I have following contents in Html Document
<opf:metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opf="http://www.idpf.org/2007/opf">
<dc:title>Book Title</dc:title>
<dc:language>en-us</dc:language>
<meta name="cover" content="My_Cover" xmlns="" />
<dc:identifier id="BookId" opf:scheme="ISBN">123456789</dc:identifier>
<dc:creator>Author Name</dc:creator>
<dc:publisher>amazon.com</dc:publisher>
<dc:subject>amazon.com</dc:subject>
<dc:date>2014-02-28T00:00:00+05:30</dc:date>
</opf:metadata>
I have to change the value of <dc:date>
attribute's value to current date. I am using HtmlAgilityPack and the code as below
var html1 = new HtmlAgilityPack.HtmlDocument();
html1.LoadHtml(OPFFile);
var links1 = html1.DocumentNode.SelectNodes("opf:metadata");
foreach (var link in links1)
{
link.Attributes["dc:date"].Value = DateTime.Now.ToString("yyyy-MM-dd");
}
var builder1 = new StringBuilder();
using (var writer = new StringWriter(builder))
{
html1.Save(writer);
}
OPFFile = builder1.ToString();
File.WriteAllText(@"D:\FindImageInFile\FindImageInFile\OPF.html", OPFFile);
But when i tried to convert i am getting this error Namespace Manager or XsltContext needed. This query has a prefix, variable, or user-defined function.
How to change its value ?
It seems that HtmlAgilityPack doesn't support XPath containing prefix.
If your html document is well-formed (valid xml), you can use XDocument or XmlDocument, both support namespace/prefix.
For example, to get <cd:date>
element from sample xml above using XDocument
:
var xdoc = XDocument.Parse(OPFFile);
//or if OPFFile is file path use : XDocument.Load(OPFFile);
XNamespace dc = "http://purl.org/dc/elements/1.1/";
var date = (string)xdoc.Root.Element(dc + "date");