azure - 使用 Azure 搜索 .NET 检查索引是否存在时出现 NullReferenceException？

Question

当尝试使用 .NET SDK(3.0.4 和 4.0.0-preview)查看不存在的索引是否存在时，ExistsAsync(以及 Exists 和 ExistsWithHttpMessagesAsync) 引发以下异常。

System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.Azure.Search.IndexesOperations.<GetWithHttpMessagesAsync>d__12.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Search.ExistsHelper.<ExistsFromGetResponse>d__0`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.Azure.Search.IndexesOperationsExtensions.<ExistsAsync>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at InphizCore.MiddleLayer.Services.AzureSearch.Services.AzureSearchWriter`1.<AssertIndexExists>d__8.MoveNext() in C:\xxx\AzureSearchWriter.cs:line 109

使用 postman 的 http Rest 工作正常，并返回一条消息，指出索引不存在。

 public async Task AssertIndexExists()
        {
            try
            {
                if (await searchServiceClient.Indexes.ExistsAsync(options.Value.IndexName) == false)
                {
                    searchServiceClient.Indexes.Create(new Index(options.Value.IndexName, FieldBuilder.BuildForType<SearchableItemModel>(), corsOptions: new CorsOptions(new List<string> { "*" })));
                }
            }
            catch (Exception e)
            {
                logger.LogError($"Azure Search Index '{options.Value.IndexName}' could not be created. ({e.Message})");
                throw e;
            }
        }

如何以有意义的方式解决此问题？

更新:

这是客户端在单元测试中运行时的样子:

这就是 AspNetCore MVC 的样子:

搜索客户端似乎无法创建 FirstMessageHandler、HttpClient 和 HttpClientHandler 的实例。为什么不抛出？

Answer 1

嗯，这很奇怪，但可能是 SearchServiceClient 的一些内部工作原理。

这(编辑:不起作用):

如果我添加一个 HttpClientHandler 并将其传递给另一个构造函数并将生命周期设置为 Singleton 或 Transient ，它就可以工作。我之前有Scoped。

 services.AddTransient<SearchServiceClient>(x =>
 {
     var httpClientHandler = new HttpClientHandler();

     var options = x.GetRequiredService<IOptions<AzureSearchOptions>>();
     var client = new SearchServiceClient(options.Value.SearchServiceName, new SearchCredentials(options.Value.AdminApiKey), httpClientHandler);
     return client;
 });

更新:这有效:

上述解决方案中的行为是不可预测的，我最终在调用类中使用了此方法。

当我每次需要客户端时创建一个新实例时，它似乎根本没有给出任何错误:

  protected SearchServiceClient GetAzureSearchServiceClient()
        {
            return new SearchServiceClient(options.Value.SearchServiceName, new SearchCredentials(options.Value.AdminApiKey));
        }