Understand xml namespaces used with linq-CodePudding

I try to get informations from an xml file and so far I am quite good with the navigation via

doc.Element("foo1").Element("foo2").Value

But now I am running into a wall and I think it is because of the namespace. I use this code snippet to filter a specific part out of my xml doc:

 XNamespace xmlns = "http://www.siemens.com/automation/Openness/SW/Interface/v4";
 IEnumerable<XElement> de =
      from el in doc.Descendants(xmlns   "Section")
      where el.Attribute("Name").Value == "Input"
      select el;

The namespace is given and the resulting XElement is the followed one:

<Section Name="Input" xmlns="http://www.siemens.com/automation/Openness/SW/Interface/v4">
  <Member Name="STARTTASTER" Datatype="Bool" Remanence="NonRetain" Accessibility="Public">
    <AttributeList>
      <BooleanAttribute Name="ExternalAccessible" SystemDefined="true">true</BooleanAttribute>
      <BooleanAttribute Name="ExternalVisible" SystemDefined="true">true</BooleanAttribute>
      <BooleanAttribute Name="ExternalWritable" SystemDefined="true">true</BooleanAttribute>
      <BooleanAttribute Name="UserVisible" Informative="true" SystemDefined="true">true</BooleanAttribute>
      <BooleanAttribute Name="UserReadOnly" Informative="true" SystemDefined="true">false</BooleanAttribute>
      <BooleanAttribute Name="UserDeletable" Informative="true" SystemDefined="true">true</BooleanAttribute>
    </AttributeList>
  </Member>
</Section>

That is exactly what I want to have and I can save it at root

Now I use

var foo = root.Element(xmlns   "Section");
Console.WriteLine(foo);

And I would expect to get this

 <Member Name="STARTTASTER" Datatype="Bool" Remanence="NonRetain" Accessibility="Public">
        <AttributeList>
          <BooleanAttribute Name="ExternalAccessible" SystemDefined="true">true</BooleanAttribute>
          <BooleanAttribute Name="ExternalVisible" SystemDefined="true">true</BooleanAttribute>
          <BooleanAttribute Name="ExternalWritable" SystemDefined="true">true</BooleanAttribute>
          <BooleanAttribute Name="UserVisible" Informative="true" SystemDefined="true">true</BooleanAttribute>
          <BooleanAttribute Name="UserReadOnly" Informative="true" SystemDefined="true">false</BooleanAttribute>
          <BooleanAttribute Name="UserDeletable" Informative="true" SystemDefined="true">true</BooleanAttribute>
        </AttributeList>
 </Member>

But I just get nothing. Now my first question would be why and secondly, how could I achieve my expected outcome.

I would be also happy if there is a nicer/more practical way. I actually want to store the value "STARTTASTER" into a variable.

CodePudding user response：

Please try the following solution.

I saved your XML as a e:\Temp\Aschenauer.xml file:

<Section Name="Input" xmlns="http://www.siemens.com/automation/Openness/SW/Interface/v4">
    <Member Name="STARTTASTER" Datatype="Bool" Remanence="NonRetain" Accessibility="Public">
        <AttributeList>
            <BooleanAttribute Name="ExternalAccessible" SystemDefined="true">true</BooleanAttribute>
            <BooleanAttribute Name="ExternalVisible" SystemDefined="true">true</BooleanAttribute>
            <BooleanAttribute Name="ExternalWritable" SystemDefined="true">true</BooleanAttribute>
            <BooleanAttribute Name="UserVisible" Informative="true" SystemDefined="true">true</BooleanAttribute>
            <BooleanAttribute Name="UserReadOnly" Informative="true" SystemDefined="true">false</BooleanAttribute>
            <BooleanAttribute Name="UserDeletable" Informative="true" SystemDefined="true">true</BooleanAttribute>
        </AttributeList>
    </Member>
</Section>

void Main()
{
    const string filename = @"e:\Temp\Aschenauer.xml";

    XDocument xdoc = XDocument.Load(filename);
    XNamespace ns = xdoc.Root.GetDefaultNamespace();

    var NameAttr = xdoc.Descendants(ns   "Member")
        .Attributes("Name").FirstOrDefault().Value;

    Console.WriteLine($"Name='{NameAttr}'");
}

Output

Name='STARTTASTER'