title: Json.Net Deserializing "NA" for Numeric Values
body: <p>I am trying to deserialize numeric data using Json.Net where a value might be specified as "NA" if it is missing, e.g.</p>
  
  <pre><code>{
      "readings": [
          { "temperature" : 75 } ,
          { "temperature" : "NA" }
      ]
  }
  </code></pre>
  
  <p>I would like to parse the values into a <i>double?</i> type, e.g.</p>
  
  <pre><code>public class Reading
  {
      public double? Temperature { get; set; }
  }
  </code></pre>
  
  <p>Where (net effect) the first Reading from my example would be "75" and the second would be "null".</p>
  
  <p>I do not have any control over the JSON that is being provided to me.</p>
  
  <p>Is a JsonConverter the only way to get Json.Net to handle this for me, or is there some easier way?  (I can always create a private class variable for the Json deserialized value and then add my own public property that does whatever I want to the private value, but as I have a lot of properties to deal with it would be a lot of extra code.)</p>