Exception: The XPath expression evaluated to unexpected type System.Xml.Linq.XAttribute

问题

I've an XML file like below:

<Employees>
  <Employee Id="ABC001">
    <Name>Prasad 1</Name>
    <Mobile>9986730630</Mobile>
    <Address Type="Perminant">
      <City>City1</City>
      <Country>India</Country>
    </Address>
    <Address Type="Temporary">
      <City>City2</City>
      <Country>India</Country>
    </Address>
  </Employee>

Now I want get all Address Type's.

I tried like below using XPath and I'm getting exception.

var xPathString = @"//Employee/Address/@Type";
doc.XPathSelectElements(xPathString); // doc is XDocument.Load("xml file Path")

Exception: The XPath expression evaluated to unexpected type System.Xml.Linq.XAttribute.

Is there any issue with my XPath?

回答1:

Your XPath is fine (although you might want it to be more selective), but you have to adjust how you evaluate it...

XPathSelectElement(), as its name implies, should only be used to select elements.

XPathEvaluate() is more general and can be used for attributes. You can enumerate over the results, or grab the first:

var type = ((IEnumerable<object>)doc.XPathEvaluate("//Employee/Address/@Type"))
                                    .OfType<XAttribute>()
                                    .Single()
                                    .Value;

回答2:

Expanding on kjhughes's answer, I've tended to create an XElement class extension for this so that I can simply call element.XPathSelectAttribute(), which makes my calling code look a great deal clearner.

public static class XElementExtensions
{
    public static XAttribute XPathSelectAttribute(this XElement element, string xPath)
    {
        return ((IEnumerable<object>)element.XPathEvaluate(xPath)).OfType<XAttribute>().First();
    }
}

来源：https://stackoverflow.com/questions/39360398/exception-the-xpath-expression-evaluated-to-unexpected-type-system-xml-linq-xat

标签

xml

xpath

linq-to-xml