定义元素离 XML 的根有多远

Question

Consider an XML:

<items>
    <item id="0001" type="donut">
        <name>Cake</name>
        <ppu>0.55</ppu>
        <batters>
            <batter id="1001">Regular</batter>
            <batter id="1002">Chocolate</batter>
            <batter id="1003">Blueberry</batter>
        </batters>
        <topping id="5001">None</topping>
        <topping id="5002">Glazed</topping>
        <topping id="5005">Sugar</topping>
        <topping id="5006">Sprinkles</topping>
        <topping id="5003">Chocolate</topping>
        <topping id="5004">Maple</topping>
    </item>
</items>

items is the root, so distance == 0

item is directly under root, so the distance would be 1

name is 2 levels under so the distance would be 2

How do I define such distance dynamically for an XElement in C#?

Answer 1

You should be able to use the Parent property, counting steps until you get to the root:

public int GetElmtDepth(XDocument doc, XElement elmt)
{
    var (depth, target) = (0, elmt);

    while (target != doc.Root)
        (depth, target) = (depth + 1, target.Parent);

    return depth;
}

Answer 2

You could simplify the System.Xml.XmlTextReader.Depth example from MSDN to display the node elements and their respective depths:

// XML file to be parsed.
string xmlFilePath = @"C:\test.xml";

// Create the reader.
using XmlTextReader reader = new XmlTextReader(xmlFilePath);

// Parse the XML and display each node.
while (reader.Read())
{
    // If node type is an element
    // Display element name and depth
    if (reader.NodeType == XmlNodeType.Element)
    {
        Console.WriteLine($"Element = {reader.Name}, Depth = {reader.Depth}");
    }
}

Output:

Element = items, Depth = 0
Element = item, Depth = 1
Element = name, Depth = 2
Element = ppu, Depth = 2
Element = batters, Depth = 2
Element = batter, Depth = 3
Element = batter, Depth = 3
Element = batter, Depth = 3
Element = topping, Depth = 2
Element = topping, Depth = 2
Element = topping, Depth = 2
Element = topping, Depth = 2
Element = topping, Depth = 2
Element = topping, Depth = 2

Answer 3

Future readers may like to see a pure XPath solution to calculating element depth:

1. Select the targeted element using any method, say by id: //*[@id="1001"] .
2. Select all its ancestors: //*[@id="1001"]/ancestor::*
3. Count those ancestors: count(//*[@id="1001"]/ancestor::*) .

This returns 3 for the given XML, as expected.