c# - 从 Azure Function App 读取嵌套配置

Question

我在从 Azure Function(v6) 中的 local.settings.json 读取嵌套配置值时遇到问题，并且这些值似乎总是为 null。以下是我的代码片段:

local.settings.json:

{
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
    "FUNCTIONS_WORKER_RUNTIME": "dotnet",
    "EndpointDetails": {
      "GetAllTaskDetails": {
        "Url": "https://localhost:7000/api/Task/GetAllTaskDetails",
        "Method": "GET",
        "NotificationRecipients": "<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="d2a7a1b7a0e392b6bdbfb3bbbcfcb1bdbf" rel="noreferrer noopener nofollow">[email protected]</a>"
      },
      "GetTaskDetails": {
        "Url": "https://localhost:7000/api/Task/GetTaskDetails",
        "Method": "GET",
        "NotificationRecipients": "<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="83f6f0e6f1b1c3e7eceee2eaedade0ecee" rel="noreferrer noopener nofollow">[email protected]</a>"
      }
    }
  }
}

Startup.cs:

using Microsoft.Azure.Functions.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection;

[assembly: FunctionsStartup(typeof(HealthChecker.Startup))]
namespace HealthChecker
{
    public class Startup : FunctionsStartup
    {
        public override void Configure(IFunctionsHostBuilder builder)
        {
            // Getting the IConfiguration instance
            var configuration = builder.GetContext().Configuration;

            // Registering health checks
            builder.Services.AddHealthChecks();

            // Calling the method that defines health checks
            HealthCheckDefinitions.ConfigureHealthChecks(builder.Services.AddHealthChecks(), configuration);
        }
    }
}

HealthCheckDefinitions.cs:

public static class HealthCheckDefinitions
{
 private static Dictionary<string, List<string>> endpointDetails = new Dictionary<string, List<string>>();

 public static void ConfigureHealthChecks(IHealthChecksBuilder builder, IConfiguration configuration){
     private static IConfigurationSection endpointDetailsListConfig;
     private static string getAllTaskDetails;
     private static string getTaskDetails;
     List<string> endpoints = new List<string>();

     InitializeConfigValues(configuration);

     endpoints.AddRange(new List<string>
            {
                 getAllTaskDetails,
                 getTaskDetails
            });

     foreach (var endpoint in endpoints)
            {
                var endpointDetailsConfig 
                  = endpointDetailsListConfig.GetSection(endpoint);
                GetEndpointDetails(endpointDetailsConfig, endpoint);
               
                foreach (var endpointDetail in endpointDetails)
                {
                  builder.AddCheck(endpointDetail.Key, () =>
                  {
                    // lines of code
                    // .....
                  });
                }
            }
   }
 
 private static void InitializeConfigValues(IConfiguration configuration)
    {
        endpointDetailsListConfig = configuration.GetSection("EndpointDetails");
        getAllTaskDetails = endpointDetailsListConfig.GetSection("GetAllTaskDetails").Key;
        getTaskDetails = endpointDetailsListConfig.GetSection("GetTaskDetails").Key;
    }

   private static void GetEndpointDetails(IConfigurationSection endpointDetailsConfig, string endpoint)
    {
        if (!string.IsNullOrEmpty(endpointDetailsConfig["Url"]) && !string.IsNullOrEmpty(endpointDetailsConfig["Method"])
            && !string.IsNullOrEmpty(endpointDetailsConfig["NotificationRecipients"]))
            {
                endpointDetails.Add(endpoint, new List<string>
                {
                    endpointDetailsConfig["Url"],
                    endpointDetailsConfig["Method"],
                    endpointDetailsConfig["NotificationRecipients"]
                });
            }
    }
}

以下值始终为空。我哪里出错了？

                endpointDetailsConfig["Url"],
                endpointDetailsConfig["Method"],
                endpointDetailsConfig["NotificationRecipients"]

Answer 1

在您的 local.settings.json 文件中，"GetAllTask​​Details" 和 "GetTaskDetails" 存在于此处:

{
  "Values": {
    "EndpointDetails": {
      "GetAllTaskDetails": {
        ...
      },
      "GetTaskDetails": {
        ...
      }
    }
  }
}

即在这些路径:

"Values:EndpointDetails:GetAllTaskDetails"
"Values:EndpointDetails:GetTaskDetails"

通过设置

endpointDetailsListConfig = configuration.GetSection("EndpointDetails");

，您尝试定位不在配置根级别的部分。因此，GetSection() 的返回值不应该是实际的配置节。

根据 .GetSection() documentation :

This method will never return null. If no matching sub-section is found with the specified key, an empty IConfigurationSection will be returned.

旁注:
要验证某个部分(或值)是否存在，请调用 .Exists() .GetSection() 的返回值。

<小时/>

如果您更愿意定位“Values:EndpointDetails”，您应该能够从那里正确遍历树:

endpointDetailsListConfig = configuration.GetSection("Values:EndpointDetails");