How to: Find Attributes of Siblings with a Specific Name (XPath-LINQ to XML)
This topic shows how to find all attributes of the siblings of the context node. Only attributes with a specific name are returned in the collection.
The XPath expression is:
../Book/@id
Example
This example first finds a Book element, and then finds all sibling elements named Book, and then finds all attributes named id. The result is a collection of attributes.
This example uses the following XML document: Sample XML File: Books (LINQ to XML).
XDocument books = XDocument.Load("Books.xml");
XElement book =
books
.Root
.Element("Book");
// LINQ to XML query
IEnumerable<XAttribute> list1 =
from el in book.Parent.Elements("Book")
select el.Attribute("id");
// XPath expression
IEnumerable<XAttribute> list2 =
((IEnumerable)book.XPathEvaluate("../Book/@id")).Cast<XAttribute>();
if (list1.Count() == list2.Count() &&
list1.Intersect(list2).Count() == list1.Count())
Console.WriteLine("Results are identical");
else
Console.WriteLine("Results differ");
foreach (XAttribute el in list1)
Console.WriteLine(el);
Dim books as XDocument = XDocument.Load("Books.xml")
Dim book As XElement = books.Root.<Book>(0)
' LINQ to XML query
Dim list1 As IEnumerable(Of XAttribute) = _
From el In book.Parent.<Book> _
Select el.Attribute("id")
' XPath expression
Dim list2 As IEnumerable(Of XAttribute) = DirectCast(book. _
XPathEvaluate("../Book/@id"), IEnumerable).Cast(Of XAttribute)()
If list1.Count() = list2.Count() And _
(list1.Intersect(list2)).Count() = list1.Count() Then
Console.WriteLine("Results are identical")
Else
Console.WriteLine("Results differ")
End If
For Each el As XAttribute In list1
Console.WriteLine(el)
Next
This example produces the following output:
Results are identical
id="bk101"
id="bk102"