Check if json object is exists

Question

I'd like to check if the json object deserialized using Newtonsoft is empty. I am using this code which feels a little hacky:

try{
dynamic jsonObject = JsonConvert.DeserializeObject(jsonString);
dynamic content = jsonObject.content.important;

 if (((JObject)content).ToString() != "{}"){ // inspecting if "imporant" has value
  // do stuff
  }
}catch(Exception e){
  // handle error
}

Is there a more "stylist" approach to inspecting if object exists?

JObject are dictionaries, you can look at the Count properties, which would be 0 if the object is empty. — Jazzwave06, Nov 25 '19 at 18:40
You can use `JsonExtensions.IsNullOrEmpty()` from [this answer](https://stackoverflow.com/a/24067483) to [Checking for empty/null JToken in a JObject](https://stackoverflow.com/q/24066400). In fact this looks like a duplicate, agree? — dbc, Nov 25 '19 at 23:16

score 3 · Answer 1 · answered Nov 25 '19 at 18:48

You can check count of JTokens available in JObject content. It will return 0, if JObject is empty. Like,

try
{
    dynamic jsonObject = JsonConvert.DeserializeObject(jsonString);
    dynamic content = jsonObject.content.important;

    if (((JObject)content).Count > 0){ // inspecting if "imporant" has value
        // do stuff
      }
}
catch(Exception e)
{
  // handle error
}

score 0 · Answer 2 · answered Nov 25 '19 at 18:38

0

Just check the content of the jsonString string variable before you deserialize it. You're overcomplicating things by deserializing, then serializing, then comparing.

A JSON object always starts and ends with { / }, and if you mean that an "empty" object is an object that has no properties within, then you're checking if the string value is equal to {}.

if (jsonString.Trim() == "{}")
{
   // object is empty
}
else
{
   // do deserialization 
}

The Trim() is put in just in case there is whitespace surrounding the brackets.

Note you'll have 2 edge cases here:

If there is whitespace between the brackets this code will think it's not empty, which is wrong.
This doesn't care if the string is valid JSON or not.

answered Nov 25 '19 at 18:38

gunr2171

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For 1 you can just use string.Replace instead of trim – DetectivePikachu Nov 25 '19 at 19:07
@DetectivePikachu true, problem is that you'll need to replace every whitespace unicode character, and that's such an edge case that I don't want to get into it. – gunr2171 Nov 25 '19 at 19:08
@gunr2171, OP does not want to check that root node is empty or not. He is trying to check JObject `jsonObject.content.important` contains any `JToken` or not. Kindly check OP's code `dynamic content = jsonObject.content.important;` – Prasad Telkikar Nov 25 '19 at 19:32
1

@PrasadTelkikar you're totally correct. Didn't realise that myself until much after I posted this. Uh, I'll leave this post here for a bit longer than probably delete it later. – gunr2171 Nov 25 '19 at 19:34

Check if json object is exists

2 Answers2