asp.net web开发 ASP.NET Core Web API下事件驱动型架构的实(3)

EventStore实现好了，接下来，我们将其用在CustomerCreatedEventHandler中，以便将订阅的CustomerCreatedEvent保存下来。

事件数据的保存

保存事件数据的第一步，就是在ASP.NET Core Web API的IoC容器中，将DapperEventStore注册进去。这一步是非常简单的，只需要在Startup.cs的ConfigureServices方法中完成即可。代码如下：

public void ConfigureServices(IServiceCollection services)

{

services.AddMvc();

services.AddTransient<IEventHandler, CustomerCreatedEventHandler>();

services.AddTransient<IEventStore>(serviceProvider => new DapperEventStore(Configuration[ "mssql:connectionString" ]));

services.AddSingleton<IEventBus, PassThroughEventBus>();

}

注意我们使用的是services.AddTransient方法来注册DapperEventStore，我们希望应用程序在每次请求IEventStore实例时，都能获得一个新的DapperEventStore的实例。

接下来，打开CustomerCreatedEventHandler.cs文件，在构造函数中加入对IEventStore的依赖，然后修改HandleAsync方法，在该方法中使用IEventStore的实例来完成事件数据的保存。代码如下：

public class CustomerCreatedEventHandler : IEventHandler<CustomerCreatedEvent>

{

private readonly IEventStore eventStore;

public CustomerCreatedEventHandler(IEventStore eventStore)

{

this .eventStore = eventStore;

}

public bool CanHandle(IEvent @ event )

=> @ event .GetType().Equals( typeof (CustomerCreatedEvent));

public async Task< bool > HandleAsync(CustomerCreatedEvent @ event , CancellationToken cancellationToken = default )

{

await this .eventStore.SaveEventAsync(@ event );

return true ;

}

public Task< bool > HandleAsync(IEvent @ event , CancellationToken cancellationToken = default )

=> CanHandle(@ event ) ? HandleAsync((CustomerCreatedEvent)@ event , cancellationToken) : Task.FromResult( false );

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