Question

Similar questions have been asked before, but I cannot find the answer to the problem I have.

I want to use linq xml functions to convert my config.xml settings into dictionary, but always got Possible System.NullReferenceException. So, I need to check whether the attribute and its values exist.

What’s the syntax to do that?

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <Services>
    <add key ="key1"   value ="value1"></add>
    <add key ="key2"   value ="value2"></add>
    <add key ="key3"   value ="value3"></add>
 </Services>
</configuration>

my lambda code:

XDocument doc = XDocument.Load(configFilePath);
var d = (from name in doc.Descendants("Services") select name)
         .ToDictionary(n =>  n.Attribute("key")
         .Value, n.Attribute("value")
         .Value);

Answer 1

Use Descendants("add") instead of Descendants("Services")

var dict = XDocument.Load(configFilePath)
        .Descendants("add")
        .ToDictionary(n => n.Attribute("key").Value, n=> n.Attribute("value").Value);

---

var dict = XDocument.Load(configFilePath)
       .Descendants("Services").First()
       .Descendants("add")
       .ToDictionary(n => n.Attribute("key").Value, n=> n.Attribute("value").Value);