Newtonsoft JSON, check if property and its value exists

I have an API where I get JSON as an input and I want to check if the specified property and it's value exists in that JSON.

Note: The JSON is not generated from code but is typed by the user so I cannot validate the JSON while serializing.

Consider the following JSON:

{
  "id": 1,
  "someProperties": 
  {
    "property1": "abc",
    "property2": ["zzz", "ccc"]
  }
}

In someProperties, property1 and property2 both can either exists at the same time or anyone of them. So I want to check which all properties are present. And if present, whether that property has the valid value.

I tried the following code:

dynamic request = JsonConvert.DeserializeObject(JSONRequestData);
var X = request["someProperties"]["property1"];

Following are the two scenarios I have to check with their respective responses:

If "property1": "abc" is not present in JSON then I am getting null in X
If I put property1 in JSON without its value which will look something like this "property1": , then I am getting null.

So how do I differentiate between property not being present in JSON and value of property not being present?

Solution

dynamic request = JsonConvert.DeserializeObject(JSONRequestData); always creates a request as JObject, so you can use the methods of JObject. JObject itself implements the IDictionary<string, JToken> interface, which provides the ContainsKey method. So you can simply do

request.someproperties.ContainsKey("property1");

This will return true only if someproperties contains a property named property1, regardless of it's value. Ie, it doesn't matter if request.someproperties.property1 is null or any type, as long as it is contained in the object.