Asp.Net Core6.0中MediatR的应用CQRS( 四 ) _生活百科

{ public Task Handle(OrderCreateCommand notification, CancellationToken cancellationToken) { Console.WriteLine("4444444——————————————第四个操作呢！"); return Task.CompletedTask; } } ///

/// 创建订单后处理步骤5 ///

public class OrderCreateFiveHandler : INotificationHandler { public Task Handle(OrderCreateCommand notification, CancellationToken cancellationToken) { Console.WriteLine("55555——————————————接着奏乐接着舞！"); return Task.CompletedTask; } }} 注意：这里是用mediator的publish方法的实现的，命令查询类继承INotification就要用publish方法，继承IRequest就要用Send方法，项目目录也在左侧这样别人看着也清晰点
Asp.Net Core6.0中MediatR的应用CQRS

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7、IPipelineBehavior这个接口的作用就是在我们命令处理之前或者之后插入逻辑，类似我们的中间件，我新建一个TransactionBehavior来处理保存数据库之前之后的操作，这里的代码只判断了是否为空之前写的是判断事务是否为空，代码多就随便写了意思意思。
然后新建一个DBTransactionBehavior这里对操作数据库新增演示一下
using MediatR;using Microsoft.EntityFrameworkCore;using Microsoft.EntityFrameworkCore.Metadata.Internal;namespace MediatApi.Helper{ public class TransactionBehavior<TDBContext, TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse> where TRequest : IRequest<TResponse> where TDBContext : WyyDbContext { ILogger _logger; WyyDbContext _dbContext; public TransactionBehavior(ILogger logger, WyyDbContext dbContext) { _logger = logger ?? throw new ArgumentNullException(nameof(logger)); _dbContext = dbContext ?? throw new ArgumentNullException(nameof(dbContext)); } public async Task<TResponse> Handle(TRequest request, RequestHandlerDelegate<TResponse> next, CancellationToken cancellationToken) { var response = default(TResponse); try { Console.WriteLine("执行前逻辑++++++++++++++++++++++++++++++++++"); Console.WriteLine(); if (request != null) return await next(); Console.WriteLine("逻辑不对处理++++++++++++++++++++++++++++++++"); Console.WriteLine(); var strategy = _dbContext.Database.CreateExecutionStrategy(); await strategy.ExecuteAsync(async () => { Guid transactionId; using (var transaction = await _dbContext.Database.BeginTransactionAsync()) using (_logger.BeginScope("TransactionContext:{TransactionId}", transaction.TransactionId)) { _logger.LogInformation("----- 开始事务 {TransactionId} 请求{request}", transaction.TransactionId, request); response = await next(); _logger.LogInformation("----- 提交事务 {TransactionId}}", transaction.TransactionId); await _dbContext.CommitTransactionAsync(transaction); transactionId = transaction.TransactionId; } }); return response; } catch(Exception ex) { _logger.LogError(ex, "处理事务出错{@Command}", request); throw; } } }}