	}],	"Rules": [{"RuleName": "CheckAuthenticated","Expression": "buyer.Authenticated == true"},{"RuleName": "CheckAge","Expression": "age >= 18"},{"RuleName": "CheckVIP","Expression": "vip.IsVIP == true"}	]}]

本地参数本地参数在 Rule 内定义，只对当前 Rule 起效。

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[{	"WorkflowName": "Test",	"Rules": [{"RuleName": "CheckAuthenticated","LocalParams": [{"Name": "age","Expression": "buyer.Age"}],"Expression": "buyer.Authenticated == true"},{"RuleName": "CheckAge","Expression": "age >= 18"},{"RuleName": "CheckVIP","Expression": "vip.IsVIP == true"}	]}]

在定义参数时，参数的值可以通过执行函数来获取：
"LocalParams":[{"Name":"mylocal1","Expression":"myInput.hello.ToLower()"}],LocalParams 可以使用 GlobalParams 的参数再次生成新的变量。

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"GlobalParams":[{"Name":"myglobal1""Expression":"myInput.hello"}],"Rules":[{"RuleName": "checkGlobalAndLocalEqualsHello","LocalParams":[{"Name": "mylocal1","Expression": "myglobal1.ToLower()"}]},

定义验证成功、失败行为可以为每个 Rule 定义验证成功和失败后执行一些代码。
格式示例：

"Actions": {"OnSuccess": {"Name": "OutputExpression","Context": {"Expression": "input1.TotalBilled * 0.8"}},"OnFailure": {"Name": "EvaluateRule","Context": {"WorkflowName": "inputWorkflow","ruleName": "GiveDiscount10Percent"}}}

OutputExpression 里面定义了执行代码：