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

User · Accepted Answer

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);
    }
}

User · Answer

As of C  7 you could also use this   if  clientsParsed  objects   is JArray clients         foreach  JObject item in clients Children                  if  item  thisParameter   as JToken itemToken                         command Parameters   MyParameter   Value   JTokenToSql itemToken                       The is Operator checks the Type and if its corrects the Value is inside the clients variable

User · Answer

Try something like this to convert JToken to JArray   static public JArray convertToJArray JToken obj           if   obj  Type    JTokenType Null  -- gt  You can check if it s null here      if   obj  Type    JTokenType Array          return  JArray  obj       else         return new JArray       this will return an empty JArray

User · Answer

There is also a type - JTokenType Undefined    This check must be included in  Brian Rogers answer    token Type    JTokenType Undefined

User · Answer

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

[c#] Checking for empty or null JToken in a JObject

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