为 MassTransit SQS 调用 ReceiveEndpoint 时如何防止 NullReferenceException？

如何解决为 MassTransit SQS 调用 ReceiveEndpoint 时如何防止 NullReferenceException？

我在 .NET 核心 Web 应用程序 (Web api) 中使用 MassTransit 来使用 SQS。它可以很好地发布消息。但是在我尝试添加消费者后，我遇到了一个问题。

这是我的代码

    public static void UseMassTransit(this IServiceCollection services,MassTransitConfiguration massTransitConfiguration)
    {
        services.AddMassTransit(x =>
        {
            x.AddConsumer<CustomerChangeConsumer>();
            x.UsingAmazonSqs((context,cfg) =>
            {
                cfg.Host(massTransitConfiguration.Host,h =>
                {
                    h.AccessKey(massTransitConfiguration.AccessKey);
                    h.SecretKey(massTransitConfiguration.SecretKey);

                    cfg.ReceiveEndpoint("CustomerChangeConsumer",configurator =>
                    {
                        configurator.ConfigureConsumer<CustomerChangeConsumer>(context);
                    });

                    // scope topics as well
                    h.EnableScopedTopics();
                });
            });
        });
        services.AddMassTransitHostedService();
    }

问题在于 ReceiveEndpoint 给出了 NullReferenceException。

这很奇怪，因为 ConfigureConsumer 被执行了。但是，ReceiveEndpoint 不能完全完成而不抛出这个异常。

这是堆栈跟踪：

MassTransit.AmazonSqsTransport.Configurators.ConfigurationHostSettings.FormatHostAddress()
System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication,Boolean useDefaultConstructor)
System.Lazy`1.CreateValue()
System.Lazy`1.Value
MassTransit.AmazonSqsTransport.Configurators.ConfigurationHostSettings.HostAddress
MassTransit.AmazonSqsTransport.Configuration.AmazonSqsHostConfiguration.HostAddress
MassTransit.AmazonSqsTransport.Configuration.AmazonSqsReceiveEndpointConfiguration.FormatInputAddress()
System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication,Boolean useDefaultConstructor)
System.Lazy`1.CreateValue()
System.Lazy`1.Value
MassTransit.AmazonSqsTransport.Configuration.AmazonSqsReceiveEndpointConfiguration.InputAddress
MassTransit.Monitoring.Health.EndpointHealth.EndpointConfigured(T configurator)
MassTransit.Monitoring.Health.BusHealth.MassTransit.EndpointConfigurators.IEndpointConfigurationObserver.EndpointConfigured[T](T configurator)
MassTransit.EndpointConfigurators.EndpointConfigurationObservable.<>c__DisplayClass0_0`1.<EndpointConfigured>b__0(IEndpointConfigurationObserver observer)
GreenPipes.Util.Connectable`1.All(Func`2 callback)
MassTransit.EndpointConfigurators.EndpointConfigurationObservable.EndpointConfigured(T configurator)
MassTransit.AmazonSqsTransport.Configuration.AmazonSqsHostConfiguration.CreateReceiveEndpointConfiguration(QueueReceiveSettings settings,IAmazonSqsEndpointConfiguration endpointConfiguration,Action`1 configure)
MassTransit.AmazonSqsTransport.Configuration.AmazonSqsHostConfiguration.CreateReceiveEndpointConfiguration(String queueName,Action`1 configure)
MassTransit.AmazonSqsTransport.Configuration.AmazonSqsHostConfiguration.ReceiveEndpoint(String queueName,Action`1 configureEndpoint)
MassTransit.AmazonSqsTransport.Configurators.AmazonSqsBusFactoryConfigurator.ReceiveEndpoint(String queueName,Action`1 configureEndpoint)
Kinley.SMPD.CustomerService.API.Extensions.MassTransitExtensions.<>c__DisplayClass0_1.<UseMassTransit>b__2(IAmazonSqsHostConfigurator h) in MassTransitExtensions.cs: line: 23

怎么会？以及如何解决？

解决方法

您不应在主机配置闭包内配置接收端点。尝试将其移到 .Host() 方法之外，看看是否能解决您的问题。