我想对csproj文件进行一些路径更改以配置源代码控制。而不是手工完成，我想Id迭代csproj文件，并在每个csproj中使用Linq-to-Xml根据需要改变构建和引用路径。
所以我环顾四周，目前正在尝试使用：
public void Read(string fileName)
{
XDocument doc = XDocument.Load(fileName);
foreach (XElement el in doc.Root.Elements())
{
Console.WriteLine("{0} {1}", el.Name, el.Attribute("id").Value);
Console.WriteLine(" Attributes:");
foreach (XAttribute attr in el.Attributes())
Console.WriteLine(" {0}", attr);
Console.WriteLine(" Elements:");
foreach (XElement element in el.Elements())
Console.WriteLine(" {0}: {1}", element.Name, element.Value);
}
}
根据此SO问题的接受答案xml-parsing-read-a-simple-xml-file-and-retrieve-values。 但是当行
foreach (XElement el in doc.Root.Elements())
我在调用Elements时得到一个空引用错误。我也尝试过调用Nodes，Descendants等，但它们都是空的。文档。 doc.Root确实返回了proj文件中的所有内容（顶部的命名空间行除外），所以有些东西我只是没有正确使用它。
那么我做错了什么？我希望Elements能够返回一个XML片段的集合，我可以走路或过滤掉我想要的片段，即
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
更新
所以这是一个csproj的例子：
<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<PropertyGroup>
<Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
<Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
<ProductVersion>8.0.30703</ProductVersion>
<SchemaVersion>2.0</SchemaVersion>
<ProjectGuid>{2CCAB46D-7A7C-4C65-B6D2-DC2D4049FCD9}</ProjectGuid>
<OutputType>Library</OutputType>
<AppDesignerFolder>Properties</AppDesignerFolder>
<RootNamespace>Basd.Core</RootNamespace>
<AssemblyName>Basd.Core</AssemblyName>
<TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
<FileAlignment>512</FileAlignment>
<TargetFrameworkProfile>
</TargetFrameworkProfile>
</PropertyGroup>
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
<DebugSymbols>true</DebugSymbols>
<DebugType>full</DebugType>
<Optimize>false</Optimize>
<OutputPath>..\..\Basd.Bin\AnyCPU\Release\</OutputPath>
<DefineConstants>DEBUG;TRACE</DefineConstants>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
<PlatformTarget>AnyCPU</PlatformTarget>
<Prefer32Bit>false</Prefer32Bit>
</PropertyGroup>
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
<DebugType>pdbonly</DebugType>
<Optimize>true</Optimize>
<OutputPath>..\..\Basd.Bin\AnyCPU\Release\</OutputPath>
<DefineConstants>TRACE</DefineConstants>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
<PlatformTarget>AnyCPU</PlatformTarget>
<Prefer32Bit>false</Prefer32Bit>
</PropertyGroup>
<PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|x86'">
<PlatformTarget>x86</PlatformTarget>
<OutputPath>..\..\Basd.Bin\x86\Debug\</OutputPath>
<DebugType>full</DebugType>
<Prefer32Bit>false</Prefer32Bit>
</PropertyGroup>
<PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x86'">
<PlatformTarget>AnyCPU</PlatformTarget>
<OutputPath>..\..\Basd.Bin\AnyCPU\Release\</OutputPath>
<DefineConstants>
</DefineConstants>
<DebugType>pdbonly</DebugType>
<DebugSymbols>true</DebugSymbols>
<Prefer32Bit>false</Prefer32Bit>
</PropertyGroup>
<ItemGroup>
<Reference Include="Microsoft.VisualBasic" />
<Reference Include="System" />
<Reference Include="System.Configuration" />
<Reference Include="System.Core" />
<Reference Include="System.Xml.Linq" />
<Reference Include="System.Data.DataSetExtensions" />
<Reference Include="Microsoft.CSharp" />
<Reference Include="System.Data" />
<Reference Include="System.Xml" />
</ItemGroup>
<ItemGroup>
<Compile Include="Activation\ActivationExtensions.cs" />
<Compile Include="Activation\ActivationMetaDataList.cs" />
<Compile Include="Activation\ActivationProviderFactory.cs" />
<Compile Include="Activation\ActivationMetaDataConfigurationProvider.cs" />
<Compile Include="Activation\ActivationMetaDataConfigurationProviderSection.cs" />
<Compile Include="Activation\ActivationMetaDataProvider.cs" />
<Compile Include="Activation\IActivationMetaData.cs" />
<Compile Include="Activation\ActivationMetaData.cs" />
<Compile Include="Activation\IActivationMetaDataProvider.cs" />
<Compile Include="Collections\DomainList.cs" />
<Compile Include="DateTime\GenerationDateRange.cs" />
<Compile Include="DateTime\DateBlitterExtensions.cs" />
<Compile Include="Dto\DTOStub.generic.cs" />
<Compile Include="Dto\Tabulation.cs" />
<Compile Include="Dto\TabulatedItem.cs" />
<Compile Include="Dto\DTOStub.cs" />
<Compile Include="Environment\EnvironmentContext.cs" />
<Compile Include="Events\Delegates.cs" />
<Compile Include="Activation\ActivationHelper.cs" />
<Compile Include="Helpers\ObjectScrubber.cs" />
<Compile Include="Helpers\SmtpHelper.cs" />
<Compile Include="Interfaces\INameHolder.cs" />
<Compile Include="Interfaces\IFrame.cs" />
<Compile Include="Events\FrameEventArgs.cs" />
<Compile Include="Events\PayloadedEventArgs.cs" />
<Compile Include="Helpers\DateHelper.cs" />
<Compile Include="Helpers\EnumerableDataSources.cs" />
<Compile Include="Helpers\EnumHelper.cs" />
<Compile Include="Helpers\StringsHelper.cs" />
<Compile Include="Interfaces\IIndexable.cs" />
<Compile Include="Interfaces\INameable.cs" />
<Compile Include="Collections\NamedList.cs" />
<Compile Include="Interfaces\IText.cs" />
<Compile Include="Events\KeyChangedEventArgs.cs" />
<Compile Include="DateTime\DateRange.cs" />
<Compile Include="DateTime\EntityDateRange.cs">
<SubType>Code</SubType>
</Compile>
<Compile Include="DateTime\IMinimumBoundedDateRange.cs" />
<Compile Include="DateTime\IDateRange.cs" />
<Compile Include="Enumerations.cs" />
<Compile Include="DateTime\IEntityDateRange.cs" />
<Compile Include="Interfaces\IUserNotifier.cs" />
<Compile Include="Collections\IXtendedEnumerable.cs" />
<Compile Include="Membership.cs" />
<Compile Include="DateTime\MinimumBoundedDateRange.cs" />
<Compile Include="Properties\AssemblyInfo.cs" />
<Compile Include="Properties\Resources.Designer.cs">
<AutoGen>True</AutoGen>
<DesignTime>True</DesignTime>
<DependentUpon>Resources.resx</DependentUpon>
</Compile>
<Compile Include="SeriesCube.cs" />
<Compile Include="Collections\XList.cs" />
</ItemGroup>
<ItemGroup>
<Folder Include="Compression\" />
</ItemGroup>
<ItemGroup>
<EmbeddedResource Include="Properties\Resources.resx">
<Generator>ResXFileCodeGenerator</Generator>
<LastGenOutput>Resources.Designer.cs</LastGenOutput>
</EmbeddedResource>
</ItemGroup>
<Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
<!-- To modify your build process, add your task inside one of the targets below and uncomment it.
Other similar extension points exist, see Microsoft.Common.targets.
<Target Name="BeforeBuild">
</Target>
<Target Name="AfterBuild">
</Target>
-->
</Project>
从中间窗口设置断点
foreach (XElement el in doc.Root.Elements())
?doc.Root.ToString(); "<Project ToolsVersion=\"4.0\" DefaultTargets=\"Build\" xmlns=\"http://schemas.microsoft.com/developer/msbuild/2003\">\r\n <PropertyGroup>\r\n <Configuration Condition=\" '$(Configuration)'
== '' \">Debug</Configuration>\r\n <Platform Condition=\" '$(Platform)' == '' \">AnyCPU</Platform>\r\n <ProductVersion>8.0.30703</ProductVersion>\r\n <SchemaVersion>2.0</SchemaVersion>\r\n <ProjectGuid>{2CCAB46D-7A7C-4C65-B6D2-DC2D4049FCD9}</ProjectGuid>\r\n <OutputType>Library</OutputType>\r\n <AppDesignerFolder>Properties</AppDesignerFolder>\r\n <RootNamespace>Basd.Core</RootNamespace>\r\n <AssemblyName>Basd.Core</AssemblyName>\r\n <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>\r\n <FileAlignment>512</FileAlignment>\r\n <TargetFrameworkProfile></TargetFrameworkProfile>\r\n </PropertyGroup>\r\n <PropertyGroup Condition=\" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' \">\r\n <DebugSymbols>true</DebugSymbols>\r\n <DebugType>full</DebugType>\r\n <Optimize>false</Optim ize>\r\n <OutputPath>..\\..\\Basd.Bin\\AnyCPU\\Release\\</OutputPath>\r\n <DefineConstants>DEBUG;TRACE</DefineConstants>\r\n <ErrorReport>prompt</ErrorReport>\r\n <WarningLevel>4</WarningLevel>\r\n <PlatformTarget>AnyCPU</PlatformTarget>\r\n <Prefer32Bit>false</Prefer32Bit>\r\n </PropertyGroup>\r\n <PropertyGroup Condition=\" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' \">\r\n <DebugType>pdbonly</DebugType>\r\n <Optimize>true</Optimize>\r\n <OutputPath>..\\..\\Basd.Bin\\AnyCPU\\Release\\</OutputPath>\r\n <DefineConstants>TRACE</DefineConstants>\r\n <ErrorReport>prompt</ErrorReport>\r\n <WarningLevel>4</WarningLevel>\r\n <PlatformTarget>AnyCPU</PlatformTarget>\r\n <Prefer32Bit>false</Prefer32Bit>\r\n </PropertyGroup>\r\n <PropertyGroup Condition=\"'$(Configuration)|$(Platform)' == 'Debug|x86'\">\r\n <PlatformTarget>x86</PlatformTarget>\r\n <OutputPath>..\\..\\Basd.Bin\\x86\\Debug\\</OutputPath>\r\n <DebugType>full</DebugType>\r\n <Prefer32Bit>fals e</Prefer32Bit>\r\n </PropertyGroup>\r\n <PropertyGroup Condition=\"'$(Configuration)|$(Platform)' == 'Release|x86'\">\r\n <PlatformTarget>AnyCPU</PlatformTarget>\r\n <OutputPath>..\\..\\Basd.Bin\\AnyCPU\\Release\\</OutputPath>\r\n <DefineConstants></DefineConstants>\r\n <DebugType>pdbonly</DebugType>\r\n <DebugSymbols>true</DebugSymbols>\r\n <Prefer32Bit>false</Prefer32Bit>\r\n </PropertyGroup>\r\n <ItemGroup>\r\n <Reference Include=\"Microsoft.VisualBasic\" />\r\n <Reference Include=\"System\" />\r\n <Reference Include=\"System.Configuration\" />\r\n <Reference Include=\"System.Core\" />\r\n <Reference Include=\"System.Xml.Linq\" />\r\n <Reference Include=\"System.Data.DataSetExtensions\" />\r\n <Reference Include=\"Microsoft.CSharp\" />\r\n <Reference Include=\"System.Data\" />\r\n <Reference Include=\"System.Xml\" />\r\n </ItemGroup>\r\n <ItemGroup>\r\n <Compile Include=\"Activation\\ActivationExtensions.cs\" />\r\n <Compile Include=\"Activation\\Act ivationMetaDataList.cs\" />\r\n <Compile Include=\"Activation\\ActivationProviderFactory.cs\" />\r\n <Compile Include=\"Activation\\ActivationMetaDataConfigurationProvider.cs\" />\r\n <Compile Include=\"Activation\\ActivationMetaDataConfigurationProviderSection.cs\" />\r\n <Compile Include=\"Activation\\ActivationMetaDataProvider.cs\" />\r\n <Compile Include=\"Activation\\IActivationMetaData.cs\" />\r\n <Compile Include=\"Activation\\ActivationMetaData.cs\" />\r\n <Compile Include=\"Activation\\IActivationMetaDataProvider.cs\" />\r\n <Compile Include=\"Collections\\DomainList.cs\" />\r\n <Compile Include=\"DateTime\\GenerationDateRange.cs\" />\r\n <Compile Include=\"DateTime\\DateBlitterExtensions.cs\" />\r\n <Compile Include=\"Dto\\DTOStub.generic.cs\" />\r\n <Compile Include=\"Dto\\Tabulation.cs\" />\r\n <Compile Include=\"Dto\\TabulatedItem.cs\" />\r\n <Compile Include=\"Dto\\DTOStub.cs\" />\r\n <Compile Include=\"Environment\\EnvironmentContext.cs\" />\r\n <C ompile Include=\"Events\\Delegates.cs\" />\r\n <Compile Include=\"Activation\\ActivationHelper.cs\" />\r\n <Compile Include=\"Helpers\\ObjectScrubber.cs\" />\r\n <Compile Include=\"Helpers\\SmtpHelper.cs\" />\r\n <Compile Include=\"Interfaces\\INameHolder.cs\" />\r\n <Compile Include=\"Interfaces\\IFrame.cs\" />\r\n <Compile Include=\"Events\\FrameEventArgs.cs\" />\r\n <Compile Include=\"Events\\PayloadedEventArgs.cs\" />\r\n <Compile Include=\"Helpers\\DateHelper.cs\" />\r\n <Compile Include=\"Helpers\\EnumerableDataSources.cs\" />\r\n <Compile Include=\"Helpers\\EnumHelper.cs\" />\r\n <Compile Include=\"Helpers\\StringsHelper.cs\" />\r\n <Compile Include=\"Interfaces\\IIndexable.cs\" />\r\n <Compile Include=\"Interfaces\\INameable.cs\" />\r\n <Compile Include=\"Collections\\NamedList.cs\" />\r\n <Compile Include=\"Interfaces\\IText.cs\" />\r\n <Compile Include=\"Events\\KeyChangedEventArgs.cs\" />\r\n <Compile Include=\"DateTime\\DateRange.cs\" />\r\n <Co mpile Include=\"DateTime\\EntityDateRange.cs\">\r\n <SubType>Code</SubType>\r\n </Compile>\r\n <Compile Include=\"DateTime\\IMinimumBoundedDateRange.cs\" />\r\n <Compile Include=\"DateTime\\IDateRange.cs\" />\r\n <Compile Include=\"Enumerations.cs\" />\r\n <Compile Include=\"DateTime\\IEntityDateRange.cs\" />\r\n <Compile Include=\"Interfaces\\IUserNotifier.cs\" />\r\n <Compile Include=\"Collections\\IXtendedEnumerable.cs\" />\r\n <Compile Include=\"Membership.cs\" />\r\n <Compile Include=\"DateTime\\MinimumBoundedDateRange.cs\" />\r\n <Compile Include=\"Properties\\AssemblyInfo.cs\" />\r\n <Compile Include=\"Properties\\Resources.Designer.cs\">\r\n <AutoGen>True</AutoGen>\r\n <DesignTime>True</DesignTime>\r\n <DependentUpon>Resources.resx</DependentUpon>\r\n </Compile>\r\n <Compile Include=\"SeriesCube.cs\" />\r\n <Compile Include=\"Collections\\XList.cs\" />\r\n </ItemGroup>\r\n <ItemGroup>\r\n <Folder Include=\"Compression\\\" />\r\n </Item Group>\r\n <ItemGroup>\r\n <EmbeddedResource Include=\"Properties\\Resources.resx\">\r\n <Generator>ResXFileCodeGenerator</Generator>\r\n <LastGenOutput>Resources.Designer.cs</LastGenOutput>\r\n </EmbeddedResource>\r\n </ItemGroup>\r\n <Import Project=\"$(MSBuildToolsPath)\\Microsoft.CSharp.targets\" />\r\n <!-- To modify your build process, add your task inside one of the targets below and uncomment it. \r\n Other similar extension points exist, see Microsoft.Common.targets.\r\n <Target Name=\"BeforeBuild\">\r\n </Target>\r\n <Target Name=\"AfterBuild\">\r\n </Target>\r\n -->\r\n</Project>"
?doc.Root.Name; {{http://schemas.microsoft.com/developer/msbuild/2003}Project}
hashCode: 541551665
localName: "Project"
LocalName: "Project"
Namespace: {http://schemas.microsoft.com/developer/msbuild/2003}
NamespaceName: "http://schemas.microsoft.com/developer/msbuild/2003"
ns: {http://schemas.microsoft.com/developer/msbuild/2003}
?doc.Root.Descendants(); {System.Xml.Linq.XContainer.GetDescendants}
name: null
self: false
System.Collections.Generic.IEnumerator<System.Xml.Linq.XElement>.Current: null
System.Collections.IEnumerator.Current: null ?doc.Root.Nodes(); {System.Xml.Linq.XContainer.Nodes}
System.Collections.Generic.IEnumerator<System.Xml.Linq.XNode>.Current: null
System.Collections.IEnumerator.Current: null ?doc.Root.Attributes();
答案 0 :(得分：1)
你在这一行得到例外：
Console.WriteLine("{0} {1}", el.Name, el.Attribute("id").Value);
因为根目录中至少有第一个子元素，所以PropertyGroup中的id属性不包含Console.WriteLine("{0} {1}", el.Name, (string)el.Attribute("id"));
属性。
我可以认为你将这一行重写为
{{1}}
在这种情况下，您的代码不会抛出任何异常。