.NET 搜索 xml 中的子元素

Question

I'm trying to load contents of a XML file into a list of custom types using Linq following the instructions in the official microsoft dotNet api: https://docs.microsoft.com/en-us/dotnet/api/system.collections.generic.list-1.find?view=netframework-4.8

My xml file looks like this:

<directives>
    <dir directive="Question" response="Response"></dir>
    <dir directive="Q2" response="Response2"></dir>
    <dir directive="Q3" response="Response3"></dir>
</directives>

and the importing code is pretty much the same as in the example linked above.

public static void ImportDirectives()
{
    // Create XML elements from a source file.
    XElement xTree = XElement.Load(AppDomain.CurrentDomain.BaseDirectory + "directives.xml");

    // Create an enumerable collection of the elements.
    IEnumerable<XElement> elements = xTree.Elements();

    // Evaluate each element and set set values in the book object.
    foreach (XElement el in elements)
    {
        Directive dir = new Directive();
        dir.directive = el.Attribute("directive").Value;
        IEnumerable<XElement> props = el.Elements();
        foreach (XElement p in props)
        {
            if (p.Name.ToString().ToLower() == "response")
            {
                dir.response = p.Value;
            }
        }
        Dir.Add(dir);
    }
}

The code works fine if I remove the root element but only add the root element into my list if I add one. I'd prefer having a root element just to make my XML look proper. How would I access the elements within the root element using this code?

Answer 1

If you are sure that your XML Schema is going to be fixed, you can access the attribute values of the XML elements directly.

I have attached a sample code.

public static void ImportDirectives()
    {
        string fileName = AppDomain.CurrentDomain.BaseDirectory + "directives.xml";
        // Create XML elements from a source file.
        XElement xTree = XElement.Load(fileName);

        // Create an enumerable collection of the elements.
        IEnumerable<XElement> elements = xTree.Elements();

        // Evaluate each element and set set values in the book object.
        foreach (XElement el in elements)
        {
            string directive = el.Attribute("directive").Value;
            string response = el.Attribute("response").Value;

            Console.WriteLine(directive + ":" + response);
        }
    }

Answer 2

When you add root then xml like

<Root>
  <directives>
    <dir directive="Question" response="Response"></dir>
    <dir directive="Q2" response="Response2"></dir>
    <dir directive="Q3" response="Response3"></dir>
  </directives>
</Root>

When you fetch first Elements() then

<directives>
    <dir directive="Question" response="Response"></dir>
    <dir directive="Q2" response="Response2"></dir>
    <dir directive="Q3" response="Response3"></dir>
  </directives>

Again fetch Elements() then you'll get Node

<dir directive="Question" response="Response"></dir>

Then you access attribute and values

      public static void ImportDirectives()
        {
            // Create XML elements from a source file.
            XElement xTree = XElement.Load(AppDomain.CurrentDomain.BaseDirectory + "directives.xml");

            // Create an enumerable collection of the elements.
            IEnumerable<XElement> elements = xTree.Elements();

            // Evaluate each element and set set values in the book object.
            foreach (XElement el in elements.Elements())
            {
                Directive dir = new Directive();
                dir.directive = el.Attribute("directive").Value;
                IEnumerable<XElement> props = el.Elements();
                foreach (XElement p in props)
                {
                    if (p.Name.ToString().ToLower() == "response")
                    {
                        dir.response = p.Value;
                    }
                }
                Dir.Add(dir);
            }
        }