使用xpath选择具有属性的所有节点

Question

I am trying to select all nodes using root.SelectNodes() with XPath . For reference, see msdn-documentation .

In the following document explained, you can also search for nodes that contain attributes (correct me if this is actually a wrong understanding).

So I used the following line of code:

XmlNodeList nodes = projectDoc.DocumentElement.SelectNodes("descendant::Compile[attribute::Include]");

And I am trying to read the following data:

<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="4.0">
    <ItemGroup>
        <Compile Include="ArrayExtensions.cs" />
        <Compile Include="ArrayIterator.cs" />
        <Compile Include="AutoInitializeAttribute.cs" />
        <Compile Include="AutoInitializePriority.cs" />
        <Compile Include="AutoRegisterAttribute.cs" />
        <Compile Include="FormattableExtensions.cs" />
        <Compile Include="Mathematics\PrimeNumbers.cs" />
    </ItemGroup>
</Project>

As shown in the code-sample above, I want to get all the XmlNodes that contain the Include-attribute. However, when I execute my code, nodes contains 0 elements.

What am I doing wrong here?

Answer 1

I suspect the reason it's failing has nothing to do with the attribute part - it's failing to find the elements at all, as you've asked for just Compile elements, whereas there are only actually Compile elements in the namespace with the URI http://schemas.microsoft.com/developer/msbuild/2003 .

Doing this with XPath probably requires the use of an XmlNamespaceManager which you'd then pass into another overload of SelectNodes . Personally I would use LINQ to XML instead though:

XDocument doc = XDocument.Load("myfile.xml");
XNamespace ns = "http://schemas.microsoft.com/developer/msbuild/2003";
var elements = doc.Descendants(ns + "Compile")
                  .Where(x => x.Attribute("Include") != null);

In general, I find LINQ to XML to be a much cleaner API than the "old" XmlDocument -based API.