如何从没有属性的 XML 文件中获取节点并放入字符串列表

Question

I would like to display the tag names of child nodes without its attributes. Then those tag names (nodes) should be put in a List of string. Here's example of my XML file:

<?xml version="1.0" encoding="UTF-8"?>
<ROOT>
    <CAR>
        <ID>21</ID>
        <MANUFACTURER>Ford</MANUFACTURER>
        <MODEL>Fiesta</MODEL>
    </CAR>
    <CAR>
        <ID>22</ID>
        <MANUFACTURER>Peugeot</MANUFACTURER>
        <MODEL>508</MODEL>
    </CAR>
</ROOT>

So, the effect I want to get in a console output is shown below:

ID
MANUFACTURER
MODEL

Then I would like to store that ID, MANUFACTURER and MODEL tag names in a List of strings.

This is the code that I tried so far:

            XmlDocument xmlDocument = new XmlDocument();
            xmlDocument.PreserveWhitespace = true;
            try
            {
                xmlDocument.Load("XMLFile.xml");
            }
            catch (FileNotFoundException ex)
            {
                Console.WriteLine(ex);
            }

            Console.WriteLine(xmlDocument.OuterXml);

            XmlNodeList nodeList = xmlDocument.SelectNodes("ROOT/CAR");
            foreach(XmlNode node in nodeList)
            {
                Console.WriteLine(node.ChildNodes);
                xmlNodes.Add(node.ChildNodes.ToString());
            }

The problem is that it's not displaying the way I want to. As a result I only get two System.Xml.XmlChildNodes which seems to be corresponding to two <CAR> nodes, instead of its three child nodes, such as ID, MANUFACTURER and MODEL.

System.Xml.XmlChildNodes
System.Xml.XmlChildNodes

Adding items to a List basically adds the same thing as shown above.

What am I doing wrong?

Answer 1

You could loop through for children nodes:

1- You can define xmlNodes like a HashSet to avoid multiple tags like:

HashSet<string> xmlNodes = new HashSet<string>();

2 - Change little the code like:

....
XmlNodeList nodeList = xmlDocument.SelectNodes("ROOT/CAR");
foreach (XmlNode node in nodeList)
{
    foreach(XmlNode element in node.ChildNodes)
    {
        if (element.NodeType == XmlNodeType.Element)
            xmlNodes.Add(element.Name);
    }
}

Demo

Console.WriteLine(string.Join(", ", xmlNodes));

Result

ID, MANUFACTURER, MODEL

I hope you find this helpful.

Answer 2

If you have to use XmlDocument, then you can -

List<string> elements = new List<string>();
XmlNodeList CarNodes = xml.SelectNodes("Root/Car");
foreach(XmlNode c in CarNodes)
{
    foreach(XmlNode n in c.ChildNodes)
    {
        if (!elements.Contains(n.Name))
        {
            elements.Add(n.Name);
        }
    }
}

But I find XDocument to be much simpler and better readability.

XDocument xdoc = XDocument.Parse(yourXmlString);
List<string> elements = xdoc.Descendants("Car")
                            .DescendantNodes().OfType<XElement>()
                            .Select(x => x.Name).Distinct().ToList();

And thats all you'll need. Easy to read as well, get all the descendants of "Car" Node and get all distinct names of XElements within it.

Another way to do it -

List<string> elements = xdoc.Descendants("Car").First()
                            .DescendantNodes().OfType<XElement>()
                            .Select(x => x.Name).ToList();

In this case I have removed the "distinct" and rather got just the first Car node ONLY . You can see the difference - if by any case some other Car node has an extra element, you'll miss getting that information by doing it this way.