本例使用的规则引擎包是RulesEngine,关于RulesEngine的介绍,请自行补充,这里只是一个极简单使用场景。
例子大体就是用户有一些优惠券,系统会根据用户订单情况,筛选可以使用的优惠券供用户选择,用户选择后会计算出优惠后金额。
代码相对简单,就不一一介绍了,奉上service中的代码:
using Microsoft.Extensions.Logging; using RulesEngine.Extensions; using RulesEngine.Models; using System; using System.Collections.Generic; using System.Linq; using System.Runtime.CompilerServices; using System.Text; using System.Threading.Tasks; namespace RulesEngineSample.Services { public class CouponService : ICouponService { private readonly ILogger<CouponService> _logger; private readonly List<Coupon> _userCoupons; private readonly Order _order; private readonly User _user; public CouponService(ILogger<CouponService> logger) { _logger = logger; //假装用户用的优惠券 _userCoupons = new List<Coupon>() { new Coupon { ID = 1, Code="YH01", Name = "满500减20", BeginTime = DateTime.Parse("2021-01-01"), EndTime = DateTime.Parse("2021-06-01"), Expression = "input1.Details.Sum(s => s.Price * Convert.ToDecimal(s.Quantity))>= 500", Symbol="-", Number=20 }, new Coupon { ID = 2, Code="YH02", Name = "新人5元券", BeginTime = DateTime.Parse("2021-01-01"), EndTime = DateTime.Parse("2021-06-01"), Expression = "input1.Details.Count>0", Symbol="-", Number=5 }, new Coupon { ID = 3, Code="YH03", Name = "商品C五折", BeginTime = DateTime.Parse("2021-01-01"), EndTime = DateTime.Parse("2021-06-01"), Expression = "input1.Details.Where(s=>s.GoodsID==\"SP0000003\").Count()>0", Symbol="*", Number=0.5f, GoodsID="SP0000003" }, }; //假装当前用户的订单 _order = new Order { OrderNo = "NO00000001", OrderTime = DateTime.Now, Details = new List<Detail> { new Detail{ GoodsID="SP0000001", Name="商品A", Price=12.5m, Quantity=3}, new Detail{ GoodsID="SP0000002", Name="商品B", Price=100m, Quantity=4}, new Detail{ GoodsID="SP0000003", Name="商品C", Price=22.3m, Quantity=5}, } }; _user = new User { ID = 1, UserName = "zhangsan" }; } /// <summary> /// 适配优惠券 /// </summary> /// <returns></returns> public async Task<string> SelectCouponAsync() { var workRules = new RulesEngine.Models.WorkflowRules(); workRules.WorkflowName = "优惠券"; var rules = new List<Rule>(); foreach (var coupon in _userCoupons.Where(s => s.BeginTime < DateTime.Now && s.EndTime > DateTime.Now)) { var rule = new Rule { RuleName = coupon.Name, SuccessEvent = coupon.Code, ErrorMessage = "规则应用失败", ErrorType = ErrorType.Error, RuleExpressionType = RuleExpressionType.LambdaExpression, Expression = coupon.Expression }; rules.Add(rule); } workRules.Rules = rules; var rulesEngine = new RulesEngine.RulesEngine(new WorkflowRules[] { workRules }, _logger, new ReSettings()); var ruleResults = await rulesEngine.ExecuteAllRulesAsync("优惠券", _order, _user); // var valueCoupons = new List<string>(); //处理结果 var discountCoupons = new StringBuilder(); foreach (var ruleResult in ruleResults) { if (ruleResult.IsSuccess) { discountCoupons.AppendLine($"可以使用的优惠券 “{_userCoupons.SingleOrDefault(s => s.Code == ruleResult.Rule.SuccessEvent)?.Name}”, Code是:{ruleResult.Rule.SuccessEvent}"); //valueCoupons.Add(ruleResult.Rule.SuccessEvent); } } //resultList.OnSuccess((eventName) => //{ // discountOffered += $"可以使用的优惠券“{userCoupons.SingleOrDefault(s => s.Code == eventName)?.Name}”,Code是:{eventName} "; //}); ruleResults.OnFail(() => { discountCoupons.AppendLine("您没有适合的优惠券!"); }); return discountCoupons.ToString(); } /// <summary> /// 计算订单支付总额 /// </summary> /// <param name="code"></param> /// <returns></returns> public string GetOrderAmount(string code) { var selectCoupon = _userCoupons.SingleOrDefault(s => s.Code == code); var orderAmount = 0m; switch (selectCoupon.Symbol) { case "-": orderAmount = _order.Details.Sum(s => s.Price * Convert.ToDecimal(s.Quantity)) - Convert.ToDecimal(selectCoupon.Number); break; case "*": if (!string.IsNullOrWhiteSpace(selectCoupon.GoodsID)) { orderAmount = _order.Details.Sum(s => s.Price * Convert.ToDecimal(s.Quantity)); var detail = _order.Details.SingleOrDefault(s => s.GoodsID == selectCoupon.GoodsID); if (detail != null) { orderAmount -= detail.Price * Convert.ToDecimal(detail.Quantity) * Convert.ToDecimal(1 - selectCoupon.Number); } } else { orderAmount = _order.Details.Sum(s => s.Price * Convert.ToDecimal(s.Quantity)) * Convert.ToDecimal(selectCoupon.Number); } break; } return $"订单总金额:{_order.Details.Sum(s => s.Price * Convert.ToDecimal(s.Quantity)) },优惠后请支付:{orderAmount}"; } } public class Coupon { public int ID { get; set; } public string Code { get; set; } public string Name { get; set; } public DateTime BeginTime { get; set; } public DateTime EndTime { get; set; } public string Expression { get; set; } public string Symbol { get; set; } public float Number { get; set; } public string GoodsID { get; set; } } public class User { public int ID { get; set; } public string UserName { get; set; } } public class Order { public string OrderNo { get; set; } public DateTime OrderTime { get; set; } public List<Detail> Details { get; set; } } public class Detail { public string GoodsID { get; set; } public float Quantity { get; set; } public decimal Price { get; set; } public string Name { get; set; } } }
api /selectcoupon是查询可使用的优惠券
/getamount 按优惠券code,计算本次订单的应付金额:
优惠券YH01
优惠券YH02
优惠券YH03
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