C# - Get value of xml element with its attribute

Question

I am trying to get the value of an element using a XML attribute criteria. Essentially I just want one value from the entire document and I've been trying to query it directly. This is my XML file:

<?xml version="1.0" encoding="UTF-8"?>
<list version="1.0">
   <meta>
      <type>resource-list</type>
   </meta>
   <resources start="0" count="1">
      <resource classname="Quote">
         <field name="name">Microsoft Corporation</field> <!-- I want this!!! -->
         <field name="price">49.869999</field>
         <field name="symbol">MSFT</field>
         <field name="ts">1461960000</field>
         <field name="type">equity</field>
         <field name="utctime">2016-04-29T20:00:00+0000</field>
         <field name="volume">48411684</field>
      </resource>
   </resources>
</list>

In particular, I want the field with the "name" attribute in it. This is what I've done to retrieve this:

            XDocument xDoc = XDocument.Parse(httpResponseBody);
            string name = (string)xDoc.Elements("field").First(x => x.Attribute("name").Value == "name");

I get an "element not matching sequence" error. When I try to experiment with this or change anything, I get an object not set to reference error.

I sense that I've made a simple parsing mistake here, but any help would be appreciated (as well as where I've gone wrong and what I can do to prevent this in the future!)

Thank-you!

string name = xDoc.SelectSingleNode("//field[@name='name']").InnerText — Mathias R. Jessen
– Mathias R. Jessen, Commented May 1, 2016 at 9:13
@MathiasR.Jessen using LINQ is preferred, but if you must use XPath you need xDoc.XPathSelectElement(...). There is no SelectSingleNode method on XDocument. — Charles Mager
– Charles Mager, Commented May 1, 2016 at 9:26
Try this instead : var results = xDoc.Descendants("field").Where(x => x.Attribute("name").Value == "name").FirstOrDefault(); — jdweng
– jdweng, Commented May 1, 2016 at 10:18

Charles Mager · Accepted Answer · 2016-05-01 09:18:25Z

2

The Elements query only finds immediate children of the current node. i.e. Elements will only return the root list element.

This either means you need to query like:

doc.Elements("list").Elements("resources").Elements(...

Or you can use Descendants, which will many any descendant of the current node, so:

var name = (string)doc.Descendants("field")
    .First(x => (string)x.Attribute("name") == "name");

answered May 1, 2016 at 9:18

Charles Mager

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1 Comment

ForeverLearning Over a year ago

Thank-you for the explanation, works perfectly now :).

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