how to read a xml?

Question

<package version="2.0" xmlns="http://www.idpf.org/2007/opf" unique-identifier="bookid">
<metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opf="http://www.idpf.org/2007/opf">
<dc:identifier id="bookid">easypub-ed863743</dc:identifier>
<meta name="cover" content="cover-image"/>
</metadata>
</package>

I can get the metadata node how to get the dc:identifier node?

metadataNode.SelectSingleNode("/dc:identifier) is null

Answer 1

@mc , Based on my test, you could try the following code to get identifier from metadata node.

  private void button1_Click(object sender, EventArgs e)  
        {  
            string path = "D:\\test.xml";  
            XNamespace xn1 = "http://www.idpf.org/2007/opf";  
            XDocument doc = XDocument.Load(path);  
            XNamespace xn2 = "http://purl.org/dc/elements/1.1/";  
            var result = doc.Descendants(xn1 + "metadata");  
  
            foreach (var item in result.Descendants(xn2+ "identifier"))  
            {  
                textBox1.Text = item.Value;  
                textBox2.Text = item.Attribute("id").Value;  
                //Console.WriteLine(item.Value);  
                //Console.WriteLine(item.Attribute("id").Value);  
            }  
  
  
        }  

Also, I think another method will be simpler if we don't consider that we need to get identifier from metadata node.

 private void button1_Click(object sender, EventArgs e)  
        {  
            string path = "D:\\test.xml";  
            XDocument doc = XDocument.Load(path);  
            XNamespace xn2 = "http://purl.org/dc/elements/1.1/";  
            
            var item= doc.Descendants(xn2 + "identifier").FirstOrDefault();  
            textBox1.Text = item.Value;  
            textBox2.Text = item.Attribute("id").Value;  
  
  
        }  

The both methods can get the following result:

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Answer 2

Hi @mc ,

Please check the the link below:

https://learn.microsoft.com/en-us/dotnet/api/system.xml.xmlnode.selectsinglenode?view=net-6.0

Hope this will help. Thanks!

Answer 3

You just need to make sure you add namespaces for elements you're selecting using XmlNamespaceManager like the example that nasreen linked to:

using System.Xml;

string xml = @"
<package version=""2.0"" xmlns=""http://www.idpf.org/2007/opf"" unique-identifier=""bookid"">
    <metadata xmlns:dc=""http://purl.org/dc/elements/1.1/"" xmlns:opf=""http://www.idpf.org/2007/opf"">
        <dc:identifier id=""bookid"">easypub-ed863743</dc:identifier>
        <meta name=""cover"" content=""cover-image""/>
    </metadata>
</package>
".Trim();

XmlDocument doc = new XmlDocument();
doc.LoadXml(xml);

XmlNamespaceManager nsMgr = new XmlNamespaceManager(doc.NameTable);
nsMgr.AddNamespace("df", "http://www.idpf.org/2007/opf"); // Default namespace to select <metadata>
nsMgr.AddNamespace("dc", "http://purl.org/dc/elements/1.1/");

XmlElement root = doc.DocumentElement;
XmlNode identifier = root.SelectSingleNode("//dc:identifier", nsMgr);
XmlNode metadata = root.SelectSingleNode("//df:metadata", nsMgr);

Console.WriteLine(identifier.InnerText);