xml - Powershell出现错误无法将值 “System.Xml.XPathNodeList”转换为键入“System.Xml.XmlDocument

Question

我有以下powershell代码，该代码选择具有 namespace 的xml节点。

$ns = new-Object System.Xml.XmlNamespaceManager $doc.NameTable
$ns.AddNamespace("dns", "http://www.nlog-project.org/schemas/NLog.xsd")
$obj3 = $doc.SelectNodes('//dns:nlog',$ns)

但是我收到以下错误:

Cannot convert value "System.Xml.XPathNodeList" to type "System.Xml.XmlDocument". Error: "The specified node cannot be inserted as the valid child of this node, because the specified node is the wrong type." At C:\MetacubeAutoBuildDeployment\PowershellScripts\PEStandAloneWebConfigReplace.ps1:15 char:1 + $obj3 = $doc.SelectNodes('//dns:nlog',$ns) + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : MetadataError: (:) [], ArgumentTransformationMetadataException + FullyQualifiedErrorId : RuntimeException

此错误有任何具体原因吗？
我必须获取$ doc中突出显示的connectionString标记的值。
$ doc包含:

<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
    <section name="nlog" type="NLog.Config.ConfigSectionHandler, NLog" />
    <section name="ciel" type="Ciel.Application.Common.CielConfigSectionHandler, Ciel.Application" />
    <sectionGroup name="elmah">
      <section name="security" requirePermission="false" type="Elmah.SecuritySectionHandler, Elmah" />
      <section name="errorLog" requirePermission="false" type="Elmah.FallbackErrorLogSectionHandler, Elmah.FallbackErrorLog" />
      <section name="errorMail" requirePermission="false" type="Elmah.ErrorMailSectionHandler, Elmah" />
      <section name="errorFilter" requirePermission="false" type="Elmah.ErrorFilterSectionHandler, Elmah" />
    </sectionGroup>
  </configSections>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
  </startup>
  <nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <!-- Load NLog extensions from the *.dll file -->
    <extensions>
      <add assembly="NLog.Web" />
      <add assembly="NLog.Extended" />
    </extensions>
    <!-- Targets or Output -->
    <targets>
      <default-wrapper xsi:type="AsyncWrapper" />
      <!-- File Target -->
      <target name="sqllog" xsi:type="File" fileName="App_Data/NLoggerLogs/PESql.log" archiveFileName="App_Data/log/CielSql.{#####}.log" maxArchiveFiles="100" archiveAboveSize="10485760" archiveNumbering="Sequence" concurrentWrites="true" keepFileOpen="false" encoding="UTF-8">
        <layout xsi:type="CSVLayout" delimiter="Tab">
          <column name="level" layout="${level:uppercase=true}" />
          <column name="aspnet-sessionid" layout="${aspnet-sessionid}" />
          <column name="aspnet-request(ASP.NET_SessionId)" layout="${aspnet-request:cookie=ASP.NET_SessionId}" />
          <column name="aspnet-request(HTTP_USER_AGENT)" layout="${aspnet-request:serverVariable=HTTP_USER_AGENT}" />
          <column name="aspnet-request(REMOTE_ADDR)" layout="${aspnet-request:serverVariable=REMOTE_ADDR}" />
          <column name="aspnet-request(REMOTE_HOST)" layout="${aspnet-request:serverVariable=REMOTE_HOST}" />
          <column name="date" layout="${longdate}" />
          <column name="message" layout="${message:exceptionSeparator=|:withException=true}" />
          <column name="aspnet-user-identity" layout="${aspnet-user-identity}" />
        </layout>
      </target>
      <target name="debuglog" xsi:type="File" fileName="App_Data/NLoggerLogs/PE.log" archiveFileName="App_Data/log/Ciel.{#####}.log" maxArchiveFiles="100" archiveAboveSize="2097152" archiveNumbering="Sequence" concurrentWrites="true" keepFileOpen="false" encoding="UTF-8">
        <layout xsi:type="CSVLayout" delimiter="Tab">
          <column name="date" layout="${longdate}" />
          <column name="level" layout="${level:uppercase=true}" />
          <column name="asp-application" layout="${asp-application}" />
          <column name="asp-request" layout="${asp-request:cookie=String:serverVariable=String:queryString=String:item=String:form=String}" />
          <column name="asp-session" layout="${asp-session:variable=String}" />
          <column name="aspnet-sessionid" layout="${aspnet-sessionid}" />
          <column name="aspnet-session" layout="${aspnet-session:variable=Sring}" />
          <column name="aspnet-application" layout="${aspnet-application:variable=String}" />
          <column name="aspnet-request" layout="${aspnet-request:cookie=String:serverVariable=String:queryString=String:item=String:form=String}" />
          <column name="aspnet-request(ASP.NET_SessionId)" layout="${aspnet-request:cookie=ASP.NET_SessionId}" />
          <column name="aspnet-request(HTTP_USER_AGENT)" layout="${aspnet-request:serverVariable=HTTP_USER_AGENT}" />
          <column name="aspnet-request(URL)" layout="${aspnet-request:serverVariable=URL}" />
          <column name="aspnet-request(REMOTE_ADDR)" layout="${aspnet-request:serverVariable=REMOTE_ADDR}" />
          <column name="aspnet-request(REMOTE_HOST)" layout="${aspnet-request:serverVariable=REMOTE_HOST}" />
          <column name="aspnet-user-authtype" layout="${aspnet-user-authtype}" />
          <column name="aspnet-user-identity" layout="${aspnet-user-identity}" />
          <column name="threadid" layout="${threadid}" />
          <column name="stacktrace" layout="${stacktrace:topFrames=2}" />
          <column name="machinename" layout="${machinename}" />
          <column name="document-uri" layout="${document-uri}" />
          <column name="callsite" layout="${callsite:className=true:fileName=true:includeSourcePath=true:methodName=true}" />
          <column name="message" layout="${message:exceptionSeparator=|:withException=true}" />
        </layout>
      </target>
      <target name="accesslog" xsi:type="File" fileName="${basedir}/APP_Data/NLoggerLogs/PEAccess.log" archiveFileName="${basedir}/App_Data/log/CielAccess.{#####}.log" maxArchiveFiles="100" archiveAboveSize="2097152" archiveNumbering="Sequence" concurrentWrites="true" keepFileOpen="false" encoding="UTF-8">
        <layout xsi:type="CSVLayout" delimiter="Tab">
          <column name="aspnet-sessionid" layout="${aspnet-sessionid}" />
          <column name="aspnet-request(HTTP_USER_AGENT)" layout="${aspnet-request:serverVariable=HTTP_USER_AGENT}" />
          <column name="aspnet-request(REMOTE_ADDR)" layout="${aspnet-request:serverVariable=REMOTE_ADDR}" />
          <column name="aspnet-request(REMOTE_HOST)" layout="${aspnet-request:serverVariable=REMOTE_HOST}" />
          <column name="date" layout="${longdate}" />
          <column name="message" layout="${message:exceptionSeparator=|:withException=true}" />
        </layout>
      </target>
      <target name="database" xsi:type="Database">
        <!--
        Remarks:
          The appsetting layouts require the NLog.Extended assembly.
          The aspnet-* layouts require the NLog.Web assembly.
          The Application value is determined by an AppName appSetting in Web.config.
          The "NLogDb" connection string determines the database that NLog write to.
          The create dbo.Log script in the comment below must be manually executed.
        -->
        <!--<connectionStringName>SQLServer_develop</connectionStringName>-->
        <dbProvider>System.Data.SqlClient</dbProvider>
        **<connectionString>server=server;database=database;integrated security=False;User ID=userid;Password=password</connectionString>**
        <commandText>
          insert into [CIEL].[DPR_JOBINSTANCEDETAILS] (
          JOBID, JOBINSTANCEID, STEPINSTANCEID,STEPID,LOGTYPE, MESSAGETYPE, MESSAGE, PARENTID,LOGGEDON
          )
          values (
          @JOBID, @JOBINSTANCEID, @STEPINSTANCEID, @STEPID, @LOGTYPE,@MESSAGETYPE, @MESSAGE, @PARENTID, @LOGGEDON
          );
        </commandText>
        <parameter name="@JOBID" layout="${event-properties:item=JOBID}" />
        <parameter name="@JOBINSTANCEID" layout="${event-properties:item=JOBINSTANCEID}" />
        <parameter name="@STEPINSTANCEID" layout="${event-properties:item=STEPINSTANCEID}" />
        <parameter name="@STEPID" layout="${event-properties:item=STEPID}" />
        <parameter name="@LOGTYPE" layout="${event-properties:item=LOGTYPE}" />
        <parameter name="@MESSAGETYPE" layout="${event-properties:item=MESSAGETYPE}" />
        <parameter name="@MESSAGE" layout="${event-properties:item=MESSAGE}" />
        <parameter name="@PARENTID" layout="${event-properties:item=PARENTID}" />
        <parameter name="@LOGGEDON" layout="${date}" />
      </target>
      <target name="sqllog_table" xsi:type="Database">
        <!--Remarks:
          The appsetting layouts require the NLog.Extended assembly.
          The aspnet-* layouts require the NLog.Web assembly.
          The Application value is determined by an AppName appSetting in Web.config.
          The "NLogDb" connection string determines the database that NLog write to.
          The create dbo.Log script in the comment below must be manually executed.-->
        <connectionStringName>NLogConnection</connectionStringName>
      </target>
    </targets>
    <!-- Rules for calling the appropriate Target -->
    <rules>
      <logger name="DebugLogger" minlevel="Debug" writeTo="debuglog" />
      <logger name="SqlLogger" minlevel="Debug" writeTo="sqllog" />
      <logger name="AccessLogger" minlevel="Info" writeTo="accesslog" />
      <logger name="PROCESSENGINEDB" minlevel="Trace" writeTo="database" />
    </rules>
  </nlog>
</configuration>

Answer 1

您可以按照WOxxOm's comments的建议使用GetElementsByTagName。很优雅但是，潜在的问题可能是由于更改xml结构，重新排序或多个connectionString引起的。

您可以对XML进行点索引。优点是它更加明确。缺点是它更明确。

如果您更改connectionString的路径，则需要更新，而GetElementsByTagName则不需要。但是，这对于显式定义您感兴趣的标记以及使您可以方便地访问该标记中的其他信息更好。我发现它通常更直观。

$dbdetails = $doc.configuration.nlog.targets.target | Where-Object {$_.name -eq "database"}
$dbdetails.ConnectionString

您的代码在PowerShell v5.1上没有给我同样的错误。我复制了$ doc的代码，并使用here-string将其分配给变量:

[xml]$doc = @"
    ...
"@

编辑:

两全其美？

$dbdetails = $doc.GetElementsByTagName("target") | Where-Object {$_.name -eq "database"}

Get-member ，显示可访问的属性