Checking for empty or null JToken in a JObject

Question

I have the following...

JArray clients = (JArray)clientsParsed["objects"];  foreach (JObject item in clients.Children()) {     // etc.. SQL params stuff...     command.Parameters["@MyParameter"].Value = JTokenToSql(item["thisParameter"]); } 

JTokenToSql looks like this...

public static object JTokenToSql(JToken obj) {     if (obj.Any())         return (object)obj;     else         return (object)DBNull.Value; } 

I have tried ((JObject)obj).Count also.. But doesn't seem to be working.

Answer 1

To check whether a property exists on a JObject, you can use the square bracket syntax and see whether the result is null or not. If the property exists, a JToken will be always be returned (even if it has the value null in the JSON).

JToken token = jObject["param"]; if (token != null) {     // the "param" property exists } 

If you have a JToken in hand and you want to see if it is non-empty, well, that depends on what type of JToken it is and how you define "empty". I usually use an extension method like this:

public static class JsonExtensions {     public static bool IsNullOrEmpty(this JToken token)     {         return (token == null) ||                (token.Type == JTokenType.Array && !token.HasValues) ||                (token.Type == JTokenType.Object && !token.HasValues) ||                (token.Type == JTokenType.String && token.ToString() == String.Empty) ||                (token.Type == JTokenType.Null);     } } 

Answer 2

You can proceed as follows to check whether a JToken Value is null

JToken token = jObject["key"];  if(token.Type == JTokenType.Null) {     // Do your logic }