Get XML element value using XML to Linq

Question

A snippet of the XML im querying is

<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <metadata created="2014-11-03T18:13:02.769Z" xmlns="http://example.com/ns/mmd-2.0#" xmlns:ext="http://example.com/ns/ext#-2.0"> <customer-list count="112" offset="0"> <customer id="5f6ab597-f57a-40da-be9e-adad48708203" type="Person" ext:score="100"> <name>Bobby Smith</name> <gender>male</gender> <country>US</country> <birth-span> <start>1965-02-18</start> <end>false</end> </birth-span>

The code im writing to get the elements is

 GetCustomer = from c in XDoc.Descendants(ns + "customer") select new Customer { Name = c.Element(ns + "name").ToString(), Gender = Convert.ToString(c.Element(ns + "gender")), BeginDate = c.Elements("birth-span").Any() ? c.Element("start").Value.ToString() : "No data found"

The problem i have is with birth-span, i never seem to get the value if birth-span exists (there are some records which do not contain the birth-span element). For the records that do contain the birth-span element i have added the namespace variable which doesnt work (throws the error that object is not set to an instance)

 BeginDate = c.Elements(ns + "birth-span").Any() ? c.Element(ns + "start").Value.ToString() : "No data found"

Ive added different variations but either i get the value No Data found OR an error (Seems to be object not set to an instance). Can anyone see what im doing wrong?

Ocelot20 · Accepted Answer · 2014-11-03 21:37:44Z

You're treating start as a direct descendant of c (or customer) by doing this:

BeginDate = c.Elements("birth-span").Any() ? c.Element("start").Value.ToString() : "No data found"

When you actually want to do treat start as a direct descendant of the birth-span element like so:

BeginDate = c.Elements("birth-span").Any() ? c.Element("birth-span").Element("start").Value.ToString() : "No data found"

There's room for improvement though. Is there either zero or one birth-span element, or zero or many? As it seems like it's zero or one, you could do this and make it a little clearer:

var customers = from c in doc.Descendants("customer") let birthSpan = c.Element("birth-span") select new { Name = c.Element("name").Value, Gender = c.Element("gender").Value, BeginDate = birthSpan == null ? "No data found" : birthSpan.Element("start").Value };

Also, there's no need to call Convert.ToString or .ToString() on any of these. If you want a string, .Value() will do. If you actually want it typed to something else, directly cast it and let the conversion operators do the work:

var customers = from c in doc.Root.Descendants("customer") let birthSpan = c.Element("birth-span") select new { Name = (string)c.Element("name"), Gender = (string)c.Element("gender"), BeginDate = birthSpan == null ? (DateTime?)null : (DateTime?)birthSpan.Element("start") };

There's a great article about that here.

Thanks - very helpful. Before going into the advanced theories i tried getting the basic way to work first by using this code BeginDate = c.Elements("birth-span").Any() ? c.Element("birth-span").Element("start").Value.ToString() : "No data found" but still this returns "No data found"?
Did you re-add the ns+ as @Thirisangu suggests? I removed them to try to simplify, but they will still be necessary in your code.

Collectives™ on Stack Overflow

Get XML element value using XML to Linq

1 Answer 1

3 Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Related