我正在尝试学习如何使用ConfigurationSection类.我曾经使用IConfigurationSectionHandler,但发布它已被贬值.所以成为一个好小伙子,我正在尝试“正确”的方式.我的问题是它总是返回null.

我有一个控制台应用程序和一个DLL.

class Program
{
    static void Main(string[] args)
    {           
        StandardConfigSectionHandler section = StandardConfigSectionHandler.GetConfiguration();

        string value = section.Value;
    }
}

应用配置：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>

  <configSections>
    <sectionGroup name="ConfigSectionGroup">
      <section name="ConfigSection" type="Controller.StandardConfigSectionHandler,Controller" />
    </sectionGroup>
  </configSections>

  <ConfigSectionGroup>
    <ConfigSection>
      <test value="1" />
    </ConfigSection>
  </ConfigSectionGroup>

</configuration>

DLL中的section handler：

namespace Controller
{    
    public class StandardConfigSectionHandler : ConfigurationSection
    {
    private const string ConfigPath = "ConfigSectionGroup/ConfigSection/";

    public static StandardConfigSectionHandler GetConfiguration()
    {
        object section = ConfigurationManager.GetSection(ConfigPath);
        return section as StandardWcfConfigSectionHandler;
    }

    [ConfigurationProperty("value")]
    public string Value
    {
        get { return (string)this["value"]; }
        set { this["value"] = value; }
    }
  }
}

有什么值得我尝试的“ConfigPath”它将返回null,或者抛出一个错误,说“test”是一个无法识别的元素.我试过的价值：

> ConfigSectionGroup
> ConfigSectionGroup /
> ConfigSectionGroup / ConfigSection
> ConfigSectionGroup / ConfigSection /
> ConfigSectionGroup / ConfigSection / test
> ConfigSectionGroup / ConfigSection / test /

你的代码有几个错误.

>你总是在你的GetConfiguration方法中返回null,但是我将假设这只是在问题中,而不是在你的实际代码中.
>更重要的是,ConfigPath值的格式不正确.您有一个尾部斜杠ConfigSectionGroup / ConfigSection /,删除最后一个斜杠,它将能够找到该部分.
>最重要的是,您声明部分的配置系统将会将您的“值”存储在ConfigSection元素的属性中.喜欢这个

<ConfigSectionGroup>
  <ConfigSection value="foo" />
</ConfigSectionGroup>

所以,把它放在一起：

public class StandardConfigSectionHandler : ConfigurationSection
{
    private const string ConfigPath = "ConfigSectionGroup/ConfigSection";

    public static StandardConfigSectionHandler GetConfiguration()
    {
        return (StandardConfigSectionHandler)ConfigurationManager.GetSection(ConfigPath);
    }

    [ConfigurationProperty("value")]
    public string Value
    {
        get { return (string)this["value"]; }
        set { this["value"] = value; }
    }
}

要了解有关如何配置配置部分的更多信息,请参阅这个出色的MSDN文档：How to: Create Custom Configuration Sections Using ConfigurationSection.它还包含有关如何将配置值存储在(像您的测试元素)的子元素中的信息.

在我的集成测试中,我使用的是我正在测试的Web API项目中构建的相同的SimpleInjector.Container.

但是组合根类中的这一行：

container.RegisterWebApiControllers(GlobalConfiguration.Configuration);

导致异常：

System.TypeInitializationException : The type initializer for 'MyProject.Api.Test.Integration.HttpClientFactory' threw an exception.
---- system.invalidOperationException : This method cannot be called during the application's pre-start initialization phase.
Result StackTrace:  
at MyProject.Api.Test.Integration.HttpClientFactory.Create()
   at MyProject.Api.Test.Integration.Controllers.ProductControllerIntegrationTest.<GetProductBarcode_Should_Return_Status_BadRequest_When_Barcode_Is_Empty>d__0.MoveNext() in d:\Projects\My\MyProject.Api.Test.Integration\Controllers\ProductControllerIntegrationTest.cs:line 26
----- Inner Stack Trace -----
   at System.Web.Compilation.BuildManager.EnsuretopLevelFilesCompiled()
   at System.Web.Compilation.BuildManager.GetReferencedAssemblies()
   at System.Web.Http.WebHost.WebHostAssembliesResolver.System.Web.Http.dispatcher.IAssembliesResolver.GetAssemblies()
   at System.Web.Http.dispatcher.DefaultHttpControllerTypeResolver.GetControllerTypes(IAssembliesResolver assembliesResolver)
   at System.Web.Http.WebHost.WebHostHttpControllerTypeResolver.GetControllerTypes(IAssembliesResolver assembliesResolver)
   at SimpleInjector.SimpleInjectorWebApiExtensions.GetControllerTypesFromConfiguration(HttpConfiguration configuration)
   at SimpleInjector.SimpleInjectorWebApiExtensions.RegisterWebApiControllers(Container container,HttpConfiguration configuration)
   at MyProject.Api.ContainerConfig.RegisterTypes(Container container) in d:\Projects\My\MyProject.Api\App_Start\ContainerConfig.cs:line 128
   at MyProject.Api.ContainerConfig.CreateWebApiContainer() in d:\Projects\My\MyProject.Api\App_Start\ContainerConfig.cs:line 63
   at MyProject.Api.Test.Integration.HttpClientFactory..cctor() in d:\Projects\My\MyProject.Api.Test.Integration\HttpClientFactory.cs:line 17

评论后,一切正常,网络应用程序本身和测试.

所以问题是：

>例外的原因是什么？
>(这种方法真的需要吗？)

这是HttpClientFactory的代码(一个辅助类,用于创建具有适当头的HttpClient,例如api密钥或授权)：

internal static class HttpClientFactory
{
    private static readonly Container _container = ContainerConfig.CreateWebApiContainer();

    public static HttpClient Create()
    {
        var client = new HttpClient { BaseAddress = GetUrl() };
        //...
        return client;
    }
}

如果我们仔细观察堆栈跟踪,我们可以准确地看到这里发生了什么. RegisterWebApiControllers扩展方法在从HttpConfiguration获取的IHttpControllerTypeResolver实例上调用GetControllerTypes方法,并传递也从配置中检索的IAssembliesResolver.调用GetControllerTypes方法(WebHostHttpControllerTypeResolver)调用DefaultHttpControllerTypeResolver的GetControllerTypes,最终将调用System.Web.Compilation.BuildManager类的GetReferencedAssemblies.

但是,System.Web.Compilation.BuildManager不能在ASP.NET管道的早期调用,也不能在ASP.NET的上下文之外调用.由于您正在进行测试,BuildManage将抛出您遇到的异常.

所以这里的解决方案(或’技巧’)将在单元测试时替换默认的IAssembliesResolver.我认为旋转变压器看起来像这样：

public class TestAssembliesResolver : IAssembliesResolver
{
    public ICollection<Assembly> GetAssemblies()
    {
        return AppDomain.CurrentDomain.GetAssemblies();
    }
}

[TestMethod]
public void TestMethod1()
{
    // Replace the original IAssembliesResolver.
    GlobalConfiguration.Configuration.Services.Replace(typeof(IAssembliesResolver),new TestAssembliesResolver());

    var container = SimpleInjectorWebApiInitializer.BuildContainer();

    container.Verify();
}

你不得不处理这个问题有点不幸,特别是因为Simple Injector的设计是可测试的.我们似乎忽略了这一点,将RegisterWebApiControllers扩展方法与Web API深深地集成在一起.我们必须退后一步,思考如何更轻松地验证单元测试中的Web API配置.